User Manual
TDS 620A, 640A & 644A
Digitizing Oscilloscopes
070-8715-04
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WARRANTY
Tektronix warrants that the products that it manufactures and sells will be free from defects in materials and
workmanship for a period of three (3) years from the date of shipment. If a product proves defective during this
warranty period, Tektronix, at its option, either will repair the defective product without charge for parts and labor,
or will provide a replacement in exchange for the defective product.
In order to obtain service under this warranty, Customer must notify Tektronix of the defect before the expiration
of the warranty period and make suitable arrangements for the performance of service. Customer shall be
responsible for packaging and shipping the defective product to the service center designated by Tektronix, with
shipping charges prepaid. Tektronix shall pay for the return of the product to Customer if the shipment is to a
location within the country in which the Tektronix service center is located. Customer shall be responsible for
paying all shipping charges, duties, taxes, and any other charges for products returned to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or improper or inadequate
maintenance and care. Tektronix shall not be obligated to furnish service under this warranty a) to repair damage
resulting from attempts by personnel other than Tektronix representatives to install, repair or service the product;
b) to repair damage resulting from improper use or connection to incompatible equipment; c) to repair any
damage or malfunction caused by the use of non-Tektronix supplies; or d) to service a product that has been
modified or integrated with other products when the effect of such modification or integration increases the time
or difficulty of servicing the product.
THIS WARRANTY IS GIVEN BY TEKTRONIX IN LIEU OF ANY OTHER WARRANTIES, EXPRESS
OR IMPLIED. TEKTRONIX AND ITS VENDORS DISCLAIM ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TEKTRONIX’
RESPONSIBILITY TO REPAIR OR REPLACE DEFECTIVE PRODUCTS IS THE SOLE AND
EXCLUSIVE REMEDY PROVIDED TO THE CUSTOMER FOR BREACH OF THIS WARRANTY.
TEKTRONIX AND ITS VENDORS WILL NOT BE LIABLE FOR ANY INDIRECT, SPECIAL,
INCIDENTAL, OR CONSEQUENTIAL DAMAGES IRRESPECTIVE OF WHETHER TEKTRONIX OR
THE VENDOR HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.
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German Postal Information
Certificate of the Manufacturer/Importer
We hereby certify that the TDS 620A, TDS 640A, and TDS 644A Oscilloscopes and all factoryĆinstalled options
complies with the RF Interference Suppression requirements of Postal Regulation Vfg. 243/1991, Amended
per Vfg. 46/1992
The German Postal Service was notified that the equipment is being marketed.
The German Postal Service has the right to reĆtest the series and to verify that it complies.
TEKTRONIX
Bescheinigung des Herstellers/Importeurs
Hiermit wird bescheinigt, daß der/die/das TDS 620A, TDS 640A, and TDS 644A Oscilloscopes und alle
fabrikinstallierten Optionen in Übereinstimmung mit den Bestimmungen der AmtsblattĆVerfügung Vfg.
243/1991 und Zusatzverfügung 46/1992 funkentstört sind.
Der Deutschen Bundespost wurde das Inverkehrbringen dieses Gerätes angezeigt und die Berechtigung zur
Überprüfung der Serie auf Einhalten der Bestimmungen eingeräumt.
TEKTRONIX
NOTICE to the user/operator:
The German Postal Service requires that Systems assembled by the operator/user of this instrument must
also comply with Postal Regulation, Vfg. 243/1991, Par. 2, Sect. 1.
HINWEIS für den Benutzer/Betreiber:
Die vom Betreiber zusammengestellte Anlage, innerhalb derer dieses Gerät eingesetzt wird, muß ebenfalls
den Voraussetzungen nach Par. 2, Ziff. 1 der Vfg. 243/1991, genügen.
NOTICE to the user/operator:
The German Postal Service requires that this equipment, when used in a test setup, may only be operated if
the requirements of Postal Regulation, Vfg. 243/1991, Par. 2, Sect. 1.8.1 are complied with.
HINWEIS für den Benutzer/Betreiber:
Dieses Gerät darf in Meßaufbauten nur betrieben werden, wenn die Voraussetzungen des Par. 2, Ziff. 1. 8.1
der Vfg. 243/1991 eingehalten werden.
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EC Declaration of Conformity
We
Tektronix Holland N.V.
Marktweg 73A
8444 AB Heerenveen
The Netherlands
declare under sole responsibility that the
TDS 620A, 640A, & 644A Digitizing Oscilloscopes
meet the intent of Directive 89/336/EEC for Electromagnetic Compatibility.
Compliance was demonstrated to the following specifications as listed in the
official Journal of the European Communities:
EN 50081-1 Emissions:
EN 55022
EN 55022
Radiated
Conducted
EN 60555-2 Power Harmonics
EN 50082-1 Immunity:
IEC 801-2
Electrostatic Discharge
RF Radiated
Fast Transients
Surge
IEC 801-3
IEC 801-4
IEC 801-5
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Welcome
This is the User Manual for the TDS Family Digitizing Oscilloscopes.
The Getting Started section familiarizes you with the operation of the digitizĆ
ing oscilloscope.
Operating Basics covers basic principles of the operation of the oscilloĆ
scope. These articles help you understand why your instrument works the
way it does.
The Reference section teaches you how to perform specific tasks. See
page 3Ć1 for a complete list of tasks covered in that section.
The Appendices provide an options listing, an accessories listing, and other
useful information.
The following documents are related to the use or service of the digitizing
oscilloscope:
Related Manuals
H
H
H
H
H
The TDS Family Digitizing Oscilloscopes Programmer Manual (Tektronix
part number 070Ć8709ĆXX) describes using a computer to control the
digitizing oscilloscope through the GPIB interface.
The TDS Family Option 05 Video Trigger Instruction Manual (Tektronix
part number 070Ć8748ĆXX) describes use of the video trigger option (for
TDS oscilloscopes equipped with that option only).
The TDS 520A, 524A, 540A, 544A, 620A, 640A & 644A Reference (TektroĆ
nix part number 070Ć8711ĆXX) gives you a quick overview of how to
operate the digitizing oscilloscope.
The TDS 620A, 640A, & 644A Performance Verification (Tektronix part
number 070Ć8717ĆXX) tells how to verify the performance of the digitizing
oscilloscope.
The TDS 620A, 640A, & 644A Service Manual (Tektronix part number
070Ć8718ĆXX) provides information for maintaining and servicing the
digitizing oscilloscope to the module level.
TDS 620A, 640A & 644A User Manual
i
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Welcome
In the Getting Started and Reference sections, you will find various proceĆ
dures which contain steps of instructions for you to perform. To keep those
instructions clear and consistent, this manual uses the following convenĆ
tions:
Conventions
H
H
In procedures, names of front panel controls and menu labels appear in
boldface print.
FrontĆpanel and menu names also appear in the same upper and lower
case as is used on the oscilloscope. Front panel names are all upper
case letters, such as, VERTICAL MENU, and CH 1.
H
H
Instruction steps are numbered. The number is omitted if there is only
one step.
When steps require that you make a sequence of selections using
frontĆpanel controls and menu buttons, an arrow ( ➞ ) marks each
transition between a frontĆpanel button and a menu, or between menus.
Also, whether a name is a main menu or side menu item is clearly
indicated: Press VERTICAL MENU ➞ Coupling (main) ➞ DC (side) ➞
Bandwidth (main) ➞ 100 MHz (side).
Using the convention just described results in instructions that are
graphically intuitive and simplifies procedures. For example, the instrucĆ
tion just given replaces these five steps:
1. Press the front panel button VERTICAL MENU.
2. Press the main menu button Coupling.
3. Press the sideĆmenu button DC.
4. Press the main menu button Bandwidth.
5. Press the side menu button 100 MHz.
H
Sometimes you may have to make a selection from a popup menu:
Press TRIGGER MENU ➞ Type (main) ➞ Edge (popup). In this examĆ
ple, you repeatedly press the main menu button Type until Edge is
highlighted in the popĆup menu.
ii
Welcome
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Table of Contents
Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xi
Getting Started
Product Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setting Up for the Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example 1: Displaying a Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example 2: Multiple Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Example 3: Automated Measurements . . . . . . . . . . . . . . . . . . . . . . . .
Example 4: Saving Setups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1Ć1
1Ć3
1Ć7
1Ć8
1Ć14
1Ć18
1Ć24
Operating Basics
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
At a Glance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scaling and Positioning Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2Ć1
2Ć3
2Ć13
2Ć19
2Ć22
2Ć26
Reference
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Acquisition Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Autoset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Color (TDS 644A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cursor Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Delayed Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Display Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Edge Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fast Fourier Transforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć1
3Ć3
3Ć8
3Ć10
3Ć15
3Ć20
3Ć26
3Ć32
3Ć36
TDS 620A, 640A & 644A User Manual
iii
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Table of Contents
File System (Optional on TDS 620A & TDS 640A) . . . . . . . . . . . . . .
Hardcopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Horizontal Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Limit Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Logic Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Measurement System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Probe Cal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Probe Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Probe Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pulse Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remote Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving and Recalling Setups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saving and Recalling Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selecting Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Signal Path Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Triggering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vertical Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Waveform Differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Waveform Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Waveform Math . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Zoom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć53
3Ć57
3Ć65
3Ć66
3Ć70
3Ć75
3Ć83
3Ć94
3Ć100
3Ć102
3Ć109
3Ć116
3Ć120
3Ć123
3Ć126
3Ć128
3Ć130
3Ć132
3Ć136
3Ć139
3Ć143
3Ć148
3Ć151
Appendices
Appendix A: Options and Accessories . . . . . . . . . . . . . . . . . . . . . . . .
Appendix B: Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix C: Packaging for Shipment . . . . . . . . . . . . . . . . . . . . . . . . .
Appendix D: Factory Initialization Settings . . . . . . . . . . . . . . . . . . . . .
AĆ1
AĆ7
AĆ21
AĆ23
Glossary
Index
iv
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List of Figures
Figure 1Ć1:ăRear Panel Controls Used in Start Up . . . . . . . . . . . . . .
1Ć4
1Ć5
Figure 1Ć2:ăON/STBY Button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć3:ăConnecting a Probe for the Examples . . . . . . . . . . . . .
Figure 1Ć4:ăSETUP Button Location . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć5:ăThe Displayed Setup Menu . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć6:ăTrigger Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć7:ăThe Display After Factory Initialization . . . . . . . . . . . . .
Figure 1Ć8:ăThe VERTICAL and HORIZONTAL Controls . . . . . . . . .
Figure 1Ć9:ăTRIGGER Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć10:ăAUTOSET Button Location . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć11:ăThe Display After Pressing Autoset . . . . . . . . . . . . . . .
Figure 1Ć12:ăDisplay Signals Requiring Probe Compensation . . .
Figure 1Ć13:ăThe Channel Buttons and Lights . . . . . . . . . . . . . . . . .
Figure 1Ć14:ăThe Vertical Main Menu and Coupling Side Menu . .
Figure 1Ć15:ăThe Menus After Changing Channels . . . . . . . . . . . . .
1Ć7
1Ć8
1Ć8
1Ć9
1Ć10
1Ć11
1Ć12
1Ć12
1Ć13
1Ć13
1Ć14
1Ć16
1Ć17
Figure 1Ć16:ăMeasure Main Menu and Select Measurement
Side Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1Ć18
1Ć20
1Ć21
1Ć22
1Ć25
2Ć13
2Ć16
2Ć17
Figure 1Ć17:ăFour Simultaneous Measurement Readouts . . . . . . .
Figure 1Ć18:ăGeneral Purpose Knob Indicators . . . . . . . . . . . . . . . .
Figure 1Ć19:ăSnapshot of Channel 1 . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 1Ć20:ăSave/Recall Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2Ć1:ăTriggered Versus Untriggered Displays . . . . . . . . . . . .
Figure 2Ć2:ăTrigger Holdoff Time Ensures Valid Triggering . . . . . .
Figure 2Ć3:ăSlope and Level Controls Help Define the Trigger . . .
Figure 2Ć4:ăAcquisition: Input Analog Signal, Sample, and
Digitize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2Ć19
2Ć20
2Ć22
2Ć24
2Ć26
Figure 2Ć5:ăRealĆTime Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2Ć6:ăScaling and Positioning . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2Ć7:ăAliasing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 2Ć8:ăGraticule, Cursor and Automated Measurements . . .
TDS 620A, 640A & 644A User Manual
v
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Table of Contents
Figure 2Ć9:ăCursor Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć1:ăHow the Acquisition Modes Work . . . . . . . . . . . . . . . . .
Figure 3Ć2:ăAcquisition Menu and Readout . . . . . . . . . . . . . . . . . . . .
Figure 3Ć3:ăAcquire Menu Ċ Stop After . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć4:ăDisplay Menu Ċ Setting . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć5:ăDisplay Menu Ċ Palette Colors . . . . . . . . . . . . . . . . . . .
Figure 3Ć6:ăDisplay Menu Ċ Map Reference Colors . . . . . . . . . . . .
Figure 3Ć7:ăDisplay Menu Ċ Restore Colors . . . . . . . . . . . . . . . . . . .
Figure 3Ć8:ăCursor Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć9:ăCursor Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć10:ăH Bars Cursor Menu and Readouts . . . . . . . . . . . . . . .
Figure 3Ć11:ăPaired Cursor Menu and Readouts . . . . . . . . . . . . . . .
Figure 3Ć12:ăDelayed Runs After Main . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć13:ăDelayed Triggerable . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć14:ăHow the Delayed Triggers Work . . . . . . . . . . . . . . . . . .
Figure 3Ć15:ăDelayed Trigger Menu . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć16:ăDisplay Menu Ċ Style . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć17:ăTrigger Point and Level Indicators . . . . . . . . . . . . . . . .
Figure 3Ć18:ăEdge Trigger Readouts . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć19:ăMain Trigger Menu Ċ Edge Type . . . . . . . . . . . . . . . . .
Figure 3Ć20:ăSystem Response to an Impulse . . . . . . . . . . . . . . . . .
Figure 3Ć21:ăDefine FFT Waveform Menu . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć22:ăFFT Math Waveform in Math1 . . . . . . . . . . . . . . . . . . . .
Figure 3Ć23:ăCursor Measurement of an FFT Waveform . . . . . . . .
Figure 3Ć24:ăWaveform Record vs. FFT Time Domain Record . . .
2Ć27
3Ć4
3Ć5
3Ć6
3Ć10
3Ć12
3Ć13
3Ć14
3Ć15
3Ć16
3Ć17
3Ć18
3Ć20
3Ć20
3Ć22
3Ć24
3Ć26
3Ć28
3Ć32
3Ć33
3Ć37
3Ć38
3Ć39
3Ć41
3Ć43
Figure 3Ć25:ăFFT Time Domain Record vs. FFT Frequency Domain
Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć43
3Ć47
3Ć50
3Ć52
3Ć53
3Ć55
3Ć58
Figure 3Ć26:ăHow Aliased Frequencies Appear in an FFT . . . . . . .
Figure 3Ć27:ăWindowing the FFT Time Domain Record . . . . . . . . .
Figure 3Ć28:ăFFT Windows and Bandpass Characteristics . . . . . .
Figure 3Ć29:ăFile Utilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć30:ăFile System Ċ Labelling Menu . . . . . . . . . . . . . . . . . . .
Figure 3Ć31:ăUtility Menu Ċ System I/O . . . . . . . . . . . . . . . . . . . . . . .
vi
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Figure 3Ć32:ăHardcopy Formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć33:ăDate and Time Display . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć59
3Ć61
Figure 3Ć34:ăConnecting the Digitizing Oscilloscope Directly to the
Hardcopy Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć62
Figure 3Ć35:ăConnecting the Digitizing Oscilloscope and Hardcopy
Device Via a PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć63
3Ć65
Figure 3Ć36:ăInitial Help Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć37:ăHorizontal Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć38:ăRecord View and Time Base Readouts . . . . . . . . . . . .
Figure 3Ć39:ăComparing a Waveform to a Limit Template . . . . . . .
Figure 3Ć40:ăAcquire Menu Ċ Create Limit Test Template . . . . . .
Figure 3Ć41:ăLogic Trigger Readouts . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć42:ăLogic Trigger Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć43:ăLogic Trigger Menu Ċ Time Qualified TRUE . . . . . . .
Figure 3Ć44:ăMeasurement Readouts . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć45:ăMeasure Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć46:ăMeasure Menu Ċ Gating . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć47:ăMeasure Menu Ċ Reference Levels . . . . . . . . . . . . . .
Figure 3Ć48:ăMeasure Delay Menu Ċ Delay To . . . . . . . . . . . . . . . . .
Figure 3Ć49:ăSnapshot Menu and Readout . . . . . . . . . . . . . . . . . . . .
Figure 3Ć50:ăProbe Cal Menu and Gain Compensation Display .
Figure 3Ć51:ăReĆuse Probe Calibration Data Menu . . . . . . . . . . . . .
Figure 3Ć52:ăHow Probe Compensation Affects Signals . . . . . . . .
Figure 3Ć53:ăP6139A Probe Adjustment . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć54:ăThe P6009 and P6015A High Voltage Probes . . . . . .
Figure 3Ć55:ăA6303 Current Probe Used in the AM 503SOpt. 03
Figure 3Ć56:ăPulse Trigger Readouts . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć57:ăMain Trigger Menu Ċ Glitch Class . . . . . . . . . . . . . . .
Figure 3Ć58:ăMain Trigger MenuĊRunt Class . . . . . . . . . . . . . . . . . .
Figure 3Ć59:ăTypical GPIB Network Configuration . . . . . . . . . . . . . .
Figure 3Ć60:ăStacking GPIB Connectors . . . . . . . . . . . . . . . . . . . . . .
3Ć66
3Ć67
3Ć70
3Ć71
3Ć76
3Ć78
3Ć81
3Ć86
3Ć87
3Ć88
3Ć90
3Ć91
3Ć92
3Ć96
3Ć98
3Ć100
3Ć101
3Ć103
3Ć105
3Ć109
3Ć111
3Ć114
3Ć117
3Ć117
Figure 3Ć61:ăConnecting the Digitizing Oscilloscope to a
Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć118
3Ć119
Figure 3Ć62:ăUtility Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TDS 620A, 640A & 644A User Manual
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Table of Contents
Figure 3Ć63:ăSave/Recall Setup Menu . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć64:ăSave Waveform Menu . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć65:ăMore Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć66:ăThe Channel Readout . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć67:ăWaveform Selection Priority . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć68:ăPerforming a Signal Path Compensation . . . . . . . . . .
Figure 3Ć69:ăStatus Menu Ċ System . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć70:ăBanner Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć71:ăTRIGGER Controls and Status Lights . . . . . . . . . . . . .
Figure 3Ć72:ăExample Trigger Readouts . . . . . . . . . . . . . . . . . . . . . . .
3Ć120
3Ć124
3Ć125
3Ć126
3Ć127
3Ć129
3Ć130
3Ć131
3Ć132
3Ć134
Figure 3Ć73:ăRecord View, Trigger Position, and Trigger Level Bar
Readouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć135
3Ć137
3Ć140
Figure 3Ć74:ăVertical Readouts and Channel Menu . . . . . . . . . . . . .
Figure 3Ć75:ăDerivative Math Waveform . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć76:ăPeakĆPeak Amplitude Measurement of a Derivative
Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć141
3Ć144
Figure 3Ć77:ăIntegral Math Waveform . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć78:ăH Bars Cursors Measure an Integral Math
Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3Ć145
3Ć148
3Ć150
3Ć152
AĆ10
Figure 3Ć79:ăMore Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure 3Ć80:ăDual Waveform Math Main and Side Menus . . . . . . .
Figure 3Ć81:ăZoom Mode with Horizontal Lock Set to None . . . . .
Figure AĆ1:ăMCross Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure AĆ2:ăFall Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figure AĆ3:ăRise Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AĆ13
AĆ17
Figure AĆ4:ăChoosing Minima or Maxima to Use for Envelope
Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AĆ19
viii
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List of Tables
Table 1Ć1:ăFuse and Fuse Cap Part Numbers . . . . . . . . . . . . . . . . . .
1Ć4
3Ć9
TableĂ3Ć1:ăAutoset Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć2:ăXY Format Pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć3:ăLogic Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć4:ăMeasurement Definitions . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć5:ăProbe Cal Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć6:ăTDS 600A Compatible Probes . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć7:ăProbes by Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć8:ăPulse Trigger Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂ3Ć9:ăZoom Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂAĆ1:ăInternational Power Cords . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂAĆ2:ăStandard Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂAĆ3:ăOptional Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂAĆ4:ăAccessory Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TableĂAĆ5:ăFactory Initialization Defaults . . . . . . . . . . . . . . . . . . . . . .
3Ć30
3Ć77
3Ć83
3Ć98
3Ć107
3Ć108
3Ć110
3Ć153
AĆ1
AĆ3
AĆ4
AĆ5
AĆ23
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Table of Contents
x
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Safety
Please take a moment to review these safety precautions. They are provided
for your protection and to prevent damage to the digitizing oscilloscope.
This safety information applies to all operators and service personnel.
These two terms appear inmanuals:
Symbols and Terms
H
H
statements identify conditions or practices that could result in
damage to the equipment or other property.
statements identify conditions or practices that could result in
personal injury or loss of life.
These two terms appear onequipment:
H
CAUTION indicates a personal injury hazard not immediately accessible
as one reads the marking or a hazard to property including the equipĆ
ment itself.
H
DANGER indicates a personal injury hazard immediately accessible as
one reads the marking.
This symbol appears inmanuals:
StaticĆSensitive Devices
These symbols appear onequipment:
DANGER
High Voltage
Protective
ground (earth)
terminal
ATTENTION
Refer to
manual
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Safety
Observe all of these precautions to ensure your personal safety and to
prevent damage to either the digitizing oscilloscope or equipment conĆ
nected toit.
Specific Precautions
Power Source
The digitizing oscilloscope is intended to operate from a power source that
will not apply more than 250 V
between the supply conductors or beĆ
RMS
tween either supply conductor and ground. A protective ground connection,
through the grounding conductor in the power cord, is essential for safe
system operation.
Grounding the Digitizing Oscilloscope
The digitizing oscilloscope is grounded through the power cord. To avoid
electric shock, plug the power cord into a properly wired receptacle where
earth ground has been verified by a qualified service person. Do this before
making connections to the input or output terminals of the digitizing oscilloĆ
scope.
Without the protective ground connection, all parts of the digitizing oscilloĆ
scope are potential shock hazards. This includes knobs and controls that
may appear tobe insulators.
Use the Proper Power Cord
Use only the power cord and connector specified for your product. Use only
a power cord that is in good condition.
Use the Proper Fuse
To avoid fire hazard, use only the fuse specified in the parts list for your
product, matched by type, voltage rating, and current rating.
Do Not Remove Covers or Panels
To avoid personal injury, do not operate the digitizing oscilloscope without
the panels or covers.
Electric Overload
Never apply a voltage to a connector on the digitizing oscilloscope that is
outside the voltage range specified for that connector.
Do Not Operate in Explosive Atmospheres
The digitizing oscilloscope provides no explosion protection from static
discharges or arcing components. Do not operate the digitizing oscilloscope
in an atmosphere of explosive gases.
xii
Safety
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Getting Started
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Product Description
Tektronix TDS 600A Digitizing Oscilloscopes are superb tools for acquiring,
displaying, and measuring waveforms. Their performance addresses the
needs of both benchtop lab and portable applications with the following
features:
H
H
H
500 MHz maximum analog bandwidth.
2 Gigasamples/second maximum digitizing rate.
Four channels for acquisition Ċ the TDS 640A & 644A let you use and
display all four channels simultaneously; the TDS 620A lets you use and
display any two channels simultaneously. All channels can acquire at the
maximum digitizing rate.
H
Waveform Math Ċ Invert a single waveform and add, subtract, multiply,
and divide two waveforms. On instruments with Advanced DSP Math
(standard on the TDS 644A), integrate or differentiate a single waveform
or perform an FFT (fast fourier transform) on a waveform to display its
magnitude or phase versus its frequency.
H
H
H
EightĆbit digitizers.
Up to 2,000Ćsample record length per channel.
Full GPIB software programmability. Hardcopy output using RSĆ232 or
Centronics ports (Optional on TDS 620A & 640A) and the GPIB.
H
H
Complete measurement and documentation capability.
Intuitive graphic icon operation blended with the
familiarity of traditional horizontal and
vertical knobs.
H
OnĆline help at the touch of a button.
TDS 620A, 640A & 644A User Manual
1Ć1
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Product Description
1Ć2
Getting Started
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Start Up
Before you use the digitizing oscilloscope, ensure that it is properly installed
and powered on.
To ensure maximum accuracy for your most critical measurements, you
should know about signal path compensation and the proper use of the
P6139A probe shipped with your oscilloscope as a standard accessory.
Before You Begin
Signal Path Compensation
Be sure you compensate your oscilloscope for the surrounding temperature.
This action, called Signal Path Compensation (SPC), ensures maximum
possible accuracy for your most critical measurements. See Signal Path
Compensation on page 3Ć128 for a description of and operating information
on this feature.
P6205 Active Probe
Be sure you use the appropriate probe. Do not use the optional P6205
Active Probe to measure signals above ±10 volts since errors in signal
measurement will result. Instead, use the standard accessory P6139A
Passive Probe or one of the passive probes listed in Appendix A under
Accessory Probes. The P6139A probe is for measurements up to
±500 volts.
CAUTION
Using the P6205 Active Probe to measure signals greater than
±40 volts may damage the probe.
To properly install and power on the digitizing oscilloscope, do the following:
Operation
Installation
1. Be sure you have the appropriate operating environment. Specifications
for temperature, relative humidity, altitude, vibrations, and emissions are
included in the TDS 620A, 640A, & 644A Performance Verification manuĆ
al (Tektronix part number 070Ć8717ĆXX).
TDS 620A, 640A & 644A User Manual
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Start Up
2. Leave space for cooling. Do this by verifying that the air intake and
exhaust holes on the sides of the cabinet (where the fan operates) are
free of any airflow obstructions. Leave at least 5.1 cm (2 inches) free on
each side.
WARNING
To avoid electrical shock, be sure that the power cord is disconĆ
nected before checking the fuse.
3. Check the fuse to be sure it is the proper type and rating (see FigĆ
ure 1Ć1). You can use either of two fuses. Each fuse requires its own cap
(see Table 1Ć1). The digitizing oscilloscope is shipped with the UL apĆ
proved fuse installed.
4. Check that you have the proper electrical connections. The digitizing
oscilloscope requires 90 to 250 VAC
63 Hz, and may require up to 300ĂW.
, continuous range, 47 Hz to
RMS
5. Connect the proper power cord from the rearĆpanel power connector
(see Figure 1Ć1) to the power system.
Power Connector
Principal Power Switch
Fuse
Figure 1Ć1:ăRear Panel Controls Used in Start Up
Table 1Ć1:ăFuse and Fuse Cap Part Numbers
Fuse
Fuse Part
Number
Fuse Cap Part
Number
.25 inch × 1.25 inch (UL 198.6, 3AG):
6 A FAST, 250 V.
159-0013-00
200-2264-00
5 mm ×20 mm (IEC 127): 5 A (T),
250 V.
159-0210-00
200-2265-00
1Ć4
Getting Started
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Start Up
Front Cover Removal
Remove the front cover by grasping its left and right edges and snapping it
off of the front subpanel. (When reinstalling, align and snap back on.)
Power On
1. Check that the rearĆpanel principal power switch is on (see Figure 1Ć1).
The principal power switch controls all AC power to the instrument.
2. If the oscilloscope is not powered on(the screenis blank), push the
frontĆpanel ON/STBY buttonto toggle it on(see Figure 1Ć2).
The ON/STBY button controls power to most of the instrument circuits.
Power continues to go to certainparts evenwhenthis switch is set to
STBY.
Once the digitizing oscilloscope is installed, it is typical to leave the
principal power switch on and use the ON/STBY buttonas the power
switch.
ON/STBY Button
Figure 1Ć2:ăON/STBY Button
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Start Up
Self Test
Check the self test results. The digitizing oscilloscope automatically perĆ
forms powerĆup tests each time it is turned on. It will come up with a display
screen that states whether or not it passed self test. (If the self test passed,
the status display screen will be removed after a few seconds.)
If the self test fails, call your local TektronixService Center. Depending on
the type of failure, you may still be able to use the oscilloscope before it is
serviced.
Power Off
Toggle the ON/STBY switch to turn off the oscilloscope.
1Ć6
Getting Started
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Setting Up for the Examples
All the examples use the same setup. Once you perform this setup, you do
not have to change the signal connections for any of the other examples.
Remove all probes and signal inputs from the input BNC connectors along
the lower right of the front panel. Then, using one of the probes supplied
with the digitizing oscilloscope, connect from the CH 1 connector to the
PROBE COMPENSATION connectors (see Figure 1Ć3).
Figure 1Ć3:ăConnecting a Probe for the Examples
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Example 1: Displaying a Waveform
In this first example you learn about resetting the digitizing oscilloscope,
displaying and adjusting a waveform, and using the autoset function.
All examples in the tutorial begin by resetting the digitizing oscilloscope to a
known factory default state. Reset the oscilloscope when you begin a new
task and need tostart fresh" with known default settings.
Resetting the
Digitizing
Oscilloscope
1. Press the save/recall SETUP button to display the Setup menu (FigĆ
ure 1Ć4).
SETUP Button
Figure 1Ć4:ăSETUP Button Location
The digitizing oscilloscope displays main menus along the bottom of the
screen. Figure 1Ć5 shows the Setup main menu.
OK Confirm Factory Init
Menu Item and Button
Recall Factory Setup
Menu Item and Button
Figure 1Ć5:ăThe Displayed Setup Menu
1Ć8
Getting Started
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Example1: Displaying a Waveform
2. Press the button directly below the Recall Factory Setup menu item.
The display shows side menus along the right side of the screen. The
buttons to select these side menu items are to the right of the side
menu.
Because an accidental instrument reset could destroy a setupthat took
a long time to create, the digitizing oscilloscope asks you to verify the
Recall Factory Setup selection (see Figure 1Ć5).
3. Press the button to the right of the OK Confirm Factory Init side menu
item.
NOTE
This manual uses the following notation to represent the sequence
of selections you made in steps 1, 2 and 3: Press save/recall
SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory
Init (side).
Note that a clock icon appears on screen. The oscilloscope displays this
icon when performing operations that take longer than several seconds.
4. Press SET LEVEL TO 50% (see Figure 1Ć6) to be sure the oscilloscope
triggers on the input signal.
SET LEVEL TO 50% Button
Figure1Ć6:ăTrigger Controls
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Example 1: Displaying a Waveform
Figure 1Ć7 shows the display that results from the instrument reset. There
are several important points to observe:
Display Elements
H
H
H
The trigger level bar shows that the waveform is triggered at a level near
50% ofits amplitude (from step 4).
The trigger position indicator shows that the trigger position ofthe
waveform is located at the horizontal center of the graticule.
The channel reference indicator shows the vertical position ofchannel 1
with no input signal. This indicator points to the ground level for the
channel when its vertical offset is set to 0 V in the vertical menu; when
vertical offset is not set to 0 V, it points to the vertical offset level.
H
The trigger readout shows that the digitizing oscilloscope is triggering on
channel 1 (Ch1) on a rising edge, and that the trigger level is about
200-300 mV.
H
H
The time base readout shows that the main time base is set to a horizonĆ
tal scale of500Ă ms/div.
The channel readout indicates that channel 1 (Ch1) is displayed with DC
coupling. (In AC coupling, ~ appears after the volts/div readout.) The
digitizing oscilloscope always displays channel 1 at reset.
Trigger Level Bar
Trigger Position Indicator
Channel Reference Indicator
Trigger Readout
Time Base Readout
Channel Readout
Figure 1Ć7:ăThe Display After Factory Initialization
Right now, the channel, time base, and trigger readouts appear in the gratiĆ
cule area because a menu is displayed. You can press the CLEAR MENU
button at any time to remove any menus and to move the readouts below
the graticule.
1Ć10
Getting Started
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Example1: Displaying a Waveform
The display shows the probe compensation signal. It is a 1ĂkHz square wave
of approximately 0.5ĂV amplitude. You can adjust the size and placement of
the waveform using the frontĆpanelknobs.
Adjusting the
Waveform Display
Figure 1Ć8 shows the main VERTICAL and HORIZONTAL sections of the
front panel. Each has SCALE and POSITION knobs.
1. Turn the vertical SCALE knob clockwise. Observe the change in the
displayed waveform and the channel readout at the bottom of the disĆ
play.
Figure1Ć8:ăTheVERTICAL and HORIZONTAL Controls
2. Turn the vertical POSITION knob first one direction, then the other.
Observe the change in the displayed waveform. Then return the waveĆ
form to the center of the graticule.
3. Turn the horizontal SCALE knob one click clockwise. Observe the time
base readout at the bottom of the display. The time base should be set
to 250Ăms/div now, and you should see two complete waveform cycles
on the display.
When you first connect a signalto a channeland dispal y it, the signaldisĆ
played may not be scaled and triggered correctly. Use the autoset function
and you should quickly get a meaningful display.
Using Autoset
When you reset the digitizing oscilloscope, you see a clear, stable display of
the probe compensation waveform. That is because the probe compensaĆ
tion signal happens to display well at the default settings of the digitizing
oscilloscope.
TDS 620A, 640A & 644A User Manual
1Ć11
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Example 1: Displaying a Waveform
1. To create an unstable display, slowly turn the trigger MAIN LEVEL knob
(see Figure 1Ć9) first one direction, then the other. Observe what hapĆ
pens when you move the trigger level above the highest part of the
displayed waveform. Leave the trigger level in that untriggered state.
2. Press AUTOSET (see Figure 1Ć10) and observe the stable waveform
display.
MAIN LEVEL Knob
Figure 1Ć9:ăTRIGGER Controls
AUTOSET Button
Figure 1Ć10:ăAUTOSET Button Location
Figure 1Ć11 shows the display after pressing AUTOSET. If necessary, you
can adjust the waveform now by using the knobs discussed earlier in this
example.
1Ć12
Getting Started
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Example 1: Displaying a Waveform
Figure 1Ć11:ăThe Display After Pressing Autoset
NOTE
If you are using a passive probe, such as the standard P6139A
probe, the corners on your displayed signal may look rounded or
pointed (see Figure 1Ć12). If so, then you may need to compensate
your probe. The documentation included with such probes explains
how to compensate your probe.
Figure 1Ć12:ăDisplay Signals Requiring Probe Compensation
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Example 2: Multiple Waveforms
In this example you learn how to display and control more than one waveĆ
form at a time.
The VERTICAL section of the front panelcontains the channelseel ction
buttons. These are CH 1, CH 2, CH 3, CH 4, and MORE (Figure 1Ć13); on
the TDS 620A, they areCH 1, CH 2, AUX 1, AUX 2, and MORE.
Adding a Waveform
Figure 1Ć13:ăThe Channel Buttons and Lights
Each of the channel( CH) buttons has a light above its label. Right now, the
CH 1 light is on. That light indicates that the vertical controls are set to
adjust channel1.
The following steps add a waveform to the display.
1. If you are not continuing from the previous example, follow the instrucĆ
tions on page 1Ć7 under the heading Setting Up for the Examples.
2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory
Init (side).
1Ć14
Getting Started
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Example 2: Multiple Waveforms
3. Press AUTOSET.
4. Press CH 2.
The display shows a second waveform, which represents the signal on
channel 2. Since there is nothingconnected to the CH 2 input connecĆ
tor, this waveform is a flat line.
There are several other important things to observe:
H
H
H
The channel readout on the display now shows the settings for both
Ch1 and Ch2.
There are two channel indicators at the left edge of the graticule.
Right now, they overlap.
The light next to the CH 2 button is now on, and the CH 1 light is off.
Because the knobs control only one channel at a time, the vertical
controls are now set to adjust channel 2.
H
The trigger readout still indicates that the trigger is detecting trigger
events on Ch1. The trigger source is not changed simply by adding
a channel. (You can change the trigger source by using the TRIGĆ
GER MENU button to display the trigger menu.)
5. Turn the vertical POSITION knob clockwise to move the channelĂ2
waveform up on the graticule. You will notice that the channel reference
indicator for channelĂ2 moves with the waveform.
6. Press VERTICAL MENU ➞ Coupling (main).
The VERTICAL MENU button displays a menu that gives you control
over many vertical channel parameters (Figure 1Ć14). Although there can
be more than one channel displayed, the vertical menu and buttons only
adjust the selected channel.
Each menu item in the Vertical menu displays a side menu. Right now,
the Coupling item in the main menu is highlighted, which means that
the side menu shows the couplingchoices. At the top of the side menu,
the menu title shows the channel affected by the menu choices. That
always matches the lighted channel button.
7. Press W (side) to toggle the selection to 50 W. That changes the input
couplingof channel 2 from 1 MW to 50 W. The channel readout for
channel 2 (near the bottom of the graticule) now shows an W indicator.
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Example 2: Multiple Waveforms
Ch2 Reference Indicator
Side Menu Title
Figure 1Ć14:ăThe Vertical Main Menu and Coupling Side Menu
Pressing a channel (CH) button sets the vertical controls to that channel. It
also adds the channel to the display if that waveform is not already disĆ
played.
Changing Controls
to Another Channel
1. Press CH 1.
Observe that now the side menu title shows Ch1 (Figure 1Ć15), and that
the light above CH 1 is lighted. The highlighted menu item in the side
menu has changed from the 50ĂW channel 2 setting to the 1ĂMW impedĆ
ance setting of channel 1.
2. Press CH 2 ➞ W (side) to toggle the selection to 1ĂMW. That returns the
coupling impedance of channel 2 to its initial state.
1Ć16
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Example 2: Multiple Waveforms
Side Menu Title
Figure 1Ć15:ăThe Menus After Changing Channels
Pressing the WAVEFORM OFF button removes the waveform for the curĆ
rently selected channel. If the waveform youwant to remove is not already
selected, select that channel using the channel (CH) button.
Removing a
Waveform
1. Press WAVEFORM OFF (under the vertical SCALE knob).
Since the CH 2 light was on when youpressed the WAVEFORM OFF
button, the channel 2 waveform was removed.
The channel (CH) lights now indicate channel 1. Channel 1 has become
the selected channel. When youremove the last waveform, all the CH
lights are turned off.
2. Press WAVEFORM OFF again to remove the channel 1 waveform.
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Example 3: Automated Measurements
In this example you learn how to use the automated measurement system to
get numeric readouts of important waveform characteristics.
To use the automated measurement system, you must have a stable display
of your signal. Also, the waveform must have all the segments necessary for
the measurement you want. For example, a rise time measurement requires
at least one rising edge, and a frequency measurement needs at least one
complete cycle.
Displaying
Automated
Measurements
1. If you are not continuing from the previous example, follow the instrucĆ
tions on page 1Ć7 under the heading Setting Up for the Examples.
2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory
Init (side).
3. Press AUTOSET.
4. Press MEASURE to display the Measure main menu (see Figure 1Ć16).
Figure 1Ć16:ăMeasure Main Menu and Select Measurement Side Menu
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Example 3: Automated Measurements
5. If it is not already selected, press Select Measrmnt (main). The readout
for that menu item indicates which channel the measurement will be
taken from. All automated measurements are made on the selected
channel.
The Select Measurement side menu lists some of the measurements
that can be taken on waveforms. There are many different measureĆ
ments available; up to four can be taken and displayed at any one time.
Pressing the button next to the -more- menu item brings up the other
measurement selections.
6. Press Frequency (side). If the Frequency menu item is not visible, press
-more- (side) repeatedly until the Frequency itemappears. Then
press Frequency (side).
Observe that the frequency measurement appears within the right side
of the graticule area. The measurement readout includes the notation
Ch1, meaning that that measurement is taken on the channel 1 waveĆ
form. (To take a measurement on another channel, select that channel,
and then select the measurement.)
7. Press Positive Width (side) ➞ -more- (side) ➞ Rise Time (side) ➞
Positive Duty Cycle (side).
All four measurements are displayed. Right now, they cover a part of the
graticule area, including the displayed waveforms.
8. To move the measurement readouts outside the graticule area, press
CLEAR MENU (see Figure 1Ć17).
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Example 3: Automated Measurements
Press here to
remove menus
from screen.
Figure 1Ć17:ăFour Simultaneous Measurement Readouts
The Measure menu lets you remove measurements you no longer want
displayed. You can remove any one measurement, or you can remove them
all with a single menu item.
Removing
Measurement
Readouts
Press MEASURE ➞ Remove Measrmnt (main) ➞ MeasurementĂ1, MeaĆ
surementĂ2, and MeasurementĂ4 (side) to remove those measurements.
Leave the rise time measurement displayed.
By default, the measurement system will use the 10% and 90% levels of the
waveform for taking the rise time measurement. You can change these
values to other percentages or change them to absolute voltage levels.
Changing the
Measurement
Reference Levels
Toexamine the current values, press Reference Levels (main) ➞ High Ref
(side).
The GeneralPurpose Knob
The general purpose knob, the large knob, is now set to adjust the high
reference level (Figure 1Ć18).
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Example 3: AutomatedMeasurements
General Purpose Knob
Setting and Readout
General Purpose
Knob Icon
Highlighted Menu Item with
Boxed Readout Value
Figure 1Ć18:ăGeneral Purpose Knob Indicators
There are several important things to observe on the screen:
H
The knob icon appears at the top of the screen. The knob icon indicates
that the general purpose knob has just been set to adjust a parameter.
H
H
The upper right corner of the screen shows the readout High Ref: 90%.
The High Ref side menu item is highlighted, and a box appears around
the 90% readout in the High Ref menu item. The box indicates that the
general purpose knob is currently set to adjust that parameter.
Turn the general purpose knob left and right, and then use it to adjust the
high level to 80%. That sets the high measurement reference to 80%.
Hint: To make large changes quickly with the general purpose knob, press
the SHIFT button before turning the knob. When the light above the SHIFT
button is on and the display says Coarse Knobs in the upperĆright corner,
the general purpose knob speeds up significantly.
The Numeric Keypad
Any time the general purpose knob is set to adjust a numeric parameter,
you can enterthe value as a numberusing the keypad instead of using the
knob. Always end the entry of a number by pressing the ENTER (
).
The numeric keypad also provides multipliers for engineering exponents,
such as m formilli, M formega, and m formicro. To enterthese multiplier
values, press the SHIFT button, then press the multiplier.
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Example 3: Automated Measurements
1. Press Low Ref (side).
2. On the numeric keypad, press the 2, the 0, and the ENTER (
) butĆ
tons, which sets the low measurement reference to 20%. Observe that
the riseĆtime value has changed.
3. Press Remove Measrmnt (main) ➞ All Measurements (side). That
returns the display toits original state.
You have seen how to display up to four individual automated measureĆ
ments on screen. You can also pop up a display of almost all of the autoĆ
mated measurements available in the Select Measrmnts side menus. This
snapshot of measurements is taken on the waveform currently selected
using the channel selection buttons.
Displaying a
Snapshot of
Automated
Measurements
As when displaying individual measurements, you must have a stable disĆ
play of your signal, and that signal must have all the segments necessary for
the measurement you want.
1. Press Snapshot (main) to pop up a snapshot of all available single
waveform measurements. (See Figure 1Ć19).
Figure 1Ć19:ăSnapshot of Channel 1
The snapshot display includes the notation Ch 1, meaning that the
measurements displayed are taken on the channel 1 waveform. You
take a snapshot of a waveform in another channel by first selecting that
channel using the channel selection buttons.
1Ć22
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Example 3: Automated Measurements
The snapshot measurements do not continuously update. Snapshot
executes a oneĆtime capture of all measurements and does not update
those measurements unless it is performed again.
2. Press Again (side) to do another snapshot and update the snapshot
measurements.
3. Press Remove Measrmnt (main) to remove the snapshot display. (You
can also press CLEAR MENU, but a newsnapshot will be executed the
next time you display the Measure menu.)
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Example 4: Saving Setups
This example shows you how to save all the settings of the digitizing oscilloĆ
scope and how to recall the setup later to quickly reĆestablish the previously
saved state. The oscilloscope provides several storage locations where you
can save the setups. With the file system (optional on the TDS 620A &
TDS 640A), you can also save setups to a floppy disk.
Besides being able to save several complete setups, the digitizing oscilloĆ
scope remembers all the parameter settings when you power it off. That
feature lets you power on and continue where you left off without having to
reconstruct the state of the digitizing oscilloscope.
First, you need to create an instrument setup you want to save. The next
several steps establisha twoĆwaveform display witha measurement on one
waveform. The setup created is complex enough that you might prefer not
to go through all these steps each time you want that display.
Saving a Setup
1. If you are not continuing from the previous example, follow the instrucĆ
tions on page 1Ć7 under the heading Setting Up for the Examples.
2. Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory
Init (side).
3. Press ➞ AUTOSET.
4. Press MEASURE ➞ Select Measrmnt (main) ➞ Frequency (side).
(Press the -more- side menu item if the Frequency selection does not
appear in the side menu.)
5. Press CH 2 ➞ CLEAR MENU.
6. Press SETUP ➞ Save Current Setup (main) to display the Setup main
menu (see Figure 1Ć20).
Note that the setup locations shown in the side menu are labeled
either user or factory. If you save your current setup in a location
labeled user, you will overwrite the user setup previously stored
there. If you work in a laboratory environment where several people
share the digitizing oscilloscope, check with the other users before
you overwrite their setup. Setup locations labeled factory have the
factory setup stored as a default and can be used to store current
setups without disturbing previously stored setups.
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Example4: Saving Setups
Figure 1Ć20:ăSave/Recall Setup Menu
7. Press one of the To Setup side menu buttons to store the current instruĆ
ment settings into that setup location. Remember which setup location
you selected for use later.
There are more setup locations than can be listed at one time in the side
menu. The -more- side menu item gives you access to all the setup
locations.
Once you have saved a particular setup, you can change the settings as
you wish, knowing that you can come back to that setup at any time.
8. Press MEASURE ➞ PositiveWidth (side) to add that measurement to
the display.
To recall the setup, Press SETUP ➞ Recall Saved Setup (main) ➞ Recall
Recalling a Setup
Setup (side) for the setup location you used in the last exercise. The positive
width measurement is now removed from the display because you selected
it after you saved the setup.
This completes the tutorial. You can restore the default settings by pressing
SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory Init (side).
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Example 4: Saving Setups
1Ć26
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Operating Basics
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Overview
This section describes the basic concepts of operating the digitizing oscilloĆ
scope. Understanding the basic concepts of your digitizing oscilloscope will
help you use it much more effectively.
The first part, At a Glance, quickly shows you how the oscilloscope is orgaĆ
nized and gives some very general operating instructions. It also contains an
overview of all the main menus. This part includes:
H
H
H
H
H
Front Panel Map
Rear Panel Map
Display Map
Basic Menu Operation
Menu Map
The second part explains the following concepts:
H
The triggering system, which establishes conditions for acquiring
signals. Properly set, triggers can convert displays from unstable
jumbles or blank screens into meaningful waveforms. See Triggering on
page 2Ć13.
H
H
The acquisition system, which converts analog data into digital form.
See Acquisition on page 2Ć19.
The waveform scaling and positioning system, which changes the
dimensions of the waveform display. Scaling waveforms involves inĆ
creasing or decreasing their displayed size. Positioning means moving
them up, down, right, or left on the display. See Scaling and Positioning
Waveforms on page 2Ć22.
H
The measurement system, which provides numeric information on the
displayed waveforms. You can use graticule, cursor, and automated
measurements. See Measurements on page 2Ć26.
At the end of each topic, For More Information will point you to sources
where more information can be found.
To explore these topics in more depth and to read about topics not covered
in this section, see Reference. Page 3Ć1 lists the topics covered.
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Overview
2Ć2
Operating Basics
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At a Glance
The At a Glance section contains illustrations of the display, the front and
rear panels, and the menu system. These will help you understand and
operate the digitizing oscilloscope. This section also contains a visual guide
to using the menu system.
Front Panel Map Ċ
Left Side
File System,
page 3Ć53
(Optional on
TDS 620A &
TDS 640A)
Side Menu Buttons,
page 2Ć7
ON/STBY Switch,
pageĂ1Ć3
Main Menu Buttons,
page 2Ć7
CLEAR MENU
Removes Menus
from the Display
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At a Glance
Front Panel Map Ċ
Right Side
Measurement System,
page 3Ć83
Color, page 3Ć10 (TDS 644A)
Display Modes, page 3Ć26
Cursor Measurements, page 3Ć15
Remote Communication, page 3Ć116
Hardcopy, page 3Ć57
File System, page 3Ć53
Saving and Recalling
Waveforms, page 3Ć123
File System, page 3Ć53 (Optional
on TDS 620A & TDS 640A)
Acquisition Modes,
page 3Ć3
Cursor Measurements,
page 3Ć15
Saving and Recalling Setups,
page 3Ć120
Autoset, page 3Ć8
Help, page 3Ć65
Status, page 3Ć130
Selecting Channels,
page 3Ć126
Waveform Math,
page 3Ć148
VerticalControl,
page 3Ć136
Zoom,
page
Ground
Probe Compensation,
page 3Ć100
3Ć151
Horizontal Control,
page 3Ć66
Triggering, page 3Ć132
2Ć4
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At a Glance
Rear Panel Map
GPIB
Centronics Connector
(Optional onTDS 620A (Optional on TDS 620A &
& TDS 640A) TDS 640A)
RSĆ232 Connector
Principal Power Switch,
page 1Ć3
Connector,
page 3Ć116
Fuse,
Serial Number
Power Connector,
page 1Ć3
VGA Output
Rear Panel
Connectors
Security
Bracket
page 1Ć3
(Color with
TDS 644A,
SIGNAL OUTPUT -
Monochrome with
TDS 620A &
(Provides analog signal output)
TDS 640A)
AUX TRIGGER INPUT -
(Provides auxiliary trigger signal input)
MAIN TRIGGER OUTPUT -
(Provides main trigger (TTL) output)
DELAYED TRIGGER OUTPUT -
(Provides delayed trigger (TTL) output)
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At a Glance
Display Map
When present, the general
purpose knob makes coarse
adjustments; when absent,
fine adjustments
The value entered with
the general purpose
knob
The acquisition
status, page 3Ć3
Trigger position(T),
page 3Ć132
The waveform
record icon
Indicates position of
vertical bar cursors in
the waveform record,
page 3Ć136
Shows what part of the waveform
record is displayed, page 3Ć66
Trigger level on
Cursor
waveform (may be
anarrow at right side
of screeninstead of
a bar)
measurements,
page 3Ć15
The side menu
with choices of
specific actions
Channel level
and waveform
source
Trigger
Vertical scale,
page 3Ć136
parameters,
page 3Ć134
Horizontal scale
and time base
type, page 3Ć66
The mainmenu with
choices of major
actions
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At a Glance
To Operate a Menu
1. Press frontĆpanel menu button.
(Press SHIFT first if button
label is blue)
2. Press one of these buttons to
select from main menu.
3. Press one of these buttons to
select from side menu (if
displayed).
4. If side menu item has an adĆ
justable value (shown in reĆ
verse video), adjust it with the
general purpose knob or
keypad.
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At a Glance
To Operate a PopĆUp
Menu
Press
Press here to
remove menus
from screen.
to display popĆups.
Press it again
to make selection.
Alternatively, press SHIFT
first to make selection in
the opposite direction.
A popĆup selection changes the
other main menu titles.
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Ata Glance
Menu Map
Press these buttons:
To bring up these menus:
Acquire Menu
(see page 3Ć3)
Application Menu
(see the Programmer
manual for more details)
Cursor Menu
(see page 3Ć15)
Delayed Trigger Menu
(see page 3Ć20)
Display Menu - Color
(TDS 644A) (see page 3Ć10)
Display Menu - Display
(TDS 644A) (see page 3Ć26)
Display Menu - Display
(TDS 620A & TDS 640A)
(see page 3Ć26)
Horizontal Menu
(see page 3Ć66)
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At a Glance
Press these button
Hardcopy Menu
(TDS 620A & TDS 640A)
(see page 3Ć57)
Hardcopy Menu
(TDS 644A)
(see page 3Ć57)
Main Trigger Menu - Edge
(see page 3Ć32)
Main Trigger Menu - Logic
(see page 3Ć75)
Main Trigger Menu -Pulse
(see page 3Ć109)
Measure Menu
(see page 3Ć83)
More Menu
(see page 3Ć148)
Save/Recall Setup Menu
(see page 3Ć120)
Save/Recall Waveform Menu
(see page 3Ć123)
Status Menu
(see page 3Ć130)
2Ć10
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Ata Glance
Press these buttons:
To bring up these menus:
Utility Menu - Calibration
(see page )
Utility Menu -
Config (see pages )
Utility Menu - Diagnostics
(see the Service manual)
Utility Menu - I/O - GPIB
(seepage3Ć116)
Utility Menu - I/O - RS232
(optional on TDS 620A &
TDS 640A) (seepage3Ć116)
Vertical Channel Menu
(see page 3Ć136)
Zoom Menu
(see page 3Ć151)
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At a Glance
2Ć12
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Triggering
This section describes the edge trigger of the main trigger system and
explores, in a general sense, the topic of triggering. This oscilloscope also
has logic and pulse triggers in the main trigger system and a delayed trigger
system. They are described in Section 3.
Triggers determine when the digitizing oscilloscope starts acquiring and
displaying a waveform. They help create meaningful waveforms from unstaĆ
ble jumbles or blank screens (see Figure 2Ć1).
Triggered Waveform
Untriggered Waveforms
Figure 2Ć1:ăTriggered Versus Untriggered Displays
The trigger event establishes the timeĆzero point in the waveform record,
and all points in the record are located in time with respect to that point. The
digitizing oscilloscope continuously acquires and retains enough sample
points to fill the pretrigger portion of the waveform record (that part of the
waveform that is displayed before, or to the left of, the triggering event on
screen).
When a trigger event occurs, the digitizing oscilloscope starts acquiring
samples to build the posttrigger portion of the waveform record (displayed
after, or to the right of, the trigger event). Once a trigger is recognized, the
digitizing oscilloscope will not accept another trigger until the acquisition is
complete.
The basic trigger is the edge trigger. An edge trigger event occurs when the
trigger source (the signal that the trigger circuit monitors) passes through a
specified voltage level in a specified direction (the trigger slope).
You can derive your trigger from various sources.
Trigger Sources
H
Input channels Ċ the most commonly used trigger source is any one of
the four input channels. The channel you select as a trigger source will
function whether it is displayed or not.
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Triggering
H
H
AC Line Voltage Ċ this trigger source is usefulwhen you are ol oking at
signals related to the power line frequency. Examples include devices
such as lighting equipment and power supplies. Because the digitizing
oscilloscope generates the trigger, you do not have to input a signal to
create the trigger.
Auxiliary Trigger Ċ this trigger source is usefulin digitaldesign and
repair. For example, you might want to trigger with an external clock or
with a signalfrom another part of the circuit. To use the auxiilary trigger,
connect the externaltriggering signalto the Auxiilary Trigger input
connector on the oscilloscope rear panel.
The digitizing oscilloscope provides three standard triggers for the main
trigger system: edge, pulse, and logic. Option 05 provides a video trigger.
The standard triggers are described in individualarticel s found in the ReferĆ
ence section. A brief definition of each type follows:
Types
H
Edge Ċ the basic" trigger. You can use it with both analog and digital
test circuits. An edge trigger event occurs when the trigger source (the
signalthe trigger circuit is monitoring) passes through a specified votlĆ
age level in the specified direction (the trigger slope).
H
H
Pulse Ċ specialtrigger primariyl used on digitalcircuits. Three cal sses
of pulse triggers are width, runt, and glitch. Pulse triggering is available
on the main trigger only.
Logic Ċ special trigger primarily used on digital logic circuits. You select
Boolean operators for the trigger sources. Triggering occurs when the
Boolean conditions are satisfied. There are two kinds of logic triggers,
state and pattern. (Logic triggers are available on the main trigger sysĆ
tem only.)
H
Video Ċ (with option 05) specialtrigger used on video circuits. It hepl s
you investigate events that occur when a video signalgenerates a
horizontalor verticalsync pusl e. Supported cal sses of video triggers
include NTSC, PAL, SECAM, and high definition TV signals.
The trigger mode determines how the oscilloscope behaves in the absence
of a trigger event. The digitizing oscilloscope provides two different trigger
modes, normal and automatic.
Trigger Modes
H
Normal Ċ this trigger mode lets the oscilloscope acquire a waveform
only when it is triggered. If no trigger occurs, the oscilloscope will not
acquire a waveform. (You can push FORCE TRIGGER to force the
oscilloscope to make a single acquisition.)
2Ć14
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Triggering
H
Automatic Ċ this trigger mode (auto mode) lets the oscilloscope acĆ
quire a waveform even if a trigger does not occur. Auto mode uses a
timer that starts after a trigger event occurs. If another trigger event is
not detected before the timer times out, the oscilloscope forces a trigger
anyway. The length of time it waits for a trigger event depends on the
time base setting.
Be aware that auto mode, when forcing triggers in the absence of valid
triggering events, does not sync the waveform on the display. In other
words, successive acquisitions will not be triggered at the same point on the
waveform; therefore, the waveform will appear to roll across the screen. Of
course, if valid triggers occur the display will become stable on screen.
Since auto mode will force a trigger in the absence of one, auto mode is
useful in observing signals where you are only concerned with monitoring
amplitude level. Although the unsynced waveform may roll" across the
display, it will not freeze as it would in normal trigger mode. Monitoring of a
power supply output is an example of such an application.
When a trigger event is recognized, the oscilloscope disables the trigger
system untilacquisition is compel te. In addition, the trigger system remains
disabled during the holdoff period that follows each acquisition. You can set
holdoff time to help ensure a stable display.
Holdoff
For example, the trigger signal can be a complex waveform with many
possible trigger points on it. Though the waveform is repetitive, a simple
trigger might get you a series of patterns on the screen instead of the same
pattern each time.
Digital pulse trains are good examples (see Figure 2Ć2). Each pulse looks
like any other, so many possible trigger points exist. Not all of these will
result in the same display. The holdoff period allows the digitizing oscilloĆ
scope to trigger on the correct edge, resulting in a stable display.
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Triggering
Acquisition
Interval
Acquisition
Interval
Trigger Points
Trigger Level
Holdoff
Holdoff
Triggers are Not Recognized During Holdoff Time
Holdoff
Figure 2Ć2:ăTrigger Holdoff Time Ensures Valid Triggering
Holdoff is settable from 0% (minimum holdoff available) to 100% (maximum
available). To see how to set holdoff, see Mode & Holdoff on page 3Ć35. The
minimum and maximum holdoff varies with the horizontal scale. See Holdoff,
Variable, MainTrigger in the TDS 620A, 640A, & 644A Performance VerificaĆ
tionManual , Section 2 on Specification, Typical Characteristics for typical
minimum and maximum values.
Trigger coupling determines what part ofthe signal is passed to the trigger
circuit. Available coupling types include AC, DC, Low Frequency Rejection,
High Frequency Rejection, and Noise Rejection:
Coupling
H
H
DC coupling passes all ofthe input signal. In other words, it passes both
AC and DC components to the trigger circuit.
AC coupling passes only the alternating components ofan input signal.
(AC components above 10 Hz are passed ifthe source channel is in
1 MW coupling; above 200 kHz are passed in 50 W coupling.) It removes
the DC components from the trigger signal.
H
High frequency rejection removes the high frequency portion of the
triggering signal. That allows only the low frequency components to
pass on to the triggering system to start an acquisition. High frequency
rejection attenuates signals above 30 kHz.
H
H
Low frequency rejection does the opposite ofhigh frequency rejection.
Low frequency rejection attenuates signals below 80 kHz.
Noise Rejection lowers trigger sensitivity. It requires additional signal
amplitude for stable triggering, reducing the chance of falsely triggering
on noise.
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Triggering
The adjustable trigger position defines where on the waveform record the
Trigger Position
trigger occurs. It lets you properly align and measure data within records.
The part of the record that occurs before the trigger is the pretrigger portion.
The part that occurs after the trigger is the posttrigger portion.
To help you visualize the trigger position setting, the top part of the display
has an icon indicating where the trigger occurs in the waveform record. You
select in the Horizontal menu what percentage of the waveform record will
contain pretrigger information.
Many users find displaying pretrigger information a valuable troubleshooting
technique. For example, if you are trying to find the cause of an unwanted
glitch in your test circuit, it may prove valuable to trigger on the glitch and
make the pretrigger period large enough to capture data before the glitch.
By analyzing what happened before the glitch, you may uncover clues about
the source of the glitch.
The slope control determines whether the oscilloscope finds the trigger point
on the rising or the falling edge of a signal (see Figure 2Ć3).
Slope and Level
You set trigger slope by selecting Slope in the Main Trigger menu and then
selecting from the rising or falling slope icons in the side menu that appears.
The level control determines where on that edge the trigger point occurs
(see Figure 2Ć3).
PositiveĆGoing Edge
NegativeĆGoing Edge
Trigger Level Can be
Adjusted Vertically
Trigger Slope Can be Positive or Negative
Figure 2Ć3:ăSlope and Level Controls Help Define the Trigger
The digitizing oscilloscope lets you set the main trigger level with the trigger
MAIN LEVEL knob.
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Triggering
As mentioned earlier in this section there is also a delayed trigger system
that provides an edge trigger (no pulse or logic triggers). When using the
delayed time base, you can also delay the acquisition of a waveform for a
userĆspecified time ora userĆspecified numberof delayed triggerevents (or
both) aftera main triggerevent.
Delayed Trigger
See Delayed Triggering, on page 3Ć20.
See Edge Triggering, on page 3Ć32.
See Horizontal Controls, on page 3Ć66.
See Logic Triggering, on page 3Ć75.
See Pulse Triggering, on page 3Ć109.
See Triggering, on page 3Ć132.
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Acquisition
Acquisition is the process of sampling the analog input signal, converting it
into digital data, and assembling it into a waveform record. The oscilloscope
creates a digital representation of the input signal by sampling the voltage
level of the signal at regular time intervals (Figure 2Ć4).
+5.0 V
+5.0 V
0 V
0 V
0 V
0 V
-5.0 V
-5.0 V
Digital Values
Input Signal
Sampled Points
Figure 2Ć4:ăAcquisition: Input Analog Signal, Sample, and Digitize
The sampled points are stored in memory along with corresponding timing
information. You can use this digital representation of the signal for display,
measurements, or further processing.
You specify how the digitizing oscilloscope acquires data points and asĆ
sembles them into the waveform record.
The trigger point marks time zero in a waveform record. All record points
before the trigger event make up the pretrigger portion of the the waveform
record. Every record point after the trigger event is part of the posttrigger
portion. All timing measurements in the waveform record are made relative
to the trigger event.
Sampling and
Digitizing
Each time it takes a sample, the oscilloscope digitizer produces a numeric
representation of the signal.
The digitizer can use the extra samples to perform additional processing,
such as averaging or looking for minimum and maximum values.
The digitizing oscilloscope creates a waveform record containing a userĆspeĆ
cified number of data points. Each record point represents a certain voltage
level that occurs a determined amount of time from the trigger event.
Record Length
The number of points that make up the waveform record is defined by the
record length. You can set the record length in the Horizontal menu. The
digitizing oscilloscope provides record lengths of 500, 1000, and 2000
points.
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Acquisition
Sampling
Sampling is the process of converting the analog input signal to digital for
display and processing (see Figure 2Ć5).
Record Points
Sampling Rate
Figure 2Ć5:ăRealĆTime Sampling
Interpolation
Turning the horizontal SCALE knob clockwise causes the scope to assign
shorter time periods to the waveform record. The smaller the time period
gets, the faster the oscilloscope needs to acquire record points to fill up the
record.
If you turn the horizontal SCALE knob to a point that the time base is faster
than 25Ăns, the digitizing oscilloscope will not acquire enough samples for a
complete waveform record. When that happens, the digitizing oscilloscope
uses a process called interpolation to create the intervening points in the
waveform record. There are two options for interpolation: linear or sin(x)/x.
Linear interpolation computes record points between actual acquired samĆ
ples by using a straight line fit. It assumes all the interpolated points fall in
their appropriate point in time on that straight line. Linear interpolation is
useful for many waveforms such as pulse trains.
Sin(x)/x interpolation computes record points using a curve fit between the
actual values acquired. It assumes all the interpolated points fall along that
curve. That is particularly useful when acquiring more rounded waveforms
such as sine waves. Actually, it is appropriate for general use, although it
may introduce some overshoot or undershoot in signals with fast rise times.
NOTE
When using either type of interpolation, you may wish to set the
display style so that the real samples are displayed intensified
relative to the interpolated samples. The instructions under Display
Style on page 3Ć26 explain howto turn on intensified samples.
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Acquisition
The digitizing oscilloscope supports three acquisition modes:
Acquisition Modes
H
H
H
Sample
Envelope
Average
Bandwidth refers to the range of frequencies that an oscilloscope can acĆ
quire and display accurately (that is, with less than 3 dB attenuation).
Bandwidth
Coupling
You can set different bandwidths with the digitizing oscilloscope. Lower
bandwidth settings let you eliminate the higher frequency components of a
signal. The TDS 600A series offers Full (500 MHz), 100 MHz, and 20ĂMHz
bandwidth settings.
You can couple your input signal to the digitizing oscilloscope three ways.
You can choose between AC, DC, or Ground (GND). You can also set the
input impedance.
H
H
H
DC couplingshows both the AC and DC components of an input signal.
AC couplingshows only the alternatingcomponents of an input signal.
Ground (GND) couplingdisconnects the input signal from the acquisiĆ
tion.
H
Input impedance lets you select either 1ĂMW or 50 WĂ impedance.
NOTE
If you select 50 WĂimpedance with AC coupling, the digitizing
oscilloscope will not accurately display frequencies under 200ĂkHz.
Also, the optional P6205 probe automatically switches the input
coupling to 50 W. This setting is appropriate for active probes like
the P6205. If changing to a passive probe, or using any input signal
that is not from a 50 W system, be sure to switch the channel input
coupling to 1 MW.
See Scaling and Positioning Waveforms, on page 2Ć22.
For More
Information
See AcquisitionModes , on page 3Ć3.
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Scaling and Positioning Waveforms
Scaling and positioning waveforms means increasing or decreasing their
displayed size and moving them up, down, right, and left on the display.
Two display icons, the channel reference indicator and the record view, help
you quickly see the position of the waveform in the display (see Figure 2Ć6).
The channel reference icon points to the ground of the waveform record
when offset is set to 0ĂV. This is the point about which the waveform conĆ
tracts or expands when the vertical scale is changed. The record view, at the
top of the display, indicates where the trigger occurs and what part of the
waveform record is displayed.
Record View
Channel Reference Icon
Original Position
Positioned Vertically
Positioned Horizontally
Original Scale
Scaled Vertically
Scaled Horizontally
Figure 2Ć6:ăScaling and Positioning
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Scaling and Positioning Waveforms
You can adjust the vertical position of the selected waveformby moving it up
or down on the display. For example, when trying to compare multiple
waveforms, you can put one above another and compare them, or you can
overlay the two waveforms on top of each other. To move the selected
waveformturn the vertical POSITION knob.
Vertical System
You can also alter the vertical scale. The digitizing oscilloscope shows the
scale (in volts per division) for each active channel toward the bottomleft of
the display. As you turn the vertical SCALE knob clockwise, the value deĆ
creases resulting in higher resolution because you see a smaller part of the
waveform. As you turn it counterĆclockwise the scale increases allowing you
to see more of the waveform but with lower resolution.
Besides using the position and scale knobs, you can set the vertical scale
and position with exact numbers. You do that with the Vertical menu Fine
Scale and Position selections and the general purpose knob and/or the
keypad.
Offset
Vertical offset changes where the channel reference indicator is shown with
respect to the graticule. Offset adds a voltage to the reference indicator
without changing the scale. That feature allows you to move the waveform
up and down over a large area without decreasing the resolution.
Offset is useful in cases where a waveformhas a DC bias. One example is
looking at a small ripple on a power supply output. You may be trying to
look at a 100 mV ripple on top of a 15 V supply. The range available with
offset can prove valuable as you try to move and scale the ripple to meet
your needs.
Adjusting the horizontal position of waveforms moves them right or left on
the display. That is useful when the record length of the waveformis so large
(greater than 500 points) that the digitizing oscilloscope cannot display the
entire waveformrecord at one time. You can also adjust the scale of the
waveform. For example, you might want to see just one cycle of a waveform
to measure the overshoot on its rising edge.
Horizontal System
You adjust the horizontal scale of the displayed waveformrecords using the
horizontal SCALE knob and the horizontal position using the horizontal
POSITION knob.
The digitizing oscilloscope shows the actual scale in the bottomright of the
display. The scale readout shows the time per division used. Since all live
waveforms use the same time base, the digitizing oscilloscope only displays
one value for all the active channels.
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Scaling and Positioning Waveforms
Aliasing
When aliasing happens, you see a waveform with a frequency lower than
the actual waveform being input or a waveform is not stable even though the
light next to TRIG'D is lit. Aliasing occurs because the oscilloscope cannot
sample the signal fast enough to construct an accurate waveform record
(Figure 2Ć7).
Actual HighĆFrequency Waveform
Apparent LowĆFrequency
Waveform Due to Aliasing
Sampled Points
Figure 2Ć7:ăAliasing
One simple way to check for aliasing is to slowly change the horizontal scale
(time per division setting). If the shape of the displayed waveform changes
drastically, you may have aliasing.
In order to represent a signal accurately and avoid aliasing, you must samĆ
ple the signal more than twice as fast as the highest frequency component.
For example, a signal withfrequency components of 500ĂMHz would need
to be sampled at a rate faster than 1 Gigasamples/second.
There are various ways to prevent aliasing. Try adjusting the horizontal
scale, or simply press the AUTOSET button. You can also counteract some
aliasing by changing the acquisition mode in the Acquisition menu. For
example, if you are using the sample mode and suspect aliasing, you may
want to change to the envelope mode. Since the envelope mode searches
for multiple acquisitions with the highest and lowest values, it can detect
faster signal components over time.
Delayed Time Base
You can set a main time base and a delayed time base. Eachtime base has
its own trigger. There are two types of delayed time base acquisitions. Each
type is based on its triggering relationship to the main time base. These are
delayed runs after main and delay triggerable (after time, events, or both)
acquisitions.
The delayed time base is useful in displaying events that follow other events.
See Triggering on page 2Ć13 for more information on the delayed trigger.
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Scaling and Positioning Waveforms
You can use zoom to see more detail without changing the acquired signal.
When you press the ZOOM button, a portion of the waveform record can be
expanded or compressed on the display, but the record points stay the
same.
Zoom
Zoom is very useful when you wish to temporarily expand a waveform to
inspect small feature(s) on that waveform. For example, you might use zoom
to temporarily expand the front corner of a pulse to inspect its aberrations.
Use zoom to expand it horizontally and vertically. After you are finished, you
can return to your original horizontal scale setting by pressing one menu
button. (The zoom feature is also handy if you have acquired a waveform
while using the fastest time per division and want to further expand the
waveform horizontally.)
Autoset lets you quickly obtain a stable waveform display. It automatically
adjusts a wide variety of settings including vertical and horizontal scaling.
Other settings affected include trigger coupling, type, position, slope, and
mode and display intensities. Autoset on page 3Ć8 describes in detail what
autoset does.
Autoset
See Autoset, on page 3Ć8.
For More
Information
See Delayed Triggering, on page 3Ć20.
See Horizontal Control, on page 3Ć66.
See Vertical Control, on page 3Ć136.
See Zoom, on page 3Ć151.
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Measurements
The digitizing oscilloscope not only displays graphs of voltage versus time, it
also can help you measure the displayed information (see Figure 2Ć8).
Cursor
Automated
Readouts
Measurements
Graticule
D: 64.0ĂmV
Ch 1
@: 32.0ĂmV
Frequency
100ĂMHz
Ch 1 Period
10Ăns
Cursors
Figure 2Ć8:ăGraticule, Cursor and Automated Measurements
The oscilloscope provides three measurement classes. They are: autoĆ
mated, cursors, and graticule measurements.
Measurement
Sources
Automated Measurements
You make automated measurements merely by pressing a few buttons. The
digitizing oscilloscope does all the calculating for you. Because these meaĆ
surements use the waveform record points, automated measurements are
more accurate than cursor or graticule measurements.
Press the MEASURE button for the automated measurement menus. These
menus let you make amplitude (typically in volts; sometimes in %), time
(typically in seconds or hertz), and area (in voltĆseconds) measurements.
You can select and display up to four measurements at a time. (See
Table 3Ć4 on page 3Ć83 for a list of all the automatic measurements and their
definitions.)
You can make automated measurements on the entire waveform record or
just on a specific part. The gating selection in the Measurement menu lets
you use the vertical cursors to limit the measurement to a section of the
waveform record.
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Measurements
The snapshot selection in the Measurement menu lets you display almost all
of the measurements at once. You can read about snapshot under Snapshot
of Measurements, onpage 3Ć92.
Automated measurements use readouts to show measurement status.
These readouts are updated as the oscilloscope acquires new data or if you
change settings.
Cursor Measurements
Cursors are fast and easyĆtoĆunderstand measurements. You take measureĆ
ments by moving the cursors and reading their numeric values from the on
screenreadouts, which update as you adjust the positionof the cursors.
Cursors appear inpairs. One cursor is active and the other inactive. You
move the active cursor (the solid line) using the general purpose knob. The
SELECT buttonlets you select (toggle) which cursor bar is active or inactive.
The inactive cursor is a dashed line on the display.
To get the cursor menu, press the CURSOR button. There are three kinds of
cursors available inthat menu:
H
H
Horizontal bar cursors measure vertical parameters (typically volts).
Vertical bar cursors measure horizontal parameters (typically time or
frequency).
H
Paired cursors measure both vertical parameters (typically volts) and
horizontal parameters (typically time or frequency).
There are also two modes for cursor operationavailable inthe cursor meĆ
nu Ċ independent and tracking (See Figure 2Ć9).
Independent Mode
Tracking Mode
Only Selected Cursor
Moves
Both Cursors Move
in Tandem
Figure 2Ć9:ăCursor Modes
H
Independent mode cursors operate as was earlier described; that is, you
move one cursor at a time (the active cursor) using the general purpose
knob, and you use the SELECT buttonto toggle which cursor is active.
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Measurements
H
Tracking mode cursors operate in tandem: you move both cursors at the
same time using the general purpose knob. To adjust the solid cursor
relative to the dashed cursor, you push the SELECT button to suspend
cursor tracking and use the general purpose knob to make the adjustĆ
ment. A second push toggles the cursors back to tracking.
You can read more detailed information about how to use cursors in Cursor
Measurements, beginning on page 3Ć15.
Graticule Measurements
Graticule measurements provide you with quick, visual estimates. For examĆ
ple, you might look at a waveform amplitude and say it is a little more than
100ĂmV."
You can perform simple measurements by counting the number of major
and minor graticule divisions involved and multiplying by the scale factor.
For example, if you counted five major vertical graticule divisions between
the minimum and maximum values of a waveform and knew you had a scale
factor of 100ĂmV/division, then you could easily calculate your peakĆtoĆpeak
voltage:
5 divisions × 100ĂmV/division = 500ĂmV.
NOTE
AUX 1 and AUX 2 (TDS 620A) can not be set to the volts per division
needed to match video graticules.
When you select the NTSC graticule, the volts per division of all selected
channels is set to 143 mV/div (152 mV/div for PAL) where the divisions are
those of the conventional graticule, not the divisions of the video graticules.
For NTSC, the actual grid lines represent 10 IRE, and for PAL the lines are
100 mV apart.
See Appendix B: Algorithms, on page AĆ7, for details on how the digitizing
oscilloscope calculates each automatic measurement.
For More
Information
See Cursor Measurements, on page 3Ć15, for more information on cursor
measurements.
See Measurement System, on page 3Ć83, for more information on automatic
measurements.
See Tutorial Example 3: Automated Measurements, on page 1Ć18, for more
information on automatic measurements.
See Waveform Math, on page 3Ć148, for using cursors to measure math
waveforms.
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Overview
This section describes the details of operating the digitizing oscilloscope. It
contains an alphabetical list of tasks you can perform with the digitizing
oscilloscope. Use this section to answer specific questions about instrument
operation. These tasks include:
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
Acquisition Modes
Autoset
H
H
H
H
H
H
Probe Compensation
Probe Selection
Color
Pulse Triggering
Cursor Measurements
Delayed Triggering
Display Modes
Edge Triggering
Fast Fourier Transforms
File System
Remote Communication
Saving and Recalling Setups
Saving and Recalling WaveĆ
forms
H
H
H
H
H
H
H
H
H
Selecting Channels
SignalPath Compensation
Status
Hardcopy
Triggering
Help
VerticalControl
Waveform Differentiation
Waveform Integration
Waveform Math
Zoom
HorizontalControl
Limit Testing
Logic Triggering
Measurement System
Probe Cal
Many of these tasks list steps you perform to accomplish the task. You
should read Conventions on page ii of Welcome before reading about these
tasks.
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Overview
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Acquisition Modes
The acquisition system has several options for converting analog data into
digital form. The Acquisition menulets youdetermine the acquisition mode
and how to start and stop acquisitions.
The digitizing oscilloscope supports three acquisition modes.
Description of Modes
H
H
H
Sample
Envelope
Average
Sample mode operates in realĆtime on a single trigger event, provided the
digitizing oscilloscope can acquire enough samples for each trigger event.
Envelope and average modes operate on multiple acquisitions. The digitizĆ
ing oscilloscope averages or envelopes several waveforms on a pointĆbyĆ
point basis.
Figure 3Ć1 illustrates the different modes and lists the benefits of each. It will
help youselect the appropriate mode for your application.
Sample Mode
In Sample mode, the oscilloscope creates a record point by saving the first
sample (of perhaps many) during each acquisition interval. (An acquisition
interval is the time covered by the waveform record divided by the record
length.) This is the default mode.
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Acquisition Modes
Acquisition
Mode
Waveform Drawn
on CRT
Takes One Acquisition per Trigger
Sample
Uses first sample in
each interval over
single acquisition
This is the default mode.
Acquisition
Mode
Waveform Drawn
on CRT
Takes a UserĆSpecified Number of Acquisitions per Trigger
Acquisition 1
2
3
Envelope
Finds highest and
lowest record points over
many acquisitions
Uses Sample Mode for Each Acquisition
Use to reveal variations in
the signal across time.
Average
Calculates average value for
each record point over many
acquisitions
Uses Sample Mode for Each Acquisition
Use to reduce apparent noise
in a repetitive signal.
Figure 3Ć1:ăHow the Acquisition Modes Work
Envelope Mode
Envelope mode lets you acquire and display a waveform record that shows
the extremes in variation over several acquisitions. You specify the number
of acquisitions over which to accumulate the data. The oscilloscope saves
the highest and lowest values in two adjacent intervals. Envelope mode
gathers peaks over many trigger events.
After each trigger event, the oscilloscope acquires data and then compares
the min/max values from the current acquisition with those stored from
previous acquisitions. The final display shows the most extreme values for
all the acquisitions for each point in the waveform record.
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Acquisition Modes
Average Mode
Average mode lets you acquire and display a waveform record that is the
averaged result of several acquisitions. This mode reduces random noise.
The oscilloscope acquires data after each trigger event using Sample mode.
It then averages the record point from the current acquisition with those
stored from previous acquisitions.
The acquisition readout at the top of the display (Figure 3Ć2) shows the state
of the acquisition system (running or stopped). The running" state shows
the sample rate and acquisition mode. The stopped" state shows the
numberof acquisitions acquired since the last stop ormajorchange.
Acquisition Readout
Acquisition Readout
Figure 3Ć2:ăAcquisition Menu and Readout
To bring up the acquisition menu (Figure 3Ć2) press SHIFT ACQUIRE
MENU.
Operation
Acquisition Mode
To choose how the digitizing oscilloscope will create points in the waveform
record:
Press SHIFT ACQUIRE MENU ➞ Mode (main) ➞ Sample, Envelope, or
Average (side).
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AcquisitionModes
When you select Envelope or Average, you can enter the number of waveĆ
form recordsto be enveloped or averaged using the keypad or the general
purpose knob.
NOTE
The digitizing oscilloscope interpolates between samples at horiĆ
zontal scale settings faster than 25 ns/div. See Sampling and
Digitizing on page 2Ć19 for a discussion of interpolation.
Stop After
You can choose to acquire exactly one waveform sequence or to acquire
waveformscontinuously under manual control.
Press SHIFT ACQUIRE MENU ➞ Stop After (main) ➞ RUN/STOP button
only, Single Acquisition Sequence, or Limit Test Condition Met (side)
(see Figure 3Ć3).
Figure 3Ć3:ăAcquire Menu Ċ Stop After
H
RUN/STOP buttononly (side) lets you start or stop acquisitions by
toggling the RUN/STOP button. Pressing the RUN/STOP button once
will stop the acquisitions. The upper left hand corner in the display will
say Stopped and show the number of acquisitions. If you press the
button again, the digitizing oscilloscope will resume taking acquisitions.
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Acquisition Modes
H
H
Press Single Acquisition Sequence (side). That selection lets you run a
single sequence of acquisitions by pressing the RUN/STOP button. In
Sample mode, the digitizing oscilloscope will acquire a waveform record
with the first valid trigger event and stop.
In Envelope or Average mode, the digitizing oscilloscope will make the
specified number of acquisitions to complete the averaging or envelopĆ
ing task.
Hint: To quickly select Single Acquisition Sequence without displaying
the Acquire and Stop After menus, press SHIFT FORCE TRIG. Now the
RUN/STOP button operates as just described. (You still must display the
Acquire menu and then the Stop After menu to leave Single Acquisition
Sequence operation.)
Limit Test Condition Met (side) lets you acquire waveforms until waveĆ
form data exceeds the limits specified in the limit test. Then acquisition
stops. At that point, you can also specify other actions for the oscilloĆ
scope to take, using the selections available in the Limit Test Setup
main menu.
NOTE
In order for the digitizing oscilloscope to stop an acquisition when
limit test conditions have been met, limit testing must be turned
ON, using the Limit Test Setup main menu.
Setting up limit testing requires several more steps. You can create the
template waveform against which to compare incoming waveforms,
using the Create Limit Test Template main menu item. You can then
specify that the comparison is to be made, and the channel to compare
against the template, using the Limit Test Sources main menu item.
See Acquisition, on page 2Ć19.
For More
Information
See Limit Testing, on page 3Ć70.
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Autoset
The autoset functionlets you quickly obtainand display a stable waveform
of usable size. Autoset automatically sets up the front panel controls based
on the characteristics of the input signal. It is much faster and easier than a
manual controlĆbyĆcontrol setup.
Autoset makes adjustments in these areas:
H
H
H
H
H
Acquisition
Display
Horizontal
Trigger
Vertical
NOTE
Autoset may change vertical position in order to position the waveĆ
form appropriately. It always sets vertical offset to 0 V.
1. Press the Channel Selection button (such as CH 1) corresponding to
Operation
your input channel to make it active.
2. Press AUTOSET.
If you use autoset when one or more channels are displayed, the digitizing
oscilloscope selects the lowest numbered channel for horizontal scaling and
triggering. Vertically, all channels in use are individually scaled.
If you use autoset when no channels are displayed, the digitizing oscilloĆ
scope will turn on channel one (CH 1) and scale it.
Table 3Ć1 onthe following page lists the autoset defaults.
Autoset Defaults
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Autoset
TableĂ3Ć1:ăAutoset Defaults
Changed by Autoset to
Control
Selected channel
Numerically lowest of the displayed
channels
Acquire Mode
Acquire Stop After
Display Style
Sample
RUN/STOP button only
Vectors
Display Intensity Ċ Overall
(TDS 640A & TDS 620A)
If less than 50%, set to 75%
Display Format
YT
Horizontal Position
Horizontal Scale
Centered within the graticule window
As determined by the signal frequenĆ
cy
Horizontal Time Base
Horizontal Record Length
Limit Test
Main Only
Unchanged
Off
Trigger Position
Trigger Type
Unchanged
Edge
Trigger Source
Numerically lowest of the displayed
channels (the selected channel)
Trigger Level
Midpoint of data for the trigger source
Trigger Slope
Trigger Coupling
Trigger Holdoff
Vertical Scale
Vertical Coupling
Positive
DC
0
As determined by the signal level
DC unless AC was previously set.
AC remains unchanged.
Vertical Bandwidth
Vertical Offset
Zoom
Full
0 volts
Off
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Color (TDS 644A)
The TDS 644A can display information in different colors. The Color menu
lets you choose palettes of colors and decide what colors to assign to what
pieces of information.
To bring up the Color menu:
Operation
1. Press DISPLAY toshow the Display menu.
2. Press Settings in the main menu until you select Color from the popĆup
menu (see Figure 3Ć4).
Figure 3Ć4:ăDisplay Menu Ċ Setting
Color lets you alter color settings for various display components such as
waveforms and text. Display lets you adjust the style, intensity level, gratiĆ
cule, and format features. For more information on display, see Display on
page 3Ć26.
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Color
Choose Palette
You can choose a palette of 13 colors from a menu of preĆset palettes.
1. Choose the starting palette by selecting Palette from the main menu.
2. Select one of the available palettes in the side menu. Choose from
Normal, Bold, Hardcopy Preview or Monochrome.
3. If you are using a persistence display and wish to vary the color of each
point depending on its persistence, choose Persistence Palettes. Then
choose Temperature, Spectral, o rGray Scale from the resulting side
menu. Choose View Palette to preview your selection on the display.
Press Persistence Palette toquit preview mode. Press Clear Menu to
return tothe Palette menu.
NOTE
Use at higher room temperatures or with higher intensity display
formats, such as the white fields in the Hardcopy Preview palette,
can temporarily degrade display quality.
You can select the Hardcopy Preview palette when using certain
color hardcopy formats. The default colors in the hardcopy preview
palette comprise a white background and fully saturated primary
colors which generally produce the best result.
Change Palette Colors
You can change the current palette colors. You do this by selecting a color
and varying its hue, lightness, and saturation. Hue is the wavelength of light
reflected from the surface. It varies continuously along the color spectrum as
produced by a rainbow. Lightness refers to the amount of light reflected from
the surface. It varies from black, to the nominal color, to white. Saturation is
the intensity of color. Completely desaturated color is gray. Completely
saturated color of any hue is that color at its most intense level.
1. Select the main menu Change Colors item (see Figure 3Ć5).
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Color
ScrTxt
Figure 3Ć5:ăDisplay Menu Ċ Palette Colors
2. Select one of the 13 colors by pressing (repeatedly) Color in the side
menu.
3. If you want to use the factory default for this color, press the side menu
Reset to Factory Color.
4. Choose Hue from the side menu and use the general purpose knob or
keypad to select the desired hue. Values range from 0 to 359. Sample
values are: 0 = blue, 60 = magenta, 120 = red, 180 = yellow, 240 =
green, and 360 = cyan.
5. Choose Lightness from the side menu and use the general purpose
knob or keypad to select the lightness you desire. A value of 0 results in
black. A value of 50 provides the nominal color. A value of 100 results in
white.
6. Choose Saturation from the side menu and use the general purpose
knob or keypad to select the saturation you desire. A value of 100
provides a pure color. A value of 0 provides gray.
Set Math Waveform Color
To define math waveform colors:
1. Choose to define math waveform colors by selecting the main menu
Map Math item.
2. Select one of the three math waveforms by pressing Math in the side
menu.
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Color
3. If you want to assign the selected math waveform to a specific color,
press Color and cycle through the choices.
4. If you want the selected math waveform to be the same color as the
waveform it is based on, select Color Matches Contents. If the math
waveform is based on dual waveforms, the math waveform will use the
color of the first constituent waveform.
To return to the factory defaults, select Reset to Factory Color.
Set Reference Waveform Color
To define reference waveform colors:
1. Press MapReference in the main menu (see Figure 3Ć6).
2. Select one of the four reference waveforms by pressing Ref in the side
menu.
3. To assign the selected reference waveform to a specific color, press
(repeatedly) Color and choose the value.
4. To make the selected reference waveform the same color as the waveĆ
form it is based on, select Color Matches Contents.
To return to the factory defaults, select Reset to Factory Color.
Figure 3Ć6:ăDisplay Menu Ċ Map Reference Colors
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Color
SelectOptions
To define what color to show where a waveform crosses another waveform:
1. Press the Options main menu item.
2. Select that you wish to use a special color to mark collision zones by
toggling Collision Contrast in the side menu to ON.
Restore Colors
To restore colors to their factory default settings:
1. Press the main menu Restore Colors item (see Figure 3Ć7).
2. Select what you wish to restore by pressing Reset Current Palette To
Factory, Reset All Palettes To Factory or ResetAll Mappings To
Factory in the side menu.
Figure 3Ć7:ăDisplay Menu Ċ Restore Colors
See Display Modes, on page 3Ć26.
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Cursor Measurements
Use the cursors to measure the difference (either in time or voltage) beĆ
tween two locations in a waveformrecord.
Cursors are made up of two markers that you position with the general
purpose knob. You move one cursor independently or both cursors in
tandem, depending on the cursor mode. As you position the cursors, readĆ
outs on the display report measurement information.
Description
There are three cursor types: horizontal bar, vertical bar, and paired (FigĆ
ure 3Ć8).
Horizontal bar cursors measure vertical parameters (typically volts).
Vertical bar cursors measure horizontal parameters (typically time or freĆ
quency).
Horizontal Bar Cursors
Vertical Bar Cursors
Paired Cursors
Figure 3Ć8:ăCursor Types
Paired cursors measure both vertical parameters (typically volts) and horiĆ
zontal parameters (typically time) simultaneously.
Look at Figure 3Ć8. Note that each of the two paired cursors has a long
vertical bar paired with an X. The Xs measures vertical parameters (typically
volts); the long vertical bars measure horizontal parameters (typically time or
frequency). (See Cursor Readouts on page 3Ć16 for more information.)
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Cursor Measurements
NOTE
When cursors measure certain math waveforms, the measurement
may not be of time, frequency, or voltage. Cursor measurement of
those math waveforms that are not of time, frequency, or voltage is
described in Waveform Math, which begins on page 3Ć148.
There are two cursor modes: independent and tracking (see Figure 3Ć9).
Independent Mode
Tracking Mode
Only Selected Cursor
Moves
Both Cursors Move
in Tandem
Figure 3Ć9:ăCursor Modes
In independent mode you move only one cursor at a time using the general
purpose knob. The active, or selected, cursor is a solid line. Press SELECT
to change which cursor is selected.
In tracking mode you normally move both cursors in tandem using the
generalpurpose knob. The two cursors remain a fixed distance (time or
voltage) from each other. Press SELECT to temporarily suspend cursor
tracking. You can then use the generalpurpose knob to adjust the distance
of the solid cursor relative to the dashed cursor. A second push toggles the
cursors back to tracking.
The cursor readout shows the absolute location of the selected cursor and
the difference between the selected and nonĆselected cursor. The readouts
differ depending on whether you are using H Bars or V Bars.
Cursor Readouts
H
H Bars: the value after D shows the voltage difference between the
cursors. The value after @ shows the voltage of the selected cursor
relative to ground (see Figure 3Ć10). With the video trigger option, you
can also display the voltage in IRE units.
H
V Bars: the value after D shows the time (or frequency) difference beĆ
tween the cursors. The value after @ shows the time (frequency) of the
selected cursor relative to the trigger point. With the video trigger option,
you can also display the line number.
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Cursor Measurements
In FastFrame mode, the @ shows the time position of the selected
cursor relative to the trigger point of the frame that the selected cursor is
in. The D shows the time difference between the two cursors only if both
cursors are in the same frame.
H
Paired: the value after one D shows the voltage difference between the
the two Xs; the other D shows the time (or frequency) difference beĆ
tween the two long vertical bars. The value after @ shows the voltage at
the X of the selected cursor relative to ground (see Figure 3Ć11).
In FastFrame mode, the D shows the time difference between the two
cursors only if both cursors are in the same frame.
Cursor Readout (H Bars)
NonĆselected Cursor
(Dashed Line)
Selected Cursor
(Solid Line)
Figure 3Ć10:ăH Bars Cursor Menu and Readouts
Paired cursors can only show voltage differences when they remain on
screen. If the paired cursors are moved off screen horizontally, Edge will
replace the voltage values in the cursor readout.
To take cursor measurements, press CURSOR to display the Cursor menu
(Figure 3Ć10).
Operation
Function
Select the type of cursors you want using the Function menu item:
Press CURSOR ➞ Function (main) ➞ H Bars, V Bars, Paired, or Off (side).
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Cursor Measurements
Position of Vertical Bar Cursors
(Useful for Locating Cursors
Outside the Display)
Cursor Readout (Paired)
NonĆselected Cursor
(Dashed Vertical Bar)
Selected Cursor
(Solid Vertical Bar)
Figure 3Ć11:ăPaired Cursor Menu and Readouts
Mode
Select the cursor mode you want using the Mode menu item.
1. Press CURSOR ➞ Mode (main) ➞ Independent or Tracking (side):
H
H
Independent makes each cursor positionable without regard to the
position of the other cursor.
Tracking makes both cursors positionable in tandem; that is, both
cursors move in unison and maintain a fixed horizontal or vertical
distance between each other.
2. Use the general purpose knob to move the selected (active) cursor if
Independent was selected in step 1. Press SELECT to change which
cursor is active and moves. A solid line indicates the active cursor, and a
dashed line the inactive cursor.
or
Use the general purpose knob to move both cursors in tandem if TrackĆ
ing was selected in step 1. Press SELECT to temporarily suspend
cursor tracking; then use the general purpose knob to adjust the disĆ
tance of the solid cursor relative to the dashed cursor. Press SELECT
again to resume tracking. A solid line indicates the adjustable cursor
and a dashed line the fixed cursor.
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Cursor Measurements
Time Units
You can choose to display vertical bar cursor results in units of time or
frequency. If you have Option 5 Video, you can also display the results in
terms of video line number.
Press CURSOR ➞ Time Units (main) ➞ seconds or 1/seconds (Hz) or,
with Option 5, video line number (side).
Amplitude Units
If you are measuring NTSC signals, you can choose to display vertical
readings in IRE units. If you are trying to do this, you should have option 05
Video Trigger installed as it would be difficult to trigger on composite video
waveforms without option 05.
Press CURSOR ➞ Amplitude Units (main) ➞ IRE (NTSC)
To return to normal:
Press CURSOR ➞ Amplitude Units (main) ➞ Base
Cursor Speed
You can change the cursors speed by pressing SHIFT before turning the
general purpose knob. The cursor moves faster when the SHIFT button is
lighted and the display reads Coarse Knobs in the upper right corner.
See Measurements, on page 2Ć26.
For More
Information
See Waveform Math, on page 3Ć148, for information on cursor units with
multiplied waveforms.
See Fast Fourier Transforms on page 3Ć36, Waveform Differentiation on
page 3Ć139, and Waveform Integration on page 3Ć143, if your oscilloscope is
equipped with Option 2F Advanced DSP Math (standard on the TDS 644A),
for information on cursor units with integrated, differentiated, and FFT waveĆ
forms.
See the TDS FamilyOption 05 Video Trigger Interface, if your oscilloscope is
equipped with the video trigger option, for information on cursor units with
video waveforms.
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Delayed Triggering
The TDS 600A Series oscilloscopes provide a main time base and a delayed
time base. The delayed time base, like the main time base, requires a trigger
signal and an input source dedicated to that signal. You can only use delay
with respect to the main edge trigger and certain classes of main pulse
triggers.
There are two different ways to delay the acquisition of waveforms: delayed
runs after main and delayed triggerable. Only delayed triggerable uses the
delayed trigger system.
Delayed runs after main looks for a main trigger, then waits a userĆdefined
time, and then starts acquiring (see Figure 3Ć12).
Wait for
Main
Trigger
Wait
UserĆSpecified
Time
Acquire
Data
Figure 3Ć12:ăDelayed Runs After Main
Delayed triggerable looks for a main trigger and then, depending on the
type of delayed trigger selected, makes one of the three types of delayed
triggerable mode acquisitions listed below (see Figure 3Ć13).
Wait for
Wait for
Main
Trigger
Wait
UserĆSpecified
Time
Delayed
Trigger
Event
Acquire
Data
Delayed Triggerable
After Time
Wait the
UserĆSpecified
Number of
Delayed Trigger
Events
Delayed Triggerable
After Events
Wait the
Wait
UserĆSpecified
Time
Delayed Triggerable
After Events/Time
UserĆSpecified
Number of
Delayed Trigger
Events
Figure 3Ć13:ăDelayed Triggerable
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Delayed Triggering
H
H
H
After Time waits the userĆspecified time, then waits for the next delayed
trigger event, and then acquires.
After Events waits for the specified number of delayed trigger events and
then acquires.
After Events/Time waits for the specified number of delayed trigger
events, then waits the userĆspecified time, and then acquires.
The digitizing oscilloscope is always acquiring samples to fill the pretrigger
part of the waveformrecord. When and if delay criteria are met, it takes
enough posttrigger samples to complete the delayed waveform record and
then displays it. Refer to Figure 3Ć14 for a more detailed look at how delayed
records are placed in time relative to the main trigger.
NOTE
When using the delayed triggerable mode, the digitizing oscilloĆ
scope provides a conventional edge trigger for the delayed time
base. The delayed time base will not trigger if the main trigger type
(as defined in the Main Trigger menu) is logic, if the main trigger
type is edge with its source set to auxiliary, or if the main trigger
type is pulse with the runt trigger class selected.
You use the Horizontal menu to select and define either delayed runs after
main or delayed triggerable. Delayed triggerable, however, requires further
selections in the Delayed Trigger menu.
Operation
Delayed Runs After Main
1. Press HORIZONTAL MENU ➞ Time Base (main) ➞ Delayed Only
(side) ➞ Delayed Runs After Main (side). Use the general purpose
knob or the keypad to set the delay time.
If you press Intensified (side), you display an intensified zone on the
main timebase record that shows where the delayed timebase record
occurs relative to the main trigger. For Delayed Runs After Main mode,
the start of the intensified zone corresponds to the start of the delayed
timebase record. The end of the zone corresponds to the end of the
delayed record.
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Delayed Triggering
Pretrigger Record
Posttrigger Record
Delayed Runs After Main
Delayed Trigger Waveform Record
Main Trigger Point
Main
Trigger
Source
Time Delay
Start Posttrigger Acquisition
(From Horiz Menu)
Delayed Triggerable By Events
Delayed Trigger Waveform Record
Main Trigger Point
Main
Trigger
Source
Delayed
Trigger
Source
Start Posttrigger Acquisition
(Trigger on nth Delayed
Trigger Event)
Waiting for nth Event
(Where n=5)
Delayed Triggerable By Time
Delayed Trigger Waveform Record
Main Trigger Point
Main
Trigger
Source
Delayed
Trigger
Source
Time Delay
(From Delay Trig Menu)
Start Posttrigger Acquisition
(First Trigger After Delay)
Delayed Triggerable By Events/Time
Delayed Trigger Waveform Record
Main Trigger Point
Main
Trigger
Source
Delayed
Trigger
Source
Start Posttrigger Acquisition
Time Delay
Waiting for nth Event
(Where n=4)
(From Delay Trig Menu)
Figure 3Ć14:ăHow the Delayed Triggers Work
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DelayedTriggering
DelayedTriggerable
You must makesurethat theMain Trigger menu settings arecompatible
with Delayed Triggerable.
1. Press TRIGGER MENU.
2. If Type is set to Logic, press Type (main) to change it to either Edge or
Pulse as fits your application. Logic typeis incompatiblewith Delayed
Triggerable.
3. If Source is set to Auxiliary, press Source (main). Select any source
other than Auxiliary from thesidemenu according to your application.
4. Press HORIZONTAL MENU ➞ Time Base (main) ➞ DelayedOnly
(side) ➞ DelayedTriggerable (side).
NOTE
The Delayed Triggerable menu item is not selectable unless incomĆ
patible Main Trigger menu settings are eliminated. (See the steps at
the beginning of this procedure.) If such is the case, the Delayed
Triggerable menu item is dimmer than other items in the menu.
By pressing Intensified (side), you can display an intensified zone that
shows where the delayed timebase record may occur (a valid delay
trigger event must be received) relative to the main trigger on the main
time base. For Delayed Triggerable After mode, the start of the intensiĆ
fied zonecorresponds to thepossiblestart point of thedelayed time
baserecord. Theend of thezonecontinues to theend of main time
base, since a delayed time base record may be triggered at any point
after the delay time elapses.
To learn how to define the intensity level of the normal and intensified
waveform, see Display Modes on page 3Ć26.
Now you need to bring up the Delayed Trigger menu so you can define
the delayed trigger event.
5. Press SHIFT DELAYED TRIG ➞ Delay by (main) ➞ Triggerable After
Time, Events, or Events/Time (side) (Figure 3Ć15).
6. Enter the delay time or events using the general purpose knob or the
keypad. If you selected Events/Time, use Time (side) and Events (side)
to switch between setting the time and the number of events.
Hint: You can go directly to the Delayed Trigger menu (see step 5). By
selecting one of Triggerable After Time, Events, or Events/Time, the
oscilloscope automatically switches to Delayed Triggerable in the HoriĆ
zontal menu. You will still need to display the Horizontal menu if you
wish to leave Delayed Triggerable.
The Source menu lets you select which input will be the delayed trigger
source.
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Delayed Triggering
7. Press Source (main) ➞ Ch1, Ch2, Ch3 (Ax1 on theTDS 620A), Ch4
(Ax2 on theTDS 620A), or Auxiliary (side).
Figure 3Ć15:ăDelayed Trigger Menu
8. Press Coupling (main) ➞ DC, AC, HF Rej, LF Rej, or Noise Rej (side)
to define how the input signal will be coupled to the delayed trigger. For
descriptions of these coupling types, see Triggering on page 2Ć13.
9. Press Slope (main) to select the slope that the delayed trigger will occur
on. Choose between the rising edge and falling edge slopes.
When using Delayed Triggerable mode to acquire waveforms, two
trigger bars are displayed. One trigger bar indicates the level set by the
main trigger system; the other indicates the level set by the delayed
trigger system.
10. Press Level (main) ➞ Level, Set to TTL, Set to ECL, or Set to 50%
(side).
H
Level lets you enter the delayed trigger level using the general
purposeknob or thekeypad.
H
H
Set to TTL fixes the trigger level at +1.4ĂV.
Set to ECL fixes the trigger level at -1.3ĂV.
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Delayed Triggering
NOTE
When you set the Vertical SCALE smaller than 200ĂmV, the oscilloĆ
scope reduces the Set to TTL or Set to ECL trigger levels below
standard TTL and ECL levels. That happens because the trigger
level range is fixed at ±12 divisions from the center. At 100ĂmV (the
next smaller setting after 200ĂmV) the trigger range is ±1.2ĂV which
is smaller than the typical TTL (+1.4ĂV) or ECL (-1.3ĂV) level.
H
Set to 50% fixes the delayed trigger level to 50% of the peakĆtoĆpeak
value of the delayed trigger source signal.
See Triggering, on page 2Ć13.
See Triggering, on page 3Ć132.
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Display Modes
The digitizing oscilloscope candisplay waveform records indifferent ways.
The Display menu lets you adjust the oscilloscope display style, intensity
level, graticule, and format.
To bring up the Display menu:
Operation
1. Press DISPLAY to show the Display menu.
2. Onthe TDS 644A, press Setting inthe mainmenu until you select
Display from the popĆup menu.
Display lets you adjust the style, intensity level, graticule, and format feaĆ
tures described below. Color (TDS 644A) lets you alter color settings for
various display components such as waveforms and text. For more informaĆ
tiononcolor, see Color onpage 3Ć10.
Display Style
Press DISPLAY ➞ Style (main) ➞ Vectors, Intensified Samples, Dots,
Infinite Persistence, or Variable Persistence (side) (Figure 3Ć16).
Figure 3Ć16:ăDisplay Menu Ċ Style
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Display Modes
H
H
H
Vectors has the display draw vectors (lines) between the record points.
Dots display waveform record points as dots.
Intensified Samples also displays waveform record points as dots.
However, the points actually sampled are displayed in the Zone color
(TDS 644A) or intensified relative to the interpolated points.
In addition to choosing Intensified Samples in the side menu, the oscilloĆ
scope must be interpolating or Zoom must be on with its horizontal expanĆ
sion greater that 1X. See interpolation on page 2Ć20; see Zoom beginning
on page 3Ć151.
H
Variable Persistence lets the record points accumulate on screen over
many acquisitions and remain displayed only for a specific time interval.
In that mode, the display behaves like that of an analog oscilloscope.
You enter the time for that option with the keypad or the general purĆ
pose knob. On color instruments, record points are also displayed with
colors that vary depending on the points persistence. See Choose
Palette on page 3Ć11.
H
Infinite Persistence lets the record points accumulate until you change
some control (such as scale factor) causing the display to be erased.
Intensity
Intensity lets you set text/graticule and waveform intensity (brightness)
levels. To set the intensity:
Press DISPLAY ➞ Intensity (main) ➞ Overall (TDS 640A & TDS 620A),
Text/Grat, Waveform, or Contrast (TDS 640A & TDS 620A) (side). Enter the
intensity percentage values with the keypad or the general purpose knob.
All intensity adjustments operate over a range from 20% (close to fully off) to
100% (fully bright).
Contrast (TDS 640A & TDS 620A) operates over a range from 100% (no
contrast) to 250% (intensified portion at full brightness).
NOTE
The Intensified setting for Timebase in the horizontal menu causes
a zone on the waveform to be displayed in the Zone color
(TDS 644A) or intensified relative to the rest of the waveform. If the
contrast is set to 100%, you won't be able to distinguish the intensiĆ
fied portion from the rest of the waveform because both are the
same brightness.
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Display Modes
Display Readout
Readout options controlwhether the trigger indicator, trigger el velbar, and
current date and time appear on the display. The options also control what
style trigger level bar, long or short, is displayed.
1. Press DISPLAY ➞ Readout (main).
2. Toggle Display `T' @ Trigger Point (side) to select whether or not to
display `T' indicating the trigger point. You can select ON or OFF. (The
trigger point indicates the position of the trigger in the waveform record.)
3. Press Trigger Bar Style (side) to select either the short or the long
trigger bar or to turn the trigger bar off. (See Figure 3Ć17. Note that both
styles are shown for illustrating purposes, but you can only display one
style at a time.)
The trigger bar is only displayed if the trigger source is an active, disĆ
played waveform. Also, two trigger bars are displayed when delay
triggerable acquisitions are displayed Ċ one for the main and one for
the delayed timebase. The trigger bar is a visual indicator of the trigger
level.
Sometimes, especially when using the hardcopy feature, you may wish
to display the current date and time on screen. For more information
about displaying and setting date and time, see Date/Time Stamping
Your Hardcopy on page 3Ć60.)
4. Press Display Date/Time (side) to turn it on or off. Push Clear Menu to
see the current date and time.
Trigger Point Indicator
Trigger BarĊLong Style
-or-
Trigger BarĊShort Style
Figure 3Ć17:ăTrigger Point and Level Indicators
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Display Modes
Filter Type
The display filter types are sin(x)/x interpolation and linear interpolation. For
more information see the Concepts section, page 2Ć20.
Press DISPLAY ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear InterpoĆ
lation (side).
NOTE
When the horizontal scale is set to rates faster than 25 ns/div, or
when using the ZOOM feature to expand waveforms horizontally,
interpolation occurs. (The filter type, linear or sin(x)/(x), depends on
which is set in the Display menu.) Otherwise, interpolation is not
needed. See Sampling and Digitizing on page 2Ć19 for a discusĆ
sion of sampling including interpolation.
Graticule Type
To change the graticule:
Press DISPLAY ➞ Graticule (main) ➞ Full, Grid, Cross Hair, Frame, NTSC
or PAL (side).
H
H
H
H
H
H
Full provides a grid, cross hairs and a frame.
Grid displays a frame and a grid.
Cross Hair provides cross hairs, and a frame.
Frame displays just a frame.
NTSC provides a grid usefulfor measuring NTSCĆcal ss waveforms.
PAL provides a grid usefulfor measuring PALĆcal ss waveforms.
NOTE
Selecting either NTSC or PAL graticules automatically changes the
vertical scale, position settings, coupling, and sets to zero any
vertical offset of any channel displayed. These settings are not
restored after switching to other graticule types. Therefore, you
might wish to recall the factory setup or other stored setup after
selecting a different graticule.
Format
There are two kinds of format: YT and XY.
YT is the conventional oscilloscope display format. It shows a signal voltage
(the verticalaxis) as it varies over time (the horizontalaxis).
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Display Modes
XY format compares the voltage levels of two waveform records point by
point. That is, the digitizing oscilloscope displays a graph ofthe voltage of
one waveform record against the voltage of another waveform record. This
mode is particularly useful for studying phase relationships.
To set the display axis format:
Press DISPLAY ➞ Format (main) ➞ XY or YT (side).
When you choose the XY mode, the input you have selected is assigned to
the XĆaxis, and the digitizing oscilloscope automatically chooses the YĆaxis
input (see Table 3Ć2).
TableĂ3Ć2:ăXY Format Pairs
XĆAxis Channel
(User Selectable)
YĆAxis Channel
(Fixed)
Ch 1
Ch 2
Ch 3 (TDS 644A & TDS 640A)
(Aux 1 on the TDS 620A)
Ch 4 (TDS 644A & TDS 640A)
(Aux 2 on the TDS 620A)
Ref1
Ref3
Ref2
Ref4
For example, ifyou press the CH 1 button, the digitizing oscilloscope will
display a graph ofthe channel 1 voltage levels on the XĆaxis against the
channel 2 voltage levels on the YĆaxis. That will occur whether or not you are
displaying the channel 2 waveform in YT format. If you later press the
WAVEFORM OFF button for either channel 1 or 2, the digitizing oscilloscope
will delete the XY graph ofchannel 1 versus channel 2.
Since selecting YT or XY affects only the display, the horizontal and vertical
scale and position knobs and menus control the same parameters regardĆ
less ofthe mode selected. Specifically, in XY mode, the horizontal scale will
continue to control the time base and the horizontal position will continue to
control which portion ofthe waveforms are displayed.
XY format is a dotĆonly display, although it can have persistence. The Vector
style selection has no effect when you select XY format.
You cannot display Math waveforms in XY format. They will disappear from
the display when you select XY.
NOTE
Use at higher room temperatures or with higher intensity display
formats, such as the white fields in the Hardcopy palette, can
temporarily degrade display quality.
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DisplayModes
See Acquisition, on page 2Ć19.
See Color, on page 3Ć10.
For More
Information
See Measurements, on page 2Ć26.
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Edge Triggering
An edge trigger event occurs when the trigger source passes through a
specified voltage level in a specified direction (the trigger slope). You will
likely use edge triggering for most of your measurements.
You can select the edge source, coupling, slope, level, and mode (auto or
normal).
The Trigger readout shows some key trigger parameters (Figure 3Ć18).
Edge Trigger
Readouts
Main Time Base Time/Div
Main Time Base
Main Trigger
Source = Ch 1
Main Trigger
Slope = Rising Edge
Main Trigger
Level
Figure 3Ć18:ăEdge Trigger Readouts
The Edge Trigger menu lets you select the source, coupling, slope, trigger
level, mode, and holdoff.
Operation
To bring up the Edge Trigger menu:
Press TRIGGER MENU ➞ Type (main) ➞ Edge (popĆup) (see Figure 3Ć19).
Source
To select which source you want for the trigger:
Press TRIGGER MENU ➞ Type (main) ➞ Edge (popĆup) ➞
Source (main) ➞ Ch1, Ch2, Ch3 (Ax1 on the TDS 620A), Ch4 (Ax2 on the
TDS 620A), AC Line, or Auxiliary (side).
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Edge Triggering
Figure 3Ć19:ăMain Trigger Menu Ċ Edge Type
Coupling
To select the coupling you want:
Press TRIGGER MENU ➞ Type (main) ➞ Edge (popĆup) ➞ CouĆ
pling (main) ➞ DC, AC, HF Rej, LF Rej, or Noise Rej (side).
H
H
H
DC passes all of the input signal. In other words, it passes both AC and
DC components to the trigger circuit.
AC passes only the alternating components of an input signal (above
10 Hz). It removes the DC component from the trigger signal.
HF Rej removes the high frequency portion of the triggering signal. That
allows only the low frequency components to pass on to the triggering
system to start an acquisition. High frequency rejection attenuates
signals above 30 kHz.
H
H
LF Rej does the opposite of high frequency rejection. Low frequency
rejection attenuates signals below 80 kHz.
Noise Rej provides lower sensitivity. Noise Rej requires additional
signal amplitude for stable triggering, reducing the chance of falsely
triggering on noise.
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Edge Triggering
Slope
To select the slope that the edge trigger will occur on:
1. Press the TRIGGER MENU ➞ Type (main) ➞ Edge (popĆup) ➞
Slope (main).
2. Alternatives for slope are the rising and falling edges.
Level
Press the TRIGGER MENU ➞ Type (main) ➞ Edge (popĆup) ➞
Level (main) ➞ Level, Set to TTL, Set to ECL, or Set to 50% (side).
H
Level lets you enter the trigger level using the general purpose knob or
the keypad.
H
H
Set to TTL fixes the trigger level at +1.4ĂV.
Set to ECL fixes the trigger level at -1.3ĂV.
NOTE
Whenyou set the volts/div smaller than200ĂmV, the oscilloscope
reduces the Set to TTL or Set to ECL trigger levels below standard
TTL and ECL levels. That happens because the trigger level range
is fixed at ±12 divisions from the center. At 100ĂmV (the next smallĆ
er setting after 200ĂmV) the trigger range is ±1.2ĂV, which is smaller
thanthe typical TTL (+1.4ĂV) or ECL (-1.3ĂV) level.
H
Set to 50% fixes the trigger level to approximately 50% of the peakĆtoĆ
peak value of the trigger source signal.
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Edge Triggering
Mode & Holdoff
You can change the holdoff time and select the trigger mode using this
menu item. See Triggering on page 2Ć13 for more details.
1. Press the TRIGGER MENU ➞ Mode & Holdoff (main) ➞ Auto or NorĆ
mal (side).
H
H
In Auto mode the oscilloscope acquires a waveform after a specific
time has elapsed even if a trigger does not occur. The amount of
time the oscilloscope waits depends on the time base setting.
In Normal mode the oscilloscope acquires a waveform only if there
is a valid trigger.
2. To change the holdoff time, press Holdoff (side). Enter the value in %
using the general purpose knob or the keypad.
If you want to enter a large number using the general purpose knob, press
the SHIFT button before turning the knob. When the light above the SHIFT
button is on and the display says Coarse Knobs in the upper right corner,
the general purpose knob speeds up significantly.
You can set holdoff from 0% (minimum holdoff available) to 100% (maximum
available). See Holdoff, Variable, Main Trigger in the TDS 620A, 640A, &
644A Performance Verification Manual, Section 2 on Specifications, Typical
Characteristics for typical minimum and maximum values.
Holdoff is automatically reset to 0% when you change the main time base
time/division setting. However, it is not reset if you change the delayed time
base time/division (that is, when the time base setting in the Horizontal
menu is Intensified or Delayed Only).
See Triggering, on page 2Ć13.
For More
Information
See Triggering, on page 3Ć132.
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Fast Fourier Transforms
Advanced DSP Math (optional on TDS 620A & TDS 640A), provides the Fast
Fourier Transform (FFT). The FFT allows you to transform a waveform from a
display of its amplitude against time to one that plots the amplitudes of the
various discrete frequencies the waveform contains. Further, you can also
display the phase shifts of those frequencies. Use FFT math waveforms in
the following applications:
H
H
H
H
H
H
Testing impulse response of filters and systems
Measuring harmonic content and distortion in systems
Characterizing the frequency content of DC power supplies
Analyzing vibration
Analyzing harmonics in 50 and 60 cycle lines
Identifying noise sources in digital logic circuits
The FFT computes and displays the frequency content of a waveform you
acquire as an FFT math waveform. This frequency domain waveform is
based on the following equation:
Description
N
* 1
2
j2pnk
N
*
Ă
ĂĂĂĂĂĂ
1
N
X(k) +
x(n)e
for : k + 0Ă toĂ N * 1
Ă
SĂ
2
* N
n +
Where:
x(n) is a point in the time domain record data array
X(k) is a point in the frequency domain record data array
n is the index to the time domain data array
k is the index to the frequency domain data array
N is the FFT length
j is the square root of −1
The resulting waveform is a display of the magnitude or phase angle of the
various frequencies the waveform contains with respect to those frequenĆ
cies. For example, Figure 3Ć20 shows the nonĆtransformed impulse reĆ
sponse of a system in channel 2 at the top of the screen. The FFTĆtransĆ
formed magnitude and phase appear in the two math waveforms below the
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Fast Fourier Transforms
impulse. The horizontal scale for FFT math waveforms is always expressed
in frequency per division with the beginning (leftĆmost point) of the waveform
representing zero frequency (DC).
The FFT waveform is based on digital signal processing (DSP) of data,
which allows more versatility in measuring the frequency content of waveĆ
forms. For example, DSP allows the oscilloscope to compute FFTs of source
waveforms that must be acquired based on a single trigger, making it useful
for measuring the frequency content of single events.
Normal Waveform of an
Impulse Response
FFT Waveform of the
Magnitude Response
FFT Waveform of the
Phase Response
Figure 3Ć20:ăSystem Response to an Impulse
To obtainanFFT of your waveform:
Operation
1. Connect the waveform to the desired channel input and select that
channel.
2. Adjust the vertical and horizontal scales and trigger the display (or press
AUTOSET).
The topic Offset, Position, and Scale, onpage 3Ć44, provides indepth
information about optimizing your setup for FFT displays.
3. Press MORE to access the menu for turning on math waveforms.
4. Select a math waveform. Your choices are Math1, Math2, an d
Math3 (main).
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Fast Fourier Transforms
Figure 3Ć21:ăDefine FFT Waveform Menu
5. If the selected math waveform is not FFT, press Change Math DefiniĆ
tion (side) ➞ FFT (main). See Figure 3Ć21.
6. Press Set FFT Source to (side) repeatedly until the channel source
selected in step 1 appears in the menu label.
7. Press Set FFT Vert Scale to (side) repeatedly to choose from the followĆ
ing vertical scale types:
H
dBV RMS Ċ Magnitude is displayed using log scale, expressed in
dB relative to 1 V where 0 dB =1 V
.
RMS
RMS
H
H
Linear RMS Ċ Magnitude is displayed using voltage as the scale.
Phase (deg) Ċ Phase is displayed using degrees as the scale,
where degrees wrap from -180_ to +180_.
Phase (rad) Ċ Phase is displayed using radians as the scale,
H
where radians wrap from -p to +p.
The topic Considerations for Phase Displays, on page 3Ć47, provides in
depth information on setup for phase displays.
8. Press Set FFT Window to (side) repeatedly to choose from the following
window types:
H
Rectangular Ċ Best type for resolving frequencies that are very
close to the same value but worst for accurately measuring the
amplitude of those frequencies. Best type for measuring the freĆ
quency spectrum of nonĆrepetitive signals and measuring frequency
components near DC.
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Fast Fourier Transforms
H
Hamming Ċ Very good window for resolving frequencies that are
very close to the same value with somewhat improved amplitude
accuracy over the rectangular window.
H
H
Hanning Ċ Very good window for measuring amplitude accuracy
but degraded for resolving frequencies.
BlackmanĆHarris Ċ Best window for measuring the amplitude of
frequencies but worst at resolving frequencies.
The topic Selecting the Window, on page 3Ć49, provides in depth inĆ
formation on choosing the right window for your application.
9. If you did not select Phase(deg) or Phase(rad) in step 7, skip to
step 12. Phase suppression is only used to reduce noise in phase FFTs.
10. If you need to reduce the effect of noise in your phase FFT, press SupĆ
press phase at amplitudes < (side).
11. Use the general purpose knob (or the keypad if your oscilloscope is so
equipped) to adjust the phase suppression level. FFT magnitudes below
this level will have their phase set to zero.
The topic Adjust Phase Suppression, on page 3Ć48, provides additional
information on phase suppression.
12. Press OK Create Math Wfm (side) to display the FFT of the waveform
you input in step 1 (see Figure 3Ć22).
Figure3Ć22:ăFFT Math Waveform in Math1
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Fast Fourier Transforms
Cursor Measurements of an FFT
Once you have displayed an FFT math waveform, use cursors to measure
its frequency amplitude or phase angle.
1. Be sure MORE is selectedin the channel selection buttons andthat the
FFT math waveform is selectedin the More main menu.
2. Press CURSOR ➞ Mode (main) ➞ Independent (side) ➞ FuncĆ
tion (main) ➞ H Bars (side).
3. Use the general purpose knob to align the selectedcursor (solidline) to
the top (or to any amplitude on the waveform you choose).
4. Press SELECT to select the other cursor. Use the general purpose knob
to align the selectedcursor to the bottom (or to any amplitude on the
waveform you choose).
5. Readthe amplitude between the two cursors from the D: readout. Read
the amplitude of the selected cursor relative to either 1 V
(0 dB),
RMS
ground (0 volts), or the zero phase level (0 degrees or 0 radians) from
the @: readout. (The waveform reference indicator at the left side of the
graticule indicates the level where phase is zero for phase FFTs.)
Figure 3Ć23 shows the cursor measurement of a frequency magnitude
on an FFT. The @: readout reads 0 dB because it is aligned with the
1 V
level. The D: readout reads 24.4 dB indicating the magnitude of
RMS
the frequency it is measuring is -24.4 dB relative to 1 V
waveform is turnedoff in the display.
. The source
RMS
The cursor units will be in dB or volts for FFTs measuring magnitude and
in degrees or radians for those FFTs measuring phase. The cursor unit
depends on the selection made for Set FFT Vert Scale to (side). See
step 7 on page 3Ć38 for more information.
6. Press V Bars (side). Use the general purpose knob to align one of the
two vertical cursors to a point of interest along the horizontal axis of the
waveform.
7. Press SELECT to select the alternate cursor.
8. Align the selectedcursor to another point of interest on the math waveĆ
form.
9. Readthe frequency difference between the cursors from the D: readout.
Readthe frequency of the selectedcursor relative to the zero frequency
point from the @: readout.
The cursor units will always be in Hz, regardless of the setting in the
Time Units side menu. The first point of the FFT record is the zero
frequency point for the @: readout.
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Fast Fourier Transforms
Figure 3Ć23:ăCursor Measurement of an FFT Waveform
10. Press Function (main) ➞ Paired (side).
11. Use the technique just outlined to place the vertical bar of each paired
cursor to the points along the horizontal axis you are interested in.
12. Read the amplitude between the X of the two paired cursors from the
topĆmost D: readout. Read the amplitude of the short horizontal bar of
the selected (solid) cursor relative to either 1 V
(0 dB), ground
RMS
(0 volts), or zero phase level (0 degrees or 0 radians) from the @: readĆ
out. Read the frequency between the long horizontal bars of both paired
cursors from the bottom D: readout.
Automated Measurements of an FFT
You can also use automated measurements to measure FFT math waveĆ
forms. Use the same procedure as is found under Waveform Differentiation
on page 3Ć140.
There are severalcharacteristics of FFTs that affect how they are dispal yed
and should be interpreted. Read the following topics to learn how to optiĆ
mize the oscilloscope setup for good display of your FFT waveforms.
Considerations for
Using FFTs
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Fast Fourier Transforms
The FFT Frequency Domain Record
The following topics discuss the relation of the source waveform to the
record length, frequency resolution, and frequency range of the FFT freĆ
quency domain record. (The FFT frequency domain waveform is the FFT
math waveform that you display.)
FFTs May Not Use All of the Waveform Record Ċ The FFT math
waveform is a display of the magnitude or phase data from the FFT frequenĆ
cy domain record. This frequency domain record is derived from the FFT
time domain record, which is derived from the waveform record. All three
records are described below.
Waveform Record Ċ the complete waveform record acquired from an input
channel and displayed from the same channel or a reference memory. The
length of this time domain record is userĆspecified from the Horizontal menu.
The waveform record is not a DSP Math waveform.
FFT Time Domain Record Ċ that part of the waveform record that is input to
the FFT. This time domain record waveform becomes the FFT math waveĆ
form after it is transformed. Its record length depends on the length of the
waveform record defined above.
FFT Frequency Domain Record Ċ the FFT math waveform after digital signal
processing converts data from the FFT time domain record into a frequency
domain record.
Figure 3Ć24 compares the waveform record to the FFT time domain record.
Note the following relationships:
H
H
H
H
For waveform records ≤10 K points in length, the FFT uses all of the
waveform record as input.
For waveform records >10 K points, the first 10 K points of the waveform
record becomes the FFT time domain record.
Each FFT time domain record starts at the beginning of the acquired
waveform record.
The zero phase reference point for a phase FFT math waveform is in the
middle of the FFT time domain record regardless of the waveform record
length.
Reference
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Fast Fourier Transforms
FFT Time Domain Record =
Waveform Record
Waveform Record ≤ 10 K
Zero Phase
Reference
FFT Time Domain Record = 10k
Waveform Record > 10 K
Zero Phase
Reference
Figure 3Ć24:ăWaveform Record vs. FFT Time Domain Record
FFTs Transform Time Records to Frequency Records Ċ The FFT
time domain record just described is input for the FFT. Figure 3Ć25 shows
the transformation of that time domain data record into an FFT frequency
domain record. The resulting frequency domain record is one half the length
of the FFT input because the FFT computes both positive and negative
frequencies. Since the negative values mirror the positive values, only the
positive values are displayed.
FFT Time Domain Record
FFT
FFT Frequency Domain Record
Figure 3Ć25:ăFFT Time Domain Record vs. FFT Frequency Domain
Record
FFT Frequency Range and Resolution Ċ When you turn on an FFT
waveform, the oscilloscope displays either the magnitude or phase angle of
the FFT frequency domain record. The resolution between the discrete
frequencies displayed in this waveform is determined by the following equaĆ
tion:
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Fast Fourier Transforms
SampleĂ Rate
FFTĂ Length
DF +
Where:
DF is the frequency resolution.
Sample Rate is the sample rate of the source waveform.
FFT Length is the length of the FFT Time Domain waveform
record.
The sample rate also determines the range these frequencies span; they
span from 0 to ½ the sample rate of the waveform record. (The value of ½
the sample rate is often referred to as the Nyquist frequency or point.) For
example, a sample rate of20 Megasamples per second would yield an FFT
with a range of0 to 10 MHz. The sample rates available of r acquiring data
records vary over a range the limits ofwhich depend on your oscilloscope
model. TDS oscilloscopes display the sample rate in the acquisition readout
at the top ofthe oscilloscope screen.
Offset, Position, and Scale
The following topics contain information to help you display your FFT propĆ
erly.
Adjust for a NonĆClipped Display Ċ To properly display your FFT waveĆ
form, scale the source waveform so it is not clipped.
H
You should scale and position the source waveform so it is contained on
screen. (Off screen waveforms may be clipped, resulting in errors in the
FFT waveform).
Alternately, to get maximum vertical resolution, you can display source
waveforms with amplitudes up to two divisions greater than that of the
screen. Ifyou do, turn on PkĆPk in the measurement menu and monitor
the source waveform for clipping.
H
Use vertical position and vertical offset to position your source waveĆ
form. As long as the source waveform is not clipped, its vertical position
and vertical offset will not affect your FFT waveform except at DC. (DC
correction is discussed below.)
Adjust Offset and Position to Zero for DC Correction Ċ Normally, the
output ofa standard FFT computation yields a DC value that is twice as
large as it should be with respect to the other frequencies. Also, the selecĆ
tion ofwindow type introduces errors in the DC value ofan FFT.
The displayed output ofthe FFT on TDS oscilloscopes is corrected of r these
errors to show the true value for the DC component of the input signal. The
Position and Offset must be set to zero for the source waveform in the
Vertical menu. When measuring the amplitude at DC, remember that 1 VDC
equals 1 V
and the display is in dB.
RMS
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Fast Fourier Transforms
Record Length
Most often, you will want to use a short record length because more of the
FFT waveform can be seen on screen and long record lengths can slow
oscilloscope response. However, long record lengths lower the noise relative
to thesignal and increasethefrequency resolution for theFFT. MoreimporĆ
tant, they might be needed to capture the waveform feature you want to
includein theFFT.
To speed up oscilloscope response when using long record lengths, you
can save your source waveform in a reference memory and perform an FFT
on thesaved waveform. That way theDSP will computetheFFT based on
saved, static data and will only update if you save a new waveform.
Acquisition Mode
Selecting theright acquisition modecan produceless noisy FFTs.
Set up in Sample or Normal Mode Ċ Usesamplemodeuntil you haveset
up and turned on your FFT. Samplemodecan acquirerepetitiveand nonreĆ
petitive waveforms and does not affect the frequency response of the source
waveform.
Hi Res and Average Reduce Noise Ċ After the FFT is set up and disĆ
played, it might be useful to turn on Hi Res mode, on TDS models so
equipped, to reduce the effect of noise in the signal. Hi Res operates on
both repetitive and nonrepetitive waveforms; however, it does affect the
frequency response of the source waveform.
If the pulse is repetitive, Average mode may be used to reduce noise in the
signal at a cost of slower display response. Average operates on repetitive
waveforms only, and averaging does affect the frequency response of the
sourcewaveform.
Peak Detect (on TDS models so equipped) and Envelope mode can add
significant distortion to the FFT results and are not recommended for use
with FFTs.
Zoom and Interpolation
Once you have your waveform displayed optimally, you may magnify (or
reduce) it vertically and horizontally to inspect any feature you desire. Just
be sure the FFT waveform is the selected waveform. (Press MORE, then
select the FFT waveform in the More main menu. Then use the Vertical and
Horizontal SCALE knobs to adjust the math waveform size.)
If you wish to see the zoom factor (2X, 5X, etc.) you need to turn Zoom on:
press ZOOM ➞ On (side). The vertical and horizontal zoom factors appear
on screen.
Whether Zoom is on or off, you can press Reset Zoom Factors (side) to
return the zoomed FFT waveform to no magnification.
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Fast Fourier Transforms
Zoom always uses either sin(x)/x or linear interpolation when expanding
displayed waveforms. To select the interpolation method: press DISPLAY ➞
Setting (main) ➞ Display (popĆup) ➞ Filter (main) ➞ Sin(x)/x or Linear
(side), or ifyour oscilloscope does not have color, press DISPLAY ➞ FilĆ
ter (main)➞ Sin(x)/x or Linear (side)
Ifthe source waveform record length is 500 points, the FFT will use 2X Zoom
to increase the 250 point FFT frequency domain record to 500 points. ThereĆ
fore, FFT math waveforms of 500 point waveforms are always zoomed 2X or
more with interpolation. Waveforms with other record lengths can be
zoomed or not and can have minimum Zooms of1X or less.
Sin(x)/x interpolation may distort the magnitude and phase displays ofthe
FFT depending on which window was used. You can easily check the efĆ
fects of the interpolation by switching between sin(x)/x and linear interpolaĆ
tion and observing the difference in measurement results on the display. If
significant differences occur, use linear interpolation.
Undersampling (Aliasing)
Aliasing occurs when the oscilloscope acquires a source waveform with
frequency components outside of the frequency range for the current samĆ
ple rate. In the FFT waveform, the actual higher frequency components are
undersampled, and therefore, they appear as lower frequency aliases that
fold back" around the Nyquist point (see Figure 3Ć26).
The greatest frequency that can be input into any sampler without aliasing is
½ the sample frequency. Since source waveforms often have a fundamental
frequency that does not alias but have harmonic frequencies that do, you
should have methods for recognizing and dealing with aliases:
H
Be aware that a source waveform with fast edge transition times creates
many high frequency harmonics. These harmonics typically decrease in
amplitude as their frequency increases.
H
H
H
Sample the source signal at rates that are at least 2X that ofthe highest
frequency component having significant amplitude.
Filter the input to bandwidth limit it to frequencies below that of the
Nyquist frequency.
Recognize and ignore the aliased frequencies.
Ifyou think you have aliased rfequencies in your FFT, select the source
channel and adjust the horizontal scale to increase the sample rate. Since
you increase the Nyquist frequency as you increase the sample rate, the
alias signals should appear at their proper frequency.
Reference
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Fast Fourier Transforms
Nyquist Frequency
Point
Frequency
Aliased Frequencies
Actual Frequencies
Figure 3Ć26:ăHow Aliased Frequencies Appear in an FFT
Considerations for Phase Displays
When you set up an FFT math waveform to display the phase angle of the
frequencies contained in a waveform, you should take into account the
reference point the phase is measured against. You may also need to use
phase suppression to reduce noise in your FFTs.
Establish a Zero Phase Reference Point Ċ The phase of each freĆ
quency is measured with respect to the zero phase reference point. The
zero reference point is the point at the center of the FFT math waveform but
corresponds to various points on the source (time domain) record. (See
Figure 3Ć24 on page 3Ć43.)
To measure the phase relative to most source waveforms, you need only to
center the positive peak around the zero phase point. (For instance, center
the positive half cycle for a sine or square wave around the zero phase
point.) Use the following method:
H
First be sure the FFT math waveform is selected in the More menu, then
set horizontal position to 50% in the Horizontal menu. This positions the
zero phase reference point to the horizontal center of the screen.
H
In the Horizontal menu, vary the trigger position to center the positive
peak of the source waveform at the horizontal center of screen. AlterĆ
nately, you can adjust the trigger level (knob) to bring the positive peak
to center screen if the phase reference waveform has slow enough
edges.
When impulse testing and measuring phase, align the impulse input into the
system to the zero reference point of the FFT time domain waveform:
H
Set the trigger position to 50% and horizontal position to 50% for all
record lengths less than 15 K. (Your model oscilloscope may not have
record lengths of 15 K or longer Ċ consult your User manual.)
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Fast Fourier Transforms
H
H
For records with a15 K length, set the trigger position to 33%. Use the
horizontal position knob to move the trigger T on screen to the center
horizontal graticule line.
For records with 30 K, 50 K, or 60 K lengths (not all lengths are available
for all TDS models Ċ consult your User manual), set the trigger position
to 16.6%,10%, or 8.3%, respectively. Use the horizontal position knob to
move the trigger T on screen and to the center horizontal graticule line.
H
Trigger on the input impulse.
Adjust Phase Suppression Ċ Your source waveform record may have a
noise component with phase angles that randomly vary from −pi to pi. This
noise could make the phase display unusable. In such a case, use phase
suppression to control the noise.
You specify the phase suppression level in dB with respect to 1 V
. If the
RMS
magnitude of the frequency is greater than this threshold, then its phase
angle will be displayed. However, if it is less than this threshold, then the
phase angle will be set to zero and be displayed as zero degrees or radians.
(The waveform reference indicator at the left side of the graticule indicates
the level where phase is zero for phase FFTs.)
It is easier to determine the level of phase suppression you need if you first
create a frequency FFT math waveform of the source and then create a
phase FFT waveform of the same source. Do the following steps to use a
cursor measurement to determine the suppression level:
1. Do steps 1 through 7 of Operation that begins on page 3Ć37. Select dBV
RMS (side) for the Set FFT Vert Scale to (side).
2. Press CURSOR ➞ Mode (main) ➞ Independent (side) ➞ FuncĆ
tion (main) ➞ H Bars (side). Use the general purpose knob to align the
selected cursor to a level that places the tops of the magnitudes of
frequencies of interest above the cursor but places other magnitudes
completely below the cursor.
3. Read the level in dB from the @: readout. Note the level for use in
step 5.
4. Press MORE (main) ➞ Change Waveform Definition menu (side).
Press Set FFT Vert Scale to (side) repeatedly to choose either Phase
(rad) or Phase (deg).
5. Press Suppress Phase at Amplitudes (side). Use the general purpose
knob (or keypad if your oscilloscope is so equipped) to set phase supĆ
pression to the value obtained using the H Bar cursor. Do not change
the window selection or you will invalidate the results obtained using the
cursor.
Reference
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FastFourier Transforms
FFT Windows
To learnhow to optimize your display of FFT data, read about how the FFT
windows data before computing the FFT math waveform. Understanding
FFT windowing can help you get more useful displays.
Windowing Process Ċ The oscilloscope multiplies the FFT time domain
record by one of four FFT windows before it inputs the record to the FFT
function. Figure 3Ć27 shows how the time domain record is processed.
The FFT windowing acts like a bandpass filter between the FFT time domain
record and the FFT frequency domain record. The shape of the window
controls the ability of the FFT to resolve (separate) the frequencies and to
accurately measure the amplitude of those frequencies.
Selecting a Window Ċ You canselect your window to provide better
frequency resolution at the expense of better amplitude measurement
accuracy in your FFT, better amplitude accuracy over frequency resolution,
or to provide a compromise betweenboth. You canchoose from these four
windows: Rectangular, Hamming, Hanning, and BlackmanĆHarris.
Instep 8 (page 3Ć38) in Displaying an FFT, the four windows are listed in
order according to their ability to resolve frequencies versus their ability to
accurately measure the amplitude of those frequencies. The list indicates
that the ability of a given window to resolve a frequency is inversely proporĆ
tional to its ability to accurately measure the amplitude of that frequency. In
general, then, choose a window that can just resolve between the frequenĆ
cies you want to measure. That way, you will have the best amplitude accuĆ
racy and leakage elimination while still separating the frequencies.
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Fast Fourier Transforms
FFT Time Domain Record
Xs
FFT Window
FFT Time Domain Record
After Windowing
FFT
FFT Frequency Domain Record
Figure 3Ć27:ăWindowing the FFT Time Domain Record
Youcan often determine the best window empirically by first using the
window with the most frequency resolution (rectangular), then proceeding
toward that window with the least (BlackmanĆHarris) until the frequencies
merge. Use the window just before the window that lets the frequencies
merge for best compromise between resolution and amplitude accuracy.
NOTE
If the Hanning window merges the frequencies, try the Hamming
window before settling on the rectangular window. Depending on
the distance of the frequencies you are trying to measure from the
fundamental, the Hamming window sometimes resolves frequenĆ
cies better than the Hanning.
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Fast Fourier Transforms
Window Characteristics Ċ When evaluating a window for use, you may
want to examine how it modifies the FFT time domain data. Figure 3Ć28
shows each window, its bandpass characteristic, bandwidth, and highest
side lobe. Consider the following characteristics:
H
H
The narrower the centralol be for a given window, the better it can
resolve a frequency.
The lower the lobes on the side of each central lobe are, the better the
amplitude accuracy of the frequency measured in the FFT using that
window.
H
Narrow lobes increase frequency resolution because they are more
selective. Lower side lobe amplitudes increases accuracy because they
reduce leakage.
Leakage results when the FFT time domain waveform delivered to the
FFT function contains a nonĆinteger number of waveform cycles. Since
there are fractions of cycles in such records, there are discontinuities at
the ends of the record. These discontinuities cause energy from each
discrete frequency to leak" over on to adjacent frequencies. The result
is amplitude error when measuring those frequencies.
The rectangular window does not modify the waveform record points; it
generally gives the best frequency resolution because it results in the most
narrow lobe width in the FFT output record. If the time domain records you
measured always had an integer number of cycles, you would only need
this window.
Hamming, Hanning, and BlackmanĆHarris are all somewhat bellĆshaped
widows that taper the waveform record at the record ends. The Hanning and
Blackman/Harris windows taper the data at the end of the record to zero;
therefore, they are generally better choices to eliminate leakage.
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Fast Fourier Transforms
FFT Window Type
Bandpass Filter
Ć3 dB Bandwidth
Highest Side Lobe
0 dB
-20
0.89
Ć13 dB
-40
-50
Rectangular Window
0 dB
-20
-40
1.28
1.28
1.28
-43 dB
-32 dB
-94 dB
Hamming Window
-60
0 dB
-20
-40
-60
-80
Hanning Window
0 dB
-20
-40
-60
-80
BlackmanĆHarris
Window
-100
-101
Figure 3Ć28:ăFFT Windows and Bandpass Characteristics
Care should be takenwhenusing bell shaped widows to be sure that the
most interesting parts of the signal in the time domain record are positioned
in the center region of the window so that the tapering does not cause
severe errors.
See Waveform Differentiation, onpage 3Ć139.
See Waveform Integration, onpage 3Ć143.
See Waveform Math, onpage 3Ć148.
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File System (Optional on TDS 620A &
TDS 640A)
The File Utilities menu, which comes with the Hardcopy, Save Setup, and
Save Waveforms menus, gives you a variety of features for managing the
floppy disk.
The File Utilities menu lets you delete, rename, copy, print files, create a new
directory, operate the confirm delete and overwrite lock, and format disks.
Operation
To bring up the File Utilities menu:
1. Press the SETUP button to bring up the Save/Recall Setup menu, or
press the WAVEFORM buttonto bring up the Save/Recall Waveform
menu, or press the Shift HARDCOPY buttonto bring up the Hardcopy
menu.
2. Press File Utilities inthe mainmenu to bring up the File Utilities side
menu. (see Figure 3Ć29).
Figure 3Ć29:ăFile Utilities
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File System
NOTE
The amount of free space onthe disk is showninthe upper right
corner of the display. The digitizing oscilloscope shows the amount
in K bytes. To convert the amount to bytes, you simply multiply the K
bytes amount times 1024. Thus, the 711 kB showninFigure 3Ć29 =
711 Kbytes * 1024 bytes/K = 728,064 bytes.
Delete
To delete a file or directory, turn the general purpose knob until it scrolls the
cursor over the name of the file or directory to delete. Then, press the side
menu Delete button.
To delete all files in the file list, set the cursor to the *.* selection.
The digitizing oscilloscope deletes directories recursively. That means it
deletes both the directories and all their contents.
Rename
To rename a file or directory, turn the general purpose knob until it scrolls
the cursor over the name of the file or directory to delete. For example, to
rename the target file whose default name is TEK????? set the cursor over
its name. Then, press the side menu Rename button.
The labelling menu should appear. Turn the general purpose knob or use
the mainĆmenuarrow keys to select each letter. Press Enter Char from the
main menuto enter each letter. When youhave entered the name, press the
side menu OK Accept item (See Figure 3Ć30).
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File System
Figure 3Ć30:ăFile System Ċ Labelling Menu
Copy
To copy a file or directory, turn the general purpose knob until it scrolls the
cursor over the name of the file to copy. Then, press the side menu Copy
button. The file menu will reappear with the names of directories to copy to.
Select a directory and press the sideĆmenu button labelled Copy <name>
to Selected Directory.
To copy all files, select the *.* entry.
The digitizing oscilloscope copies all directories recursively. That means it
copies both the directories and all their contents.
Print
To print a file, turn the general purpose knob until it scrolls the cursor over
the name of the file to print. Then, press the sideĆmenu Print button.
The PrintĆTo side menu should appear. Select the port to print to from GPIB,
RSĆ232, or Centronics. (See Figure 3Ć30) Then the digitizing oscilloscope
will send the file in its raw form out the port. The device (printer) receiving
the file must be capable or printing the particular file format.
Create Directory
To create a new directory, press the side menu Create Directory button.
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File System
The labelling menu should appear. Turn the general purpose knob or use
the mainĆmenu arrow keys to select each letter. Press Enter Char from the
main menu to enter each letter. When you have entered the name, press the
side menu OK Accept item. (See Figure 3Ć30)
Confirm Delete
To turn on or off the confirm delete message, toggle the side menu Confirm
Delete button.
When the confirm delete option is OFF, the digitizing oscilloscope can imĆ
mediately delete files or directories. When the confirm option is ON, the
digitizing oscilloscope warns you before it deletes files and gives you a
chance to reconsider
Overwrite Lock
To turn on or off the file overwrite lock, toggle the side menu Overwrite Lock
button.
When overwrite lock is on, the digitizing oscilloscope will not permit you to
write over an existing file of the same name. An important reason to allow
overwriting is to let you write files using a target file name that contains wild
card characters (?"). This means the digitizing oscilloscope creates seĆ
quential files whose names are similar except for the sequential numbers
that go in the real name in the place of the question marks.
Format
To format a 720 Kbyte or 1.44 Mbyte disk, turn the general purpose knob
until it scrolls the cursor over the name of the drive to format in. (fd0:) Then,
press the side menu Format button.
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Hardcopy
You can get a copy of the digitizing oscilloscope display by using the hardĆ
copy feature. Depending on the output format you select, you create either
an image or a plot. Images are direct bit map representations of the digitizĆ
ing oscilloscope display. Plots are vector (plotted) representations of the
display.
Different hardcopy devices use different formats. The digitizing oscilloscope
supports the following formats:
HardcopyFormats
H
H
H
H
H
H
H
H
H
H
H
H
HP Thinkjet inkjet printer
HP Deskjet inkjet printer
HP Laserjet laser printer
Epson
DPUĆ411/II portable thermal printer
DPUĆ412 portable thermal printer
PCX (PC Paintbrush)
PCX Color (PC Paintbrush) (TDS 644A)
TIFF (Tag Image File Format)
BMP Mono (Microsoft Windows file format)
BMP Color (Microsoft Windows file format) (TDS 644A)
RLE Color (Microsoft Windows color image file format - compressed)
(TDS 644A)
H
H
H
H
H
H
EPS Mono Image (Encapsulated Postscript, monoĆimage)
EPS Color Image (Encapsulated Postscript, colorĆimage) (TDS 644A)
EPS Mono Plot (Encapsulated Postscript, monoĆplot)
EPS Color Plot (Encapsulated Postscript, colorĆplot)
Interleaf
HPGL Color Plot
Some formats, particularly Interleaf, EPS, TIFF, PCX, BMP, and HPGL, are
compatible with various desktop publishing packages. That means you can
paste files created from the oscilloscope directly into a document on any of
those desktop publishing systems.
EPS Mono and Color formats are compatible with Tektronix Phaser Color
Printers, HPGL is compatible with the Tektronix HC100 Plotter, and Epson is
compatible with the Tektronix HC220 Printer.
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Hardcopy
Before you make a hardcopy, you need to set up communications and
hardcopy parameters. This discussion assumes that the hardcopy device is
already connected to the GPIB port on the rear panel. If that is not the case
see Connection Strategies on page 3Ć61.
Operation
Setting Communication Parameters
To set up the communication parameters to talk to a printer attached directly
to the oscilloscope GPIB port:
Press SHIFT UTILITY ➞ System (main) ➞ I/O (popĆup) ➞ Port ➞
GPIB (popĆup) ➞ Configure (main) ➞ Hardcopy (Talk Only) (side).
To set up the communication parameters to talk to a printer attached directly
to the oscilloscope RSĆ232 port:
Press SHIFT UTILITY ➞ System (main) ➞ I/O (popĆup) ➞ Port ➞
RS232 (popĆup) ➞ Hardware Setup (main).
Press the sideĆmenu Baud Rate, Stop Bits, Parity and Hard Flagging
items and enter data as desired to match the hardcopy device
(see Figure 3Ć31).
Press Software Setup (main) and toggle the sideĆmenu Soft Flagging item
to turn software flagging on or off as desired.
Figure 3Ć31:ăUtility Menu Ċ System I/O
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Hardcopy
Setting Hardcopy Parameters
To specify the hardcopy format, layout, and type of port using the hardcopy
menu:
1. Press SHIFT HARDCOPY MENU to bring up the Hardcopy menu.
2. Press Format (main) ➞ Thinkjet, Deskjet, Laserjet, Epson, DPUĆ411,
DPUĆ412, PCX, PCXColor (TDS 644A),TIFF, BMP Mono, BMP Color
(TDS 644A),RLE Color (TDS 644A),EPS Mono Img, EPS Color Image
(TDS 644A),EPS Mono Plt, EPS Color Plt, Interleaf, or HPGL (side).
(Press -more- (side) to see all of these format choices.)
3. Press SHIFT HARDCOPY MENU ➞ Layout (main) ➞ Landscape or
Portrait (side) (see Figure 3Ć32).
Landscape Format
Portrait Format
Figure 3Ć32:ăHardcopy Formats
4. Press SHIFT HARDCOPY MENU ➞ Port (main) to specify the output
channel to sendyour hardcopy through. The choices are GPIB,
RSĆ232, Centronics, and File (RSĆ232, Centronics, andFile are optional
on the TDS 620A & TDS 640A).
If you choose File, the fileĆlist scrollbar will appear. Turn the general
purpose knob to select the desired file.
5. For hardcopy formats that support palettes, press SHIFT HARDCOPY
MENU ➞ Palette (main) ➞ Hardcopy or Current (side). Choose HardĆ
copy to have the hardcopy created using the Hardcopy Preview palette
in the Color Palette menu. The default settings for this palette provide a
white background. Choose Current to have the hardcopy created in
colors that closely match the current display.
Printing the Hardcopy
You can print a single hardcopy or send additional hardcopies to the spool
(queue) while waiting for earlier hardcopies to finish printing. To print your
hardcopy(ies):
Press HARDCOPY to print your hardcopy.
While the hardcopy is being sent to the printer, the oscilloscope will display
the message Hardcopy in process Ċ Press HARDCOPY to abort."
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Hardcopy
To stop and discard the hardcopy being sent, press HARDCOPY again
while the hardcopy in process message is still on screen.
To add additional hardcopies to the printer spool, press HARDCOPY again
after the hardcopy in process message is removed from the screen.
You can add hardcopies to the spool until it is full. When the spool is filled by
adding a hardcopy, the message Hardcopy in Process Ċ Press HARDCOĆ
PY to abort" remains displayed. You can abort the last hardcopy sent by
pressing the button while the message is still displayed. When the printer
empties enough ofthe spool to ifnish adding the last hardcopy it does so
and then removes the message.
To remove all hardcopies from the spool:
Press SHIFT HARDCOPY MENU ➞ Clear Spool (main) ➞ OK Confirm
Clear Spool (side).
This oscilloscope takes advantage ofany unused RAM when spooling
hardcopies to printers. The size ofthe spool is, therefore, variable. The
number ofhardcopies that can be spooled depends on three variables:
H
H
H
the amount ofunused RAM
the hardcopy format chosen
the complexity ofthe display
Although not guaranteed, usually about 2.5 hardcopies can be spooled
before the oscilloscope must wait to send the rest of the third copy.
Date/Time Stamping Your Hardcopy
You can display the current date and time on screen so that they appear on
the hardcopies you print. To date and time stamp your hardcopy:
1. Press DISPLAY ➞ Readout Options (main) ➞ Display Date and Time
(side) to toggle the setting to On.
2. Press Clear Menu to remove the menu from the display so the date and
time can be displayed (see Figure 3Ć33). (The date and time are reĆ
moved from the display when menus are displayed.)
3. Press HARDCOPY to print your date/time stamped hardcopy.
Ifyou need to set the date and time ofthe oscilloscope:
4. Press SHIFT UTILITY ➞ Config (popĆup) ➞ Set Date & Time (main) ➞
Year, Day Month, Hour, or Minute.
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Hardcopy
Date and Time Display
Figure3Ć33:ăDateand TimeDisplay
5. Use the generalpurpose knob or the keypad to set the parameter you
have chosen to the value desired. (The format when using the keypad is
rd
day.month. For example, use 23.6 for the 23 of June.)
6. Repeat steps 4 and 5 to set other parameters as desired.
7. Press OK Enter Date/Time (side) to put the new settings into effect.
This sets the seconds to zero.
NOTE
When setting the clock, you can set to a time slightly later than the
current time and wait for it to catch up. When current time catches
up to the time you have set, pressing Ok Enter Date/Time (side)
synchronizes the set time to the current time.
8. Press CLEAR MENU to see the date/time displayed with the new setĆ
tings.
9. Press HARDCOPY to print your date/time stamped hardcopy.
The ability of the digitizing oscilloscope to print a copy of its display in many
formats (see page 3Ć57) gives you flexibility in choosing a hardcopy device.
It also makes it easier for you to place oscilloscope screen copies into a
desktop publishing system.
Connection
Strategies
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Hardcopy
Strategies for actually printing a copy include:
H
H
Send output straight to a printer/plotter.
Send the datato acomputer to print from there and/or to import into
your favorite desktop publishing or other application package.
H
Send your datato afloppy disk file (optional on the TDS 620A &
TDS 640A) for later printing from a computer capable of reading the
MSĆDOS compatible floppy disk.
Printing Directlyto a HardcopyDevice
You can connect the digitizing oscilloscope directly to a hardcopy device
(see Figure 3Ć34). An example of a GPIB hardcopy device is the Tektronix
HC100 Plotter. Many printers, such as the Tektronix HC220, use Centronics
interfaces. Many hardcopy devices, including the HC100 with option 03,
provide RSĆ232 support.
Digitizing
Oscilloscope
Hardcopy Device
(e.g., Tek HC100)
GPIB, RSĆ232, or Centronics Cable
Figure 3Ć34:ăConnecting the Digitizing Oscilloscope Directlyto the
HardcopyDevice
Using a Controller
You can put a controller with two ports between the digitizing oscilloscope
and the hardcopy device (see Figure 3Ć35). Use a GPIB port to remotely
request and receive a hardcopy from the digitizing oscilloscope. Use an
RSĆ232 or aCentronics port on the controller to print output.
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Hardcopy
GPIB Cable
Centronics or
RSĆ232 Cable
PC Compatible
Digitizing
Oscilloscope
Hardcopy Device
Figure 3Ć35:ăConnecting the Digitizing Oscilloscope and Hardcopy
Device Via a PC
If your controller is PCĆcompatible and it uses the Tektronix GURU or
S3FG210 (National Instruments GPIBĆPCII/IIA) GPIB package, you can
operate this setup as follows:
1. Use the MSĆDOS cd command to move to the directory that holds the
software that came with your GPIB board. For example, if you installed
the software in the GPIBĆPC directory, type: cd GPIBĆPC
2. Run the IBIC program that came with your GPIB board. Type: IBIC
3. Type: IBFIND DEV1 where DEV1" is the name for the digitizing oscilloĆ
scope you defined using the IBCONF.EXE program that came with the
GPIB board.
NOTE
If you defined another name then, of course, use it instead of
DEV1". Also, remember that the device address of the digitizing
oscilloscope as set with the IBCONF.EXE programshould match
the address set in the digitizing oscilloscope Utility menu (typically,
use 1").
4. Type: IBWRTHARDCOPY START" Be sure the digitizing oscilloscope
Utility menu is set to Talk/Listenand not Hardcopy (Talk Only)or you
will get an error message at this step. Setting the digitizing oscilloscope
Utility menu was described in the start of this Hardcopy section under
the heading Setting Communication Parameters. Be sure to set the
controller timeĆout longer than the time required to transfer the hardcoĆ
py.
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Hardcopy
5. Type: IBRDF <Filename>where <Filename> is a valid DOS file name
you want to call your hardcopy information. It should be v8 characters
long with up to a 3 character extension. For example, you could type
ibrdf screen1".
6. Exit theIBIC program by typing: EXIT
7. Type: COPY <Filename> <Output port> </B> where <Filename> is
the name you defined in step 5 and <Output port> is the PC output
port your hardcopy device is connected to (such as LPT1 or LPT2).
Copy the data from your file to your hardcopy device. First, ensure your
printer or plotter is properly attached to your PC. Then copy the file. For
example, if your file is called screen1 and your printer is attached to the
lpt1 parallel port, type copy screen1 lpt1: /B".
NOTE
If you transmit hardcopy files across a computer network, use a
binary (8Ćbit) data path.
Your hardcopy deviceshould now print a pictureof thedigitizing oscilloĆ
scope screen.
See Remote Communication, on page3Ć116.
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Help
The onĆline help system provides brief information about each of the digitizĆ
ing oscilloscope controls.
To use the onĆline help system:
Operation
Press HELP to provide onĆscreen information on any front panel button,
knob or menu item (see Figure 3Ć36).
When you press that button, the instrument changes mode to support
onĆline help. Press HELP again to return to regular operating mode. WhenevĆ
er the oscilloscope is in help mode, pressing any button (except HELP or
SHIFT), turning any knob, or pressing any menu item displays help text on
the screen that discusses that control.
The menu selections that were displayed when HELP was firstpressed
remain on the screen. OnĆline help is available for each menu selection
displayed at the time the HELP button was first pressed. If you are in help
mode and want to see help on selections from nonĆdisplayed menus, you
firstexithelp mode, display the menu you wantinformation on, and press
HELP again to reĆenter help mode.
Figure 3Ć36:ăInitial HelpScreen
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Horizontal Control
You can control the horizontal part of the display (the time base) using the
horizontal menu and knobs.
By changing the horizontal scale, you can focus on a particular portion of a
waveform. By adjusting the horizontal position, you can move the waveform
rightor leftto see differentportions of the waveform. Thatis particularly
useful when you are using larger record sizes and cannot view the entire
waveform on one screen.
Horizontal Knobs
To change the horizontal scale and position, use the horizontal POSITION
and horizontal SCALE knobs (see Figure 3Ć37). These knobs manage the
time base and horizontal waveform positioning on the screen. When you use
either the horizontal SCALE or POSITION knobs, you affectall the waveĆ
form records displayed.
When you use either the horizontal SCALE or POSITION knobs, you affect
all displayed waveform records. If you wantthe POSITION knob to move
faster, press the SHIFT button. When the light above the shift button is on
and the display says Coarse Knobs in the upper right corner, the POSIĆ
TION knob speeds up significantly.
Figure 3Ć37:ăHorizontal Controls
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Horizontal Control
At the topof the display, the Record View shows the size and location of the
waveform record and the location of the trigger relative to the display (see
Figure 3Ć38). The Time Base readout at the lower right of the display shows
the time/division settings and the time base (main or delayed) being referred
to (see Figure 3Ć38).
Horizontal Readouts
Record View Readout
Time Base Readout
Figure 3Ć38:ăRecordView andTime Base Readouts
The Horizontal menu lets you select either a main or delayed view of the
time base for acquisitions. It also lets you set the record length, set the
trigger position, and change the position or scale.
Horizontal Menu
Main andDelayedTime Base
To select between the Main and Delayed views of the time base:
Press HORIZONTAL MENU ➞ Time Base (main)➞ Main Only, Intensified,
or DelayedOnly (side).
By pressing Intensified, you display a colored or intensified zone that
shows where the delayed trigger record length could occur relative to the
main trigger. The start of the zone corresponds to the possible start point of
the delayed trigger. The end of the zone corresponds to the end of the
delayed view of the time base.
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Horizontal Control
You also can select DelayedRuns After Main or DelayedTriggerable . For
more information on how to use these two menu items, see Delayed TriggerĆ
ing on page 3Ć20.
Trigger Position
To define how much of the record will be pretrigger and how much posttrigĆ
ger information using the Trigger Position menu item:
Press HORIZONTAL MENU ➞ Trigger Position (main)➞ Set to 20%, Set
to 50%, or Set to 80% (side), or use the general purpose knob or the keyĆ
pad to change the value.
RecordLength andFit To Screen
To set the waveform record length, press HORIZONTAL MENU ➞ Record
Length (main). The side menu lists various discrete record length choices.
To fit an acquired waveform to the visible screen, regardless of record
length, press HORIZONTAL MENU ➞ RecordLength (main). Then toggle
Fit to Screen to ON from the side menu. This provides similar functionality
to being in zoom mode and changing the time/division until the waveform
fits the screen. To turn off this feature, toggle Fit to Screen to OFF.
Horizontal Scale
To change the horizontal scale (time per division) numerically in the menu
instead of using the Horizontal SCALE knob:
Press HORIZONTAL MENU ➞ Horiz Scale (main) ➞ Main Scale or
DelayedScale (side), and use the keypad or the general purpose knob to
change the scale values.
Horizontal Position
You can set the horizontal position to specific values in the menu instead of
using the Horizontal POSITION knob.
Press HORIZONTAL MENU ➞ Horiz Pos (main) ➞ Set to 10%, Set to 50%
or Set to 90% (side) to choose how much of the waveform will be displayed
to the left of the display center.
You can also control whether changing the horizontal position setting affects
all displayed waveforms, just the live waveforms, or only the selected waveĆ
form. The Horizontal Locksetting in the Zoom menu determines which
waveforms the horizontal position knob adjusts whether zoom is on or not.
Specifically, it acts as follows:
H
H
None Ċ only the waveform currently selected can be zoomed and
positioned horizontally
Live Ċ all channels (including AUX channels for the TDS 620A) can be
zoomed and positioned horizontally at the same time
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Horizontal Control
H
All Ċ all waveforms displayed (channels, math, and/or reference) can
be zoomed and positioned horizontally at the same time
See Zoom, on page 3Ć151 for the steps to set the horizontal lock feature.
See Scaling and Positioning Waveforms, on page 2Ć22.
See Delayed Triggering, on page 3Ć20.
See Zoom, on page 3Ć151.
For More
Information
See Display Modes, on page 3Ć26.
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Limit Testing
Limit testing provides a way to automatically compare each incoming or
math waveform against a template waveform. You set an envelope of limits
around a waveformand let the digitizing oscilloscope find waveforms that
fall outside those limits (see Figure 3Ć39). When it finds such a waveform,
the digitizing oscilloscope can generate a hardcopy, ring a bell, stop and
wait for your input, or any combination of these actions.
Figure 3Ć39:ăComparing a Waveform to a Limit Template
When you use the limit testing feature, the first task is to create the limit test
template from a waveform. Next, specify the channel to compare to the
template. Then you specify the action to take if incoming waveform data
exceeds the set limits. Finally, turn limit testing on so that the parameters
you have specified will take effect.
To access limit testing:
Operation
Press SHIFT ACQUIRE MENU to bring up the Acquire menu.
Create Limit Test Template
To use an incoming or stored waveform to create the limit test template, first
select a source.
1. Press Create Limit Test Template (main) ➞ Template Source (side) ➞
Ch1, Ch2, Math1, Math2, Math3, Ref1, Ref2, Ref3, or Ref4 (side).
(See Figure 3Ć40).
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Limit Testing
NOTE
The template will be smoother if you acquire the template waveform
using Average acquisition mode. If you are unsure how to do this,
see Acquisition Modes on page 3Ć5.
Once you have selected a source, select a destination for the template.
2. Press Template Destination (side) ➞ Ref1, Ref2, Ref3, or Ref4.
Figure 3Ć40:ăAcquire Menu Ċ Create Limit Test Template
Now create the envelope by specifying the amount of variation from the
template that you will tolerate. Tolerance values are expressed in fracĆ
tions of a major division. They represent the amount by which incoming
waveformdata can deviate without having exceeded the limits set in the
limit test. The range is from 0 (the incoming waveform must be exactly
like the template source) to 5Ămajor divisions of tolerance.
3. Press ±V Limit (side). Enter the vertical (voltage) tolerance value using
the general purpose knob or keypad.
4. Press ±H Limit (side). Enter the horizontal (time) tolerance value using
the general purpose knob or keypad.
5. When you have specified the limit test template as you wish, press OK
Store Template (side). This action stores the specified waveformin the
specified destination, using the specified tolerances. Until you have
done so, the template waveform has been defined but not created.
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Limit Testing
If you wish to create another limit test template, store it in another desĆ
tination to avoid overwriting the template you have just created.
If you wish to view the template you have created, press the MORE
button. Then press the button corresponding to the destination referĆ
ence memory you have used. The waveform appears on the display.
NOTE
To view the waveform data as well as the template envelope, it
might be useful to select the Dots displaystyle (see Display Modes
on page 3Ć26).
Limit Test Sources
Now specify the channel that will acquire the waveforms to be compared
against the template you have created.
1. Press SHIFT ACQUIRE MENU ➞ Limit Test Sources (main) ➞
Compare Ch1 to, Compare Ch2 to, Compare Ch3 to, Compare Ch4
to, Compare Math1 to, Compare Math2 to or Compare Math3 to
(side).
2. Once you have selected one of the four channels or a math waveform as
a waveform source from the side menu, press the same side menu
button to select one of the reference memories in which you have stored
a template.
Valid selections are any of the four reference waveforms Ref1 through
Ref4 or None. Choosing None turns limit testing off for the specified
channel.
NOTE
Specifythe same reference memoryyou chose as the template
destination if you wish to use the template you just created.
If you have created more than one template, you can compare one
channel to one template and the other channel to another template.
Limit Test Setup
Now specify the action to take if waveform data exceeds the limits set by the
limit test template.
1. Press SHIFT ACQUIRE MENU ➞ Limit Test Setup (main) tobring up a
side menu of possible actions.
2. Ensure that the side button corresponding to the desired action reads
ON.
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Limit Testing
H
If you want to send a hardcopy command when waveform data
exceeds the limits set, toggle Hardcopy if Condition Met (side) to
ON. You can set the hardcopy system to send the hardcopy to the
file system (optional on the TDS 620A & TDS 640A). (Do not forget
to set up the hardcopy system. See Hardcopy on page 3Ć57 for
details.)
H
H
If you want the bell to ringwhen waveform data exceeds the limits
set, toggle Ring Bell if Condition Met (side) to ON.
If you want the digitizing oscilloscope to stop when waveform data
exceeds the limits set, toggle Stop After Limit Test Condition Met
(side) to ON.
NOTE
The button labeled Stop After Limit Test Condition Met correĆ
sponds to the Limit Test Condition Met menu item in the Stop
After main menu. You can turn this button on in the Limit Test
Setup menu, but you cannot turn it off. In order to turn it off, press
Stop After and specify one of the other choices in the Stop After
side menu.
Now that you have set up the instrument for limit testing, you must turn
limit testingon in order for any of these actions to take effect.
3. Ensure that Limit Test (side) reads ON. If it reads OFF, press Limit Test
(side) once to toggle it to ON.
When you set Limit Test to ON, the digitizing oscilloscope compares
incomingwaveforms against the waveform template stored in reference
memory accordingto the settings in the Limit Test Sources side menu.
You can compare a single waveform against a single template, more than
one waveform against a single template, or more than one waveform with
each one compared against its own template. How Limit Test operates
depends on which type of these comparisons you choose.
Single and Multiple
Waveforms
Single Waveform Comparisons
When making a single waveform versus a single template comparison,
consider the followingoperatingcharacteristics:
H
The waveform will be repositioned horizontally to move the first sample
in the waveform record that is outside of template limits to center
screen.
H
The position of the waveform template will track that of the waveform.
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Limit Testing
Multiple Waveform Comparisons
When comparing one or more waveforms, each against a common template
or against its own template, consider the following operating characteristics:
H
H
You should set Horizontal Lock to None in the Zoom side menu (push
ZOOM and press (repeatedly) Horizontal Lock to None).
With horizontal lock set as just described, the oscilloscope will reposition
each waveform horizontally to move the first sample in the waveform
record that is outside of template limits to center screen.
H
H
If you are comparing each waveform to its own template, the position of
each waveform template will track that of its waveform.
If you are comparing two or more waveforms to a common template,
that template will track the position of the failed waveform. If more than
one waveform fails during the same acquisition, the template will track
the position of the waveform in the highest numbered channel. For
example, CH 2 is higher than CH 1.
See Acquisition, on page 2Ć19.
See Acquisition Modes, on page 3Ć3.
See Display Modes, on page 3Ć26.
See Zoom, on page 3Ć151.
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Logic Triggering
There are two classes of logic triggering: pattern andstate.
A pattern trigger occurs when the logic inputs to the logic function you select
cause the function to become TRUE (or at your option FALSE). When you
use a pattern trigger, you define:
H
The precondition for each logic input Ċ logic high, low, or do not care
(the logic inputs are channels 1, 2, 3, and4 for the TDS 640A &
TDS 644A and1, 2, Aux 1, andAux 2 for the TDS 620A)
H
H
The Boolean logic function Ċ select from AND, NAND, OR, andNOR
The condition for triggering Ċ whether the trigger occurs when the
Boolean function becomes TRUE (logic high) or FALSE (logic low), and
whether the TRUE condition is time qualified (see page 3Ć80).
A state trigger occurs when the logic inputs to the logic function cause the
function to be TRUE (or at your option FALSE) at the time the clock input
changes state. When you use a state trigger, you define:
H
H
H
H
The precondition for each logic input, channels 1, 2, and 3 for the
TDS 640A & TDS 644A (1, 2, andAx1 on the TDS 620A)
The direction of the state change for the clock input, channel 4 (Aux 2
for the TDS 620A)
The Boolean logic function Ċ select from clockedAND, NAND, OR, and
NOR
The condition for triggering Ċ whether the trigger occurs when the
Boolean function becomes TRUE (logic high) or FALSE (logic low)
Table 3Ć3 on page 3Ć77 lists the preconditions required for each logic funcĆ
tion to issue a pattern or state logic trigger.
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Logic Triggering
At the bottom of the display, the Trigger readout shows some of the key
parameters of the logic trigger (see Figure 3Ć41).
Logic Trigger
Readouts
Ch 1, 2, 3 Inputs= High, Don't Care, High
Ch 4 Input =
Rising Edge
Trigger Class = State
Logic = OR
Figure 3Ć41:ăLogic Trigger Readouts
NOTE
When Logic is the selected trigger type, the threshold levels that
help determine triggering are set for each channel individuallyin
the Set Thresholds menu. Therefore, the Trigger Level readout will
disappear on the displayand the Trigger Level knob can be used
to set the threshold level while the Main Trigger menu is set to
Logic.
Table 3Ć3 lists the definitions for the four types of logic functions available.
Keep in mind the following operating modes for the two classes, pattern and
state, of logic triggers as you apply the definitions.
Definitions
Pattern Ċ At the end of trigger holdoff, the oscilloscope samples the inputs
from all the channels. The oscilloscope then triggers if the conditions deĆ
fined in Table 3Ć3 are met. (GoesTRUE or GoesFALSE must be set in the
Trigger When menu. The other settings in that menu are described in
Define a Time Qualified Pattern Trigger on page 3Ć80.)
State Ċ At the end of trigger holdoff, the oscilloscope waits until the edge
of channel 4 (Aux 2 on the TDS 620A) transitions in the specified direction.
At that point, the oscilloscope samples the inputs from the other channels
and triggers if the conditions defined in Table 3Ć3 are met.
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Logic Triggering
TableĂ3Ć3:ăLogic Triggers
State Definition
1,2
Pattern
AND
Clocked AND
If all the preconditions selected
for the logic inputs are true,
3
then the oscilloscope triggers.
NAND
Clocked NAND If not all of the preconditions seĆ
3
lected for the logic inputs are
true, then the oscilloscope trigĆ
gers.
OR
Clocked OR
If any of the preconditions seĆ
lected for the logic inputs are
3
true, then the oscilloscope trigĆ
gers.
NOR
Clocked NOR
If none of the preconditions seĆ
lected for the logic inputs are
3
true, then the oscilloscope trigĆ
gers.
1
Note that for State class triggers, the definition must be met at the time the clock input
changes state. See the descriptions for Pattern and State in this section.
2
The definitions given here are correct for the Goes True setting in the Trigger When menu.
If that menu is set to Goes False, swap the definition for AND with that for NAND and for OR
with NOR for both pattern and state classes.
3
The logic inputs are channels 1, 2, 3, and 4 for the TDS 640A & TDS 644A and 1, 2, Aux 1
and Aux 2 for the TDS 620A when using Pattern Logic Triggers. For State Logic Triggers,
channel 4 (Aux 2 for the TDS 620A) becomes the clock input, leaving the remaining chanĆ
nels as logic inputs.
The Logic Trigger menu (Figure 3Ć42) lets you select when to trigger (true or
false), set the thresholds for each channel, select the mode (auto or normal),
and adjust the holdoff.
Operations Common
to Pattern and State
Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern or State (popĆup).
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Logic Triggering
Figure 3Ć42:ăLogic Trigger Menu
Trigger When
This menu item lets you determine if the oscilloscope will trigger when the
logic condition is met (Goes TRUE) or when the logic condition is not met
(Goes FALSE). (The True when less than and True when greater than
menu items are only used for pattern logic triggering and are covered on
page 3Ć80.)
Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern or State (popĆup) ➞ Trigger When (main) ➞ Goes
TRUE or Goes FALSE (side).
Set Thresholds
To set the logic threshold for each channel:
1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern or State (popĆup) ➞ Set Thresholds (main) ➞
Ch1, Ch2, Ch3 (Ax1 on the TDS 620A), or Ch4 (Ax2 on the TDS 620A)
(side).
2. Use the MAIN TRIGGER LEVEL knob, the general purpose knob, or the
keypad toset each threshold.
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Logic Triggering
Mode & Holdoff
You can changetheholdoff timeand select thetrigger modeusing this
menu item.
1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern or State (popĆup) ➞ Mode & Holdoff (main) ➞
Auto or Normal (side).
H
In Auto mode the oscilloscope acquires a waveform after a specific
time has elapsed even if a trigger does not occur. The amount of
timetheoscilloscopewaits depends on thetimebasesetting.
H
In Normal modetheoscilloscopeacquires a waveform only if there
is a valid trigger.
2. Press Holdoff (side). Enter the value in percent using the general purĆ
poseknob or thekeypad.
Depending on whether you chose the class Pattern or State, there are
different menus for defining the channel inputs and the combinational logic.
When you select Pattern, the oscilloscope will trigger on a specified logic
combination of the four input channels. See page 3Ć77 for details on operaĆ
tions common to both pattern and state triggers.
Pattern Operations
Define Inputs
To set thelogic statefor each of theinput channels (
Ch1, Ch2, ...):
1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern (popĆup) ➞ Define Inputs (main) ➞ Ch1, Ch2,
Ch3, or Ch4 (side). (On the TDS 620A, Ch3 and Ch4 are replaced by
Ax1 and Ax2.)
2. Repeatedly press each input selected in step 1 to choose either High
(H), Low (L), or Don't Care( X) for each channel.
Define Logic
To choosethelogic function you want applied to theinput channels (see
page3Ć76 for definitions of thelogic functions for both pattern and state
triggers):
Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern (popĆup) ➞ Define Logic (main) ➞ AND, OR,
NAND, or NOR (side).
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Logic Triggering
Define a Time Qualified Pattern Trigger
You can also time qualify a pattern logic trigger. That is, you specify a time
that the boolean logic function (AND, NAND, OR, or NOR) must be TRUE
(logic high). You also choose the type of time qualification (greater or less
than the time limit specified) as well as the time limit using the Trigger When
menu selection.
1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ Pattern (popĆup) ➞ Trigger When (main) ➞ True for
less than or True for more than (side).
2. Use the knob andkeypadto set the time in the side menu.
When you select True for less than andspecify a time using the general
purpose knob, the input conditions you specify must drive the logic function
high (TRUE) for less than the time you specify. Conversely, True for more
than requires the boolean function to be TRUE for longer than the time you
specify.
Note the position of the trigger indicator in Figure 3Ć43. Triggering occurs at
the point the logic function you specify is determined to be true within the
time you specify. The digitizing oscilloscope determines the trigger point in
the following manner:
H
H
H
It waits for the logic condition to become true
It starts timing andwaits for the logic function to become false
It compares the times and, if the time TRUE is longer (for True for more
than) or shorter (for True for less than), then it triggers a waveform
display at the point the logic condition became false. This time can be,
andusually is, different from the time set for True for more than or True
forless than .
In Figure 3Ć43, the delay between the vertical bar cursors is the time the
logic function is TRUE. Since this time is more (216 ms) than that set in the
True for more than menu item (150 ms), the oscilloscope issues the trigger
at that point, not at the point at which it has been true for 216 ms.
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Logic Triggering
Time Logic Function is TRUE
Logic Function (AND) Becomes TRUE
Logic Function Becomes FALSE and
Triggers Acquisition
Time Logic Function Must be TRUE
Figure 3Ć43:ăLogic Trigger Menu Ċ Time Qualified TRUE
When you select State logic triggering, the oscilloscope uses channel 4
(Aux 2 on the TDS 620A) as a clock for a logic circuit made from the rest of
the channels. See page 3Ć77 for details on operations common to both
pattern and state triggers.
StateOperations
The state trigger logic works as follows: the oscilloscope waits until the
fourth channel meets the selected slope and voltage threshold. It then
checks the logic function applied to the first three channels, and if the funcĆ
tion condition is as specified in the the Trigger When menu (Goes TRUE or
Goes FALSE) a trigger occurs.
Define Inputs
To set the logic state for each of the input channels (Ch1, Ch2, ...):
1. Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ State (popĆup) ➞ Define Inputs (main).
2. Choose either High (H), Low (L), or Don't Care (X) (side) for the first
three channels. The choices for Ch4 (Aux 2 on the TDS 620A) are rising
edge and falling edge.
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Logic Triggering
Define Logic
To choose the type of logic function you want applied to the input channels:
Press TRIGGER MENU ➞ Type (main) ➞ Logic (popĆup) ➞
Class (main) ➞ State (popĆup) ➞ Define Logic (main) ➞ AND, OR,
NAND, or NOR (side).
See Triggering, on page 2Ć13.
For More
Information
See Triggering, on page 3Ć132.
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Measurement System
There are various ways to measure properties of waveforms. You can use
graticule, cursor, or automatic measurements. This section describes autoĆ
matic measurements; cursors and graticules are described elsewhere. (See
Cursor Measurements on page 3Ć15 and Measurements on page 2Ć26.)
Automatic measurements are generally more accurate and quicker than, for
example, manually countinggraticule divisions. The oscilloscope will continĆ
uously update and display these measurements. (There is also a way to
display all the measurements at once Ċ seeSnapshot of Measurements on
page 3Ć92.)
Automatic measurements calculate waveform parameters from acquired
data. Measurements are performed over the entire waveform record or the
region specified by the vertical cursors, if gated measurements have been
requested. (See page 3Ć88 for a discussion of gated measurements.) They
are not performed just on the displayed portions of waveforms.
The TDS 600A Digitizing Oscilloscope provides you with 25 automatic meaĆ
surements (see Table 3Ć4).
The followingare brief definitions of the automated measurements in the
digitizing oscilloscope (for more details see Appendix C: Algorithms,
page AĆ7).
Definitions
TableĂ3Ć4:ăMeasurement Definitions
Name
Definition
Amplitude
Voltage measurement. The high value less the low value measured over the
entire waveform or gated region.
Amplitude = High - Low
Area
Voltage over time measurement. The area over the entire waveform or gated
region in voltĆseconds. Area measured above ground is positive; area below
ground is negative.
Cycle Area
Voltage over time measurement. The area over the first cycle in the waveform,
or the first cycle in the gated region, in voltĆseconds. Area measured above
ground is positive; area below ground is negative.
Burst Width
Cycle Mean
Cycle RMS
Timingmeasurement. The duration of a burst. Measured over the entire waveĆ
form or gated region.
Voltage measurement. The arithmetic mean over the first cycle in the waveĆ
form or the first cycle in the gated region.
Voltage measurement. The true Root Mean Square voltage over the first cycle
in the waveform or the first cycle in the gated region.
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Measurement System
TableĂ3Ć4:ăMeasurement Definitions (Cont.)
Definition
Name
Delay
Timing measurement. The time between the MidRef crossings of two different
traces or the gated region of the traces.
Fall Time
Frequency
High
Timing measurement. Time taken for the falling edge of the first pulse in the
waveform or gated region to fall from a High Ref value (default = 90%) to a
Low Ref value (default =10%) of its final value.
Timing measurement for the first cycle in the waveform or gated region. The
reciprocal of the period. Measured in Hertz (Hz) where 1 Hz = 1 cycle per
second.
The value used as 100% whenever High Ref, Mid Ref, and Low Ref values are
needed (as in fall time and rise time measurements). Calculated using either
the min/max or the histogram method. The min/max method uses the maxiĆ
mum value found. The histogram method uses the most common value found
above the mid point. Measured over the entire waveform or gated region.
Low
The value used as 0% whenever High Ref, Mid Ref, and Low Ref values are
needed (as in fall time and rise time measurements). May be calculated using
either the min/max or the histogram method. With the min/max method it is
the minimum value found. With the histogram method, it refers to the most
common value found below the mid point. Measured over the entire waveform
or gated region.
Maximum
Mean
Voltage measurement. The maximum amplitude. Typically the most positive
peak voltage. Measured over the entire waveform or gated region.
Voltage measurement. The arithmetic mean over the entire waveform or gated
region.
Minimum
Voltage measurement. The minimum amplitude. Typically the most negative
peak voltage. Measured over the entire waveform or gated region.
Negative Duty
Cycle
Timing measurement of the first cycle in the waveform or gated region. The
ratio of the negative pulse width to the signal period expressed as a percentĆ
age.
NegativeWidth
NegativeDutyCycle +
100%
Period
Negative OverĆ
shoot
Voltage measurement. Measured over the entire waveform or gated region.
Low * Min
NegativeOvershoot +
100%
Amplitude
Negative Width
Timing measurement of the first pulse in the waveform or gated region. The
distance (time) between MidRef (default 50%) amplitude points of a negative
pulse.
Peak to Peak
Phase
Voltage measurement. The absolute difference between the maximum and
minimum amplitude in the entire waveform or gated region.
Timing measurement. The amount one waveform leads or lags another in
time. Expressed in degrees, where 360° comprise one waveform cycle.
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Measurement System
TableĂ3Ć4:ăMeasurement Definitions (Cont.)
Definition
Name
Period
Timing measurement. Time it takes for the first complete signal cycle to hapĆ
pen in the waveform or gated region. The reciprocal of frequency. Measured
in seconds.
Positive Duty
Cycle
Timing measurement of the first cycle in the waveform or gated region. The
ratio of the positive pulse width to the signal period expressed as a percentĆ
age.
PositiveWidth
Period
PositiveDutyCycle +
100%
Positive OverĆ
shoot
Voltage measurement over the entire waveform or gated region.
Max * High
PositiveOvershoot +
100%
Amplitude
Positive Width
Rise time
RMS
Timing measurement of the first pulse in the waveform or gated region. The
distance (time) between MidRef (default 50%) amplitude points of a positive
pulse.
Timing measurement. Time taken for the leading edge of the first pulse in the
waveform or gated region to rise from a Low Ref value (default = 10%) to a
High Ref value (default = 90%) of its final value.
Voltage measurement. The true Root Mean Square voltage over the entire
waveform or gated region.
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Measurement System
The readout area for measurements is on the right side of the waveform
window. You can display and continuously update as many as four measureĆ
ments at any one time. When menus are displayed, the readouts appear in
the graticule area. If the menu area is empty, then the readouts are disĆ
played to the far right (see Figure 3Ć44).
Measurement Display
Measurement Readout Area
Figure 3Ć44:ăMeasurement Readouts
To use the automatic measurements you first need to obtain a stable display
of the waveformto be measured. Pressing AUTOSET may help. Once you
have a stable display, press MEASURE to bring up the Measure menu (see
Figure 3Ć45).
Operation
Selecting a Measurement
Measurements are made on the selected waveform. The measurement
display tells you the channel the measurement is being made on.
1. Press MEASURE ➞ Select Measrmnt (main).
2. Select a measurement from the side menu.
The following are hints on making automatic measurements:
H
You can only take a maximum of four measurements at a time. To
add a fifth, you must remove one or more of the existing measureĆ
ments.
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MeasurementSystem
H
H
To vary the source for measurements, simply select the other chanĆ
nel and then choose the measurements you want.
Be careful when taking automatic measurements on noisy signals.
You might measure the frequency of the noise and not the desired
waveform.
Your digitizing oscilloscope helps identify such situations by displaying a
low signal amplitude or low resolution warning message.
Figure 3Ć45:ăMeasure Menu
Removing Measurements
The Remove Measrmnt selection provides explicit choices for removing
measurements from the display according to their readout position.
Measurement 1 is the top readout. Measurement 2 is below it, and so forth.
Once a measurement readout is displayed in the screen area, it stays in its
position even when you remove any measurement readouts above it. To
remove measurements:
1. Press MEASURE ➞ Remove Measrmnt (main).
2. Select the measurement to remove from the side menu. If you want to
remove all the measurements at one time, press All Measurements
(side).
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Measurement System
Gated Measurements
The gating feature lets you limit measurements to a specified portion of the
waveform. When gating is Off, the oscilloscope makes measurements over
the entire waveformrecord.
When gating is activated, vertical cursors are displayed. Use these cursors
to define the section of the waveformyou want the oscilloscope to measure.
This is called the gated region.
1. Press MEASURE ➞ Gating (main) ➞ Gate with V Bar Cursors (side)
(see Figure 3Ć46).
Figure 3Ć46:ăMeasure Menu Ċ Gating
2. Using the general purpose knob, move the selected (the active) cursor.
Press SELECT to change which cursor is active.
Displaying the cursor menu and turning V Bar cursors off will not turn
gating off. (Gating arrows remain on screen to indicate the area over
which the measurement is gated.) You must turn gating off in the Gating
side menu.
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Measurement System
NOTE
Cursors are displayed relative to the selected waveform. If you are
making a measurement using two waveforms, this can be a source
of confusion. If you turn off horizontal locking and adjust the horiĆ
zontal position of one waveform independent of the other, the
cursors appear at the requested position with respect to the seĆ
lected waveform. Gated measurements remain accurate, but the
displayed positions of the cursors change when you change the
selected waveform.
HighĆLow Setup
The HighĆLow Setup item provides two choices for how the oscilloscope
determines the High and Low levels ofwaveforms. These are histogram and
minĆmax.
H
H
Histogram sets the values statistically. It selects the most common value
either above or below the mid point (depending on whether it is defining
the high or low reference level). Since this statistical approach ignores
short term aberrations (overshoot, ringing, etc.), histogram is the best
setting for examining pulses.
MinĆmax uses the highest and lowest values ofthe waveform record.
This setting is best for examining waveforms that have no large, flat
portions at a common value, such as sine waves and triangle waves Ċ
almost any waveform except for pulses.
To use the highĆlow setup:
Press MEASURE ➞ HighĆLow Setup (main) ➞ Histogram or MinĆMax
(side). Ifyou select MinĆMax, you may also want to check and/or revise
values using the Reference Levels main menu.
Reference Levels
Once you define the reference levels, the digitizing oscilloscope will use
them for all measurements requiring those levels. To set the reference levels:
1. Press MEASURE ➞ Reference Levels (main) ➞ Set Levels (side) to
choose whether the References are set in % relative to High (100%) and
Low (0%) or set explicitly in the units ofthe selected waveform (typically
volts). See Figure 3Ć47. Use the general purpose knob or keypad to
enter the values.
H
H
% is the default selection. It is useful for general purpose applicaĆ
tions.
Units is helpful for setting precise values. For example, if you are
trying to measure specifications on an RSĆ232ĆC circuit, you can set
the levels precisely to RSĆ232ĆC specification voltage values by
defining the high and low references in units.
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Measurement System
2. Press High Ref, Mid Ref, Low Ref, or Mid2 Ref (side).
H
H
H
H
High Ref Ċ Sets the high reference level. The default is 90%.
Mid Ref Ċ Sets the middle reference level. The default is 50%.
Low Ref Ċ Sets the low reference level. The default is 10%.
Mid2 Ref Ċ Sets the middle reference level used on the second
waveform specified in the Delay or Phase Measurements. The
default is 50%.
Figure 3Ć47:ăMeasure Menu Ċ Reference Levels
Delay Measurement
The delay measurement lets you measure from an edge on the selected
waveform to an edge on another waveform. You access the Delay MeasureĆ
ment menu through the Measure main menu:
Press MEASURE ➞ Select Measrmnt (main) ➞ Delay (side). This brings
up the Measure Delay main menu (see Figure 3Ć48).
Delay to Ċ To select the waveform you want to measure to, use the main
menu item Delay to. The waveform you are measuring from is the selected
waveform.
1. Press MEASURE ➞ Select Measrmnt (main) ➞ Delay (side) ➞ Delay
To (main) ➞ Measure Delay to.
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Measurement System
2. Press Measure Delay to (side) repeatedly to choose the delay to waveĆ
form. The choices are Ch1, Ch2, Ch3, Ch4 (on the TDS 644A &
TDS 640A); Ch1, Ch2, Ax1, Ax2 (on the TDS 620A); and Math1, Math2,
Math3, Ref1, Ref2, Ref3, and Ref4.
Figure 3Ć48:ăMeasure Delay Menu Ċ Delay To
Delay Edges Ċ The main menu item Edges lets you specify which edges
you want the delayed measurement to be made between.
Press MEASURE ➞ Select Measrmnt (main) ➞ Delay (side) ➞
Edges (main). A side menu of delay edges and directions will appear.
Choose from one of the combinations displayed on the side menu.
The upper waveform on each icon represents the from waveform and the
lower one represents the to waveform.
The direction arrows on the choices let you specify a forward search on both
waveforms or a forward search on the from waveform and a backwards
search on the to waveform. The latter choice is useful for isolating a specific
pair of edges out of a stream.
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Measurement System
Creating the Delay Measurement Ċ Once you have specified the
waveforms you are measuring between and which edges to use, you need
to notify the digitizing oscilloscope to proceed with the measurement.
Press Delay To (main) ➞ OK Create Measurement (side).
To exit the Measure Delay menu without creating a delay measurement,
press CLEAR MENU, which returns you to the Measure menu.
Sometimes you may want to see all of the automated measurements on
screen at the same time. To do so, use Snapshot. Snapshot executes all of
the single waveform measurements available on the selected waveform
once and displays the results. (The measurements are not continuously
updated.) All of the measurements listed in Table 3Ć4 on page 3Ć83 except
for Delay and Phase are displayed. (Delay and Phase are dual waveform
measurements and are not available with Snapshot.)
Snapshot of
Measurements
The readout area for a snapshot of measurements is a pop up display that
covers about 80% of the graticule area whendisplayed (see Figure 3Ć49).
You can display a snapshot on any channel or ref memory, but only one
snapshot can be displayed at a time.
Snapshot Display
Figure 3Ć49:ăSnapshot Menu and Readout
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To use snapshot, obtain a stable display ofthe waveform to be measured.
Pressing AUTOSET may help.
1. Press MEASURE ➞ SNAPSHOT (main).
2. Press either SNAPSHOT (main) orAGAIN (side) to take another snapĆ
shot.
NOTE
The snapshot display tells you the channel that the snapshot is
being made on.
3. Push Remove Measrmnt.
Considerations When TakingSnapshots
Be aware ofthe following items when using snapshot:
H
Be sure to display the waveform properly before taking a snapshot.
Snapshot does not warn you ifa waveform is improperly scaled
(clipped, low signal amplitude, low resolution, etc.).
H
H
To vary the source for taking a snapshot, simply select another channel,
math, or refmemory waveform and then execute snapshot again.
A snapshot is taken on a single waveform acquisition (or acquisition
sequence). The measurements in the snapshot display are not continuĆ
ously updated.
H
H
H
Be careful when taking automatic measurements on noisy signals. You
might measure the frequency of the noise and not the desired waveĆ
form.
Note that pushing any button in the main menu (except for Snapshot) or
any front panel button that displays a new menu removes the snapshot
from display.
Use HighĆLow Setup (page 3Ć89), Reference Levels (page 3Ć89), and
Gated Measurements (page 3Ć88) with snapshot exactly as you would
when you display individual measurements from the Select Measrmnt
menu.
See Appendix B: Algorithms, on page AĆ7.
For More
Information
See Measurements, on page 2Ć26.
See Tutorial Example 3: Automated Measurements, on page 1Ć18.
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Probe Cal
This oscilloscopelets you compensatetheentiresignal path, from probetip
to digitized signal, to improvethegain and offset accuracy of theprobe. By
executing Probe Cal on a channel with its probe installed, you can optimize
theoscilloscopecapability to makeaccuratemeasurements using that
channel and probe.
Run a ProbeCal anytimeyou wish to ensurethat themeasurements you
makearemadewith themost accuracy possible. You should also run a
ProbeCal if you havechanged to a different probesincethelast ProbeCal
was performed.
Probe Cal vs. Probe Type
Some types of probes can be gain compensated, some can be offset comĆ
pensated, and some can be compensated for both. Some probes cannot be
compensated.
If your probe has an attenuation factor of greater than 20X, it cannot be
compensated. If you attempt to compensate such a probe you will get an
error message.
Thedigitizing oscilloscopecannot compensateprobes whosegain and/or
offset errors are too great (u2% gain and/or u50 mV offset). If these errors
are within specified limits for your probe, you may wish to use another
probe. If they are not within specification, have your probe checked by
service personnel.
If you areinstalling an active probe, such as the P6205, there are no prereqĆ
uisites to performing this procedure. Start at step 1.
Operation
If you arecompensating for a passive probewith this procedureyou must
first compensate the low frequency response of the probe. First, do steps 1
and 2 below, and then perform the instructions found under Probe CompenĆ
sation on page 3Ć100. Then continue with step 3 of this procedure.
1. Install theprobeon theinput channel on which it is to beused.
2. Power on thedigitizing oscilloscopeand allow a 20 minutewarmĆup
before doing this procedure.
3. Press SHIFT UTILITY ➞ System (main) ➞ Cal (popĆup).
4. Look at the status label under Signal Path in themain menu. If the
status does not read Pass, perform a signal path compensation (Signal
Path Compensation, page 3Ć128), and then continue with this procedure.
5. Press the frontĆpanel button corresponding to the input channel on
which you installed the probe.
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Probe Cal
6. Press VERTICAL MENU ➞ Cal Probe (main).
Your oscilloscope will detect the type of probe you have installed
and display screen messages and menu choices for compensation
of probe gain, offset, or both (see Figure 3Ć50). The following steps
will have you run probe gain, offset, or both depending on the probe
the oscilloscope detects.
7. If the message on screen is Probe Offset Compensation rather than
Probe Gain Compensation, skip to step 15.
8. Connect the probe tip to PROBE COMPENSATION SIGNAL; connect
the probe ground lead to PROBE COMPENSATION GND.
9. Press OK Compensate Gain (side).
10. Wait for gain compensation to complete (one to three minutes).
When gain compensation completes, the following actions occur:
H
H
The clock icon will disappear.
If offset compensation is required for the probe installed, the Probe
Offset Compensation message will replace the Probe Gain CompenĆ
sation message.
H
H
If gain compensation did not complete successfully, you may get a
Probe is not connected" message (examine the probe connections
to the digitizing oscilloscope, be sure the probe tip is properly
installed in its retractor, etc., and repeat step 9).
If gain compensation did not complete successfully, you may get the
message Compensation Error." This error implies that the probe
gain (2% error) and/or offset (50 mV) is too great to be compenĆ
sated. You can substitute another probe and continue. Have your
probe checked by service personnel.
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Probe Cal
Figure 3Ć50:ăProbe Cal Menu and Gain Compensation Display
11. If the Probe Offset Compensation message is displayed, continue with
step 15; otherwise, continue with step 12.
12. If the Compensation Error message is displayed, continue with step 13;
otherwise continue with step 18.
13. Press SHIFT UTILITY ➞ System (main) ➞ Diag/Err (popĆup) ➞ Error
Log (main). If there are too many error messages to be seen on screen,
rotate the general purpose knob clockwise to scroll to the last message.
14. Note the compensation error amount. Skip to step 19.
15. Disconnect the probe from any signal you may have connected it to.
Leave the probe installed on its channel.
16. Press OK Compensate Offset (side).
17. Wait for offset compensation to complete (one to three minutes).
When offset compensation completes, the following occurs:
H
H
The clock icon will disappear.
If offset compensation did not complete successfully, you may get
the message Compensation Error." This error implies that the probe
offset scale (10% error) and/or offset (50 mV) is too great to be
compensated. You can substitute another probe and continue. Have
your probe checked by service personnel. You can also check the
error log by doing steps 13 through 14.
18. After the clock icon is removed, verify the word Initialized changed to
Pass under Cal Probe in the main menu. (See Figure 3Ć50.)
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Probe Cal
19. If desired, repeat this procedure beginning at step 1 to compensate for
other probe/channelcombinations. But before you do so, be sure you
take note of the following requirements:
H
H
Remember to first low frequency compensate any passive probe
you connect (see Prerequisites at the beginning of this procedure).
Remember to connect all but simple passive probes to the oscilloĆ
scope for a twenty minute warm up before running Probe Cal.
The following topic contains information you should consider when using
input channels that have stored a Probe Cal.
Usage
Changing Probes After a Probe Cal
If a Probe Calhas never been performed on an input channelor if its stored
Probe Caldata is erased using the ReĆuse Probe Calibration Data menu
(discussed later), the oscilloscope displays Initialized status in its vertical
menu. It also displays initialized whenever you remove a probe from an
input.
If you execute a successful Probe Cal on an input channel, the oscilloscope
stores the compensation data it derived in nonĆvolatile memory. Therefore,
this data is available when you turn the oscilloscope off and back on, when
you change probes, etc.
When you install a probe or power on the oscilloscope with probes installed,
the oscilloscope tests the probe at each input. Depending on the probe it
finds on each input, it takes one of the following actions:
H
If the probe has a complex oscilloscope interface (it can convey addiĆ
tional information, such as a unique identification number), the oscilloĆ
scope determines whether it is the same probe for which data was
stored. If it is, the oscilloscope sets status to pass; if not, it sets the
status to Initialized.
H
If a probe has a simple oscilloscope interface, the oscilloscope can
usually determine if it has a different probe attenuation factor than that
stored for the last Probe Cal. It can also determine if the last Probe Cal
was for a probe with a complex interface. If either is the case, the probe
installed is different from that stored for the last Probe Cal. Therefore,
the oscilloscope sets the status to Initialized.
H
If a probe has a simple oscilloscope interface and the probe attenuation
factor is the same as was stored at the last Probe Cal, the oscilloscope
cannot determine whether it is the same probe. Therefore, it displays the
ReĆuse Probe Calibration data? menu (see Figure 3Ć51).
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ProbeCal
Figure3Ć51:ăReĆuseProbeCalibration Data Menu
If the ReĆuse Probe Calibration data? menu is displayed, you can choose
one of the following options:
H
H
H
Press OK UseExisting Data (side) to use the Probe Cal data last stored
to compensate the probe.
Press OK EraseProbeCal Data (side) to erase the Probe Cal data last
stored and use the probe uncompensated.
Press CLEAR MENU on the front panel to retain the Probe Cal data last
stored and use the probe uncompensated.
Table 3Ć5 shows the action the oscilloscope takes based on the probe
connected and user operation performed.
TableĂ3Ć5:ăProbe Cal Status
2
Probe
User
TypeProbeConnected
1
3
4
Cal'd?
Action
SimpleInterface
Complex Interface
No
Doesn't
Matter
Initialized
Initialized
Yes
Yes
Power
off
Initialized
(probe data is retained)
Initialized
(probe data is retained)
Power
on
Can not detect different probe: Display ReĆuse Cal'd Probe:
Probe Calibration Data menu
Pass
Different probe:
Initialized
Different probe:
Initialized
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Probe Cal
TableĂ3Ć5:ăProbe Cal Status (Cont.)
Type Probe Connected
2
Probe
Cal'd?
Yes
User
1
3
4
Action
Simple Interface
Complex Interface
Disconnect Initialized
Initialized
Probe
Yes
Connect
Probe
Can not detect different probe: Display ReĆuse Cal'd Probe:
Probe Calibration Data menu
Pass
Different probe:
Initialized
Different probe:
Initialized
1
2
3
Refers to a channel input that was successfully compensatedat the time Probe Cal was last executedfor the input channel.
If no probe is connected, the probe status in the vertical main menu is always initialized.
A probe with a simple interface is a probe that can convey very limitedinformation to the oscilloscope. Most passive probes (such as
the standard accessory P6139A) have simple interfaces.
4
A probe with a complex interface is a probe that can convey additional information. For instance, it might automatically set the
oscilloscope input channel impedance to match the probe, send the oscilloscope a unique probe identification number, etc. Some
optical probes andmost active probes (including the optional P6205) have complex interfaces.
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Probe Compensation
Passive probes require compensation to ensure maximum distortionĆfree
input to the digitizing oscilloscope and to avoid high frequency amplitude
errors (see Figure 3Ć52).
Probe Compensated Correctly
Probe Overcompensated
Probe Undercompensated
Figure 3Ć52:ăHow Probe Compensation Affects Signals
To compensate your probe:
Operation
1. Connect the probe to the probe compensation signal on the front panel.
2. Press AUTOSET.
NOTE
When you connect an active probe to the oscilloscope (such as the
P6205), the input impedance of the oscilloscope automatically
becomes 50 W. If you then connect a high resistance passive probe
(like the P6139A) you need to set the input impedance back to
1ĂMW. Step 4 explains how to change the input impedance.
You now need to limit the bandwidth and change the acquisition mode.
3. Press VERTICAL MENU ➞ Bandwidth (main) ➞ 20 MHz (side).
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4. If you need to change the input impedance, press Coupling (main).
Then toggle the side menu selection W to get the correct impedance.
5. Adjust the probe until you see a perfectly flat top square wave on the
display. Figure 3Ć53 shows where the adjustment is located.
Figure 3Ć53:ăP6139A Probe Adjustment
See Probe Selection, on page 3Ć102.
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Probe Selection
The probes included with your digitizing oscilloscope are useful for a wide
variety of tasks. However, for special measurement situations you someĆ
times need different probes. This section helps you select the right probe for
the job.
Once you have decided the type of probe you need, use Table 3Ć6
(page 3Ć107) to determine the specific probe compatible with your
TDS 600A Digitizing Oscilloscope. Or use Table 3Ć7 (page 3Ć108) if you want
to select the probe by application.
There are five major types of probes: passive, active, current, optical, and
timeĆtoĆvoltage probes. Most of these types are discussed here; see your
Tektronix Products Catalog for more information.
Passive voltage probes measure voltage. They employ passive circuit comĆ
ponents such as resistors, capacitors, and inductors. There are three comĆ
mon classes of passive voltage probes:
Passive Voltage
Probes
H
H
H
General purpose (high input resistance)
Low impedance (Z )
O
High voltage
General Purpose (High Input Resistance) Probes
High input resistance probes are considered typical" oscilloscope probes.
The high input resistance of passive probes (typically 10ĂMW) provides
negligible DC loading and makes them a good choice for accurate DC
amplitude measurements.
However, their 8ĂpF to 12ĂpF (over 60ĂpF for 1X) capacitive loading can
distort timing and phase measurements. Use high input resistance passive
probes for measurements involving:
H
H
H
H
Device characterization (above 15 V, thermal drift applications)
Maximum amplitude sensitivity using 1Xhigh impedance
Large voltage range (between 15 and 500 V)
Qualitative or go/noĆgo measurements
Low Impedance (ZO) Probes
Low impedance probes measure frequency more accurately than general
purpose probes, but they make less accurate amplitude measurements.
They offer a higher bandwidth to cost ratio.
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These probes must be terminated in a 50 W scope input. Input capacitance
is much lower than high Z passive probes, typically 1 pF, but input resisĆ
tance is also lower (500 to 5000 W typically). Although that DC loading
degrades amplitude accuracy, the lower input capacitance reduces high
frequency loading to the circuit under test. That makes Z probes ideal for
O
timing and phase measurements when amplitude accuracy is not a major
concern.
Z probes are useful for measurements up to 40 V.
O
High Voltage Probes
High voltage probes have attenuation factors in the 100X to 1000X range.
The considerations that apply to other passive probes apply to high voltage
probes with a few exceptions. Since the voltage range on high voltage
probes varies from 1 kV to 20 kV (DC + peak AC), the probe head design is
mechanically much larger than for a passive probe. High voltage probes
have the added advantage of lower input capacitance (typically 2Ć3 pF).
P6009
P6015A
Figure 3Ć54:ăThe P6009 and P6015A High Voltage Probes
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Probe Selection
Active voltage probes, sometimes called FET" probes, use active circuit
elements such as transistors. There are three classes of active probes:
Active Voltage
Probes
H
H
H
High speed active
Differential active
Fixtured active
Active voltage measuring probes use active circuit elements in the probe
design to process signals from the circuit under test. All active probes
require a source of power for their operation. Power is obtained either from
an external power supply or from the oscilloscope itself. (Your digitizing
oscilloscope powers the optional accessory P6205 probes.)
NOTE
When you connect an active probe to the oscilloscope (such as the
P6205), the input impedance of the oscilloscope automatically
becomes 50 W. If you then connect a passive probe (like the
P6139A) you need toset the input impedance back to1ĂM W. VertiĆ
cal Control on page 3Ć136 explains how to change the input impedĆ
ance.
High Speed Active Probes
Active probes offer low input capacitance (1 to 2ĂpF typical) while maintainĆ
ing the higher input resistance of passive probes (10 kW to 10 MW). Like Z
probes, active probes are useful for making accurate timing and phase
measurements. However, they do not degrade the amplitude accuracy.
Active probes typically have a dynamic range of ±10 to ±15 V.
O
Differential Probes
Differential probes determine the voltage drop between two points in a
circuit under test. Differential probes let you simultaneously measure two
points and to display the difference between the two voltages.
Active differential probes are standĆalone products designed to be used with
50 W inputs. The same characteristics that apply to active probes apply to
active differential probes.
Fixtured Active Probes
In some smallĆgeometry or dense circuitry applications, such as surface
mounted devices (SMD), a handĆheld probe is too big to be practical. You
can instead use fixtured (or probe card mounted) active probes (or buffered
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Probe Selection
amplifiers) to precisely connect your instrument to your deviceĆunderĆtest.
These probes have the same electrical characteristics as high speed, active
probes but use a smaller mechanical design.
Current probes enable you to directly observe and measure current waveĆ
forms, which can be very different from voltage signals. Tektronix current
probes are unique in that they can measure from DC to 1 GHz.
Current Probes
Two types of current probes are available: one that measures AC current
only and AC/DC probes that utilize the Hall effect to accurately measure the
AC and DC components of a signal. ACĆonly current probes use a transĆ
former to convert AC current flux into a voltage signal to the oscilloscope
and have a frequency response froma few hundred Hertz up to 1 GHz.
AC/DC current probes include Hall effect semiconductor devices and proĆ
vide frequency response fromDC to 50 MHz.
Use a current probe by clipping its jaws around the wire carrying the current
that you want to measure. (Unlike an ammeter which you must connect in
series with the circuit.) Because current probes are nonĆinvasive, with loadĆ
ing typically in the milliohm to low W range, they are especially useful where
low loading of the circuit is important. Current probes can also make differĆ
ential measurements by measuring the results of two opposing currents in
two conductors in the jaws of the probe.
Figure 3Ć55:ăA6303 Current Probe Used in the AM 503S Opt. 03
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Probe Selection
Optical probes let you blend the functions of an optical power meter with the
highĆspeed analog waveformanalysis capability of an oscilloscope. You
have the capability of acquiring, displaying, and analyzing optical and elecĆ
trical signals simultaneously.
Optical Probes
Applications include measuring the transient optical properties of lasers,
LEDs, electroĆoptic modulators, and flashlamps. You can also use these
probes in the development, manufacturing, and maintenance of fiber optic
control networks, local area networks (LANs), fiberĆbased systems based on
the FDDI and SONET standard, optical disk devices, and highĆspeed fiber
optic communications systems.
NOTE
When you connect any level 2 probe to the oscilloscope, the input
impedance of the oscilloscope automatically becomes 50 W. If you
then connect a high input impedance passive probe you need to
set the input impedance back to 1ĂMW. Vertical Control, on page
3Ć136, explains how to change the input impedance.
The instantaneous timeĆinterval to voltage converter (TVC) continuously
converts consecutive timing measurements to a timeĆinterval versus time
waveform.
TimeĆtoĆVoltage
Converter
Timing variations typically appear as leftĆtoĆright motion, or jitter, on an
oscilloscope. Time base or trigger holdoff adjustments may improve display
stability, but they do not show timing dynamics. The TVC untangles the
often confusing waveforms and delivers a coherent realĆtime view.
The TVC adds three measurement functions to the voltage versus time
capability of your oscilloscope: time delay versus time, pulseĆwidth versus
time, and period versus time.
3Ć106
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Probe Selection
Table 3Ć6 lists TDS600A compatible probes classified by type.
TableĂ3Ć6:ăTDS 600A Compatible Probes
Probes by Type
Probe Type
Tektronix Model
Description
Passive, high impedance
voltage
P6139A (std.)
P6101A
10X, 500 MHz
1X, 15ĂMHz
Passive, SMD
P6563AS
P6156
20X, 500 MHz
Passive, low impedance Z
10X, 3.5 GHz, for 50 W inputs (1X, 20X, 100X optional)
O
Passive, high voltage
P6009
P6015A
100X,1.5 kV, DC + peak AC
1000X, 20 kV, DC + peak AC
Active, high speed voltage
P6204
DC to 1 GHz FET. DC Offset capability (requires TektroĆ
nix 1103 TekProbe Power Supply for offset capability)
Active, high speed voltage
Active, differential voltage
Active, fixtured voltage
P6205
P6046
DC to 750 MHz FET
1X/10X, DC to 100 MHz
A6501
P6501
Opt. 02
Buffer Amplifier, 1 GHz, 1 MW, 10X
Microprobe with TekProbe Power Cable, 750 MHz,
1MW, 10X
Current
AM 503S
AM 503S
Opt. 03
P6021
AC/DC. Uses A6302 Current Probe.
AC/DC. Uses A6303 Current Probe.
AC. 120 Hz to 60 MHz.
P6022
CTĆ1/CTĆ2
AC. 935 kHz to 120 MHz.
Designed for permanent or semiĆ
ąpermanent inĆcircuit installation
ąCTĆ1: 25ĂkHz to 1ĂGHz, 50W input
ąCTĆ2: 1.2 kHz to 200 MHz, 50W input
Current Transformer for use with
ąAM 503S and P6021. Peak pulse
ą1 kA, 0.5 Hz to 20 MHz with AM 503S
CTĆ4
Logic Word Trigger
P6408
16 channel, one qualifier channel, TTL compatible,
+5 V power supply required
Optical
P6701A
P6703A
P6711
500 to 950 nm, DC to 850 MHz, 1 V/mW
1100 to 1700 nm, DC to 1 GHz, 1 V/mW
500 to 950 nm, DC to 250 MHz, 5 V/mW
1100 to 1700 nm, DC to 300 MHz, 5 V/mW
(OptoĆElectronic Converters)
P6713
TimeĆtoĆVoltage Converter
TVC 501
Time delay, pulse width and period measurements
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Probe Selection
Another way to classify probes is by application. Different applications
demand different probes. Use Table 3Ć7 to select a probe for your applicaĆ
tion.
Probes by
Application
TableĂ3Ć7:ăProbes by Application
TelecommuniĆ Industrial
Consumer/
Computer
Electronics
High Energy
Certification,
cations &
HighĆSpeed
Logic
Electronics
Pulsed Power Regulatory, &
Compliance
Testing
Probe Type
1
1,2
1,2,3
1,2,3
1,2
1,2,3
1,2
Passive, highĆimpedance P6139A
P6139A
P6101A
P6139A
P6101A
P6139A
P6101A
P6139A
P6101A
1
1,2
1
voltage
P6101A
1
1
1
P6563AS
P6563AS
P6563AS
2,3
2,3
2,3
2,3
2,3
Active, highĆspeed digital P6205
P6205
P6205
P6204
P6205
P6205
2,3
voltage
P6204
w/1103 powĆ
2,3
er supply
1,2,3
1,2
1,2,3
Low impedance Z
(low capacitance)
P6156
P6009
P6156
O
1,2,3
1,2
1,2,3
1,2,3
Passive, high voltage
P6009
P6009
P6009
P6009
1,2,3
1,2,3
1,2,3
P6015A
P6015A
P6015A
2,3
2,3
2,3
Active, differential voltage P6046
P6046
P6046
2,3
2,3
2,3
2,3
2,3
Current
AM 503S
P6021
AM 503S
AM 503S
P6021
AM 503S
P6021
AM 503S
1,2
1,2
1,2
1,2
1,2
P6021
P6021
1,2
2,3
CT4
CT1/2
CT4
1,2
2,3
2,3
2,3
Fixtured
A6501
P6501
A6501
P6501
2,3
2,3
Logic Word Trigger
Optical
P6408
P6408
2,3
2,3
2,3
2,3
P6701A
P6703A
P6701A
P6703A
P6711
P6713
P6701A
P6703A
P6711
P6713
2,3
2,3
2,3
2,3
2,3
P6711
P6713
2,3
2,3
2,3
2,3
2,3
2,3
2,3
TimeĆtoĆvoltage converter TVC 501
TVC 501
TVC 501
TVC 501
1
2
3
Qualitative signal evaluation Ċ use when a great deal of accuracy is not required, such as when making go/no go measurements.
Functional testing Ċ use when the device under test is being compared to some standard.
Quantitative Signal Evaluation Ċ use when detailed evaluation is needed.
3Ć108
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Pulse Triggering
Pulse triggering can be very useful. For example, you might be testing a
product with a glitch in the power supply. The glitch appears once a day. So
instead of sitting by and waiting for it to appear, you can use pulse triggering
to automatically capture your data.
There are three classes of pulse triggering: glitch, runt, and width.
H
H
H
A glitch trigger occurs when the trigger source detects a pulse narrower
(or wider) in width than some specified time. It can trigger on glitches of
either polarity. Or you can set the glitch trigger to reject glitches of either
polarity.
A runt trigger occurs when the trigger source detects a short pulse that
crosses one threshold but fails to cross a second threshold before
recrossing the first. You can set the oscilloscope to detect positive or
negative runt pulses.
A width trigger occurs when the trigger source detects a pulse that is
inside or, optionally, outside some specified time range (defined by the
upper limit and lower limit). The oscilloscope can trigger on positive or
negative width pulses.
Figure 3Ć56 shows the pulse trigger readouts. Table 3Ć8, on page 3Ć110,
describes the choices for pulse triggers.
Trigger Class = Runt
Figure 3Ć56:ăPulse Trigger Readouts
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Pulse Triggering
TableĂ3Ć8:ăPulse Trigger Definitions
Definition
Name
Glitch positive
Glitch negative
Glitch either
Triggering occurs if the oscilloscope detects
positive spike widths less than the specified
glitch time.
Triggering occurs if the oscilloscope detects
negative spike widths less than the specified
glitch time.
Triggering occurs if the oscilloscope detects
positive or negative widths less than the speciĆ
fied glitch time.
Runt positive
Triggering occurs if the oscilloscope detects a
positive pulse that crosses one threshold goĆ
ing positive but fails to cross a second threshĆ
old before recrossing the first going negative.
Runt negative
Triggering occurs if the oscilloscope detects a
negative going pulse that crosses one threshĆ
old going negative but fails to cross a second
threshold before recrossing the first going
positive.
Runt either
Triggering occurs if the oscilloscope detects a
positive or negative going pulse that crosses
one threshold but fails to cross a second
threshold before recrossing the first.
Width positive
Width negative
Triggering occurs if the oscilloscope finds a
positive pulse with a width between, or optionĆ
ally outside, the userĆspecified lower and upĆ
per time limits.
Triggering occurs if the oscilloscope finds a
negative pulse with a width between, or opĆ
tionally outside, the userĆspecified lower and
upper time limits.
3Ć110
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Pulse Triggering
The pulse trigger menus let you define the pulse source, select the mode
(auto or normal), and adjust the holdoff. To bring up the Pulse Trigger menu:
Operations Common
to Glitch, Runt, and
Width
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Glitch, Runt, or Width (popĆup) (see Figure 3Ć57).
Figure 3Ć57:ăMain Trigger Menu Ċ Glitch Class
Source
Use this main menu item to specify which channelbecomes the pusl e
trigger source.
Press TRIGGER MENU ➞ Type (main)➞ Pulse (popĆup) ➞
Source (main)➞ Ch1, Ch2, Ch3 (Ax1 on the TDS 620A), orCh4 (Ax2 on
the TDS 620A) (side).
Mode & Holdoff
To change the holdoff time and select the trigger mode:
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞ Mode and
Holdoff (main) ➞ Auto or Normal (side).
H
In Auto mode the oscilloscope acquires a waveform after a specific
time has elapsed even if a trigger does not occur. The amount of
time the oscilloscope waits depends on the time base setting.
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Pulse Triggering
H
In Normal mode the oscilloscope acquires a waveform only if there
is a valid trigger. (You can force a single acquisition by pressing
FORCE TRIGGER.)
2. To change the holdoff time, press Holdoff (side). Use the general purĆ
pose knob or the keypad to enter the value in percent.
When you select the pulse class Glitch, the oscilloscope will trigger on a
pulse narrower (or wider) in width than some specified time.
Glitch Operations
Polarity & Width
This menu item lets you define the glitch in terms of polarity (positive, negaĆ
tive, or either) and width.
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞ Polarity
and Width (main) ➞ Positive, Negative, or Either (side).
H
H
H
Glitch Positive looks at positiveĆgoing pulses.
Glitch Negative looks at negativeĆgoing pulses.
Glitch Either looks at both positive and negative pulses.
2. Press Width (side), and set the glitch width using the general purpose
knob or keypad.
Glitch (Accept or Reject)
To specify whether to trigger on glitches or filter out glitches using the Glitch
main menu item, press TRIGGER MENU ➞ Type (main) ➞ Pulse
(popĆup) ➞ Class (main) ➞ Glitch (popĆup) ➞ Glitch (main) ➞ Accept
Glitch or Reject Glitch (side).
If you choose Accept Glitch, the oscilloscope will trigger only on pulses
narrower than the width you specified. If you select Reject Glitch, it will
trigger only on pulses wider than the specified width.
Level
To set the trigger level with the Level main menu (or the front panel trigger
LEVEL knob), press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Level (main) ➞ Level, Set to TTL, Set to ECL, or Set to 50% (side).
H
H
H
If you select Level, enter a value with the general purpose knob or the
keypad.
If you select Set to TTL, the trigger level is set to the TTL switching
threshold.
If you select Set to ECL, the trigger level is set to the ECL switching
threshold.
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Pulse Triggering
H
If you select Set to 50%, you cause the digitizing oscilloscope to search
for the point halfway between the peaks of the trigger source signal and
set the trigger level to that point.
When you select the pulse class Runt, the oscilloscope will trigger on a
short pulse that crosses one threshold but fails to cross a second threshold
before recrossing the first. To set up runt triggering:
Runt Operation
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Runt (popĆup) ➞ Source (main) ➞ Ch1, Ch2, Ch3
(Ax1 on the TDS 620A), or Ch4 (Ax2 on the TDS 620A) (side). (See
Figure 3Ć58.)
2. Press Polarity (main) ➞ Positive, Negative, or Either (side).
3. Press Thresholds (main), and set the upper and lower thresholds for
runt detection with the side menu selections and the keypad or the
general purpose knob.
Polarity
Use this menu item to specify the direction of the runt pulse.
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Runt (popĆup) ➞ Polarity (main) ➞ Positive, Negative, or
Either (side).
H
H
H
Positive looks for positiveĆgoing runt pulses.
Negative looks for negativeĆgoing runt pulses.
Either looks for both positive and negative runt pulses.
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Pulse Triggering
Selected Trigger Bar at Upper Threshold
Unselected Trigger Bar at Lower
Threshold
Runt Pulse Crosses First Threshold
Only, Recrosses First Threshold Level,
and Triggers Acquisition
Figure 3Ć58:ăMain Trigger MenuĊRunt Class
Thresholds
To set the two threshold levels used in detecting a runt pulse:
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Runt (popĆup) ➞ Thresholds (main).
2. Use the general purpose knob or keypad to set the values for the high
and low thresholds.
Hint: To use the Trigger Bar feature to set the threshold levels on the
pulse train, press DISPLAY ➞ Readout Options (main) ➞ Trigger Bar
Style (side) until Long appears in that menu item.
Note the position of the trigger indicator in Figure 3Ć58. Triggering occurs at
the point the pulse returns over the first (lower) threshold going negative
without crossing the second threshold level (upper). Be aware of the followĆ
ing considerations when using Runt triggering:
H
H
H
When Positive is set in the Polarity side menu, the lower threshold
must be first crossed going positive, then recrossed going negative
without crossing the upper threshold at all.
When Negative is set in the Polarity side menu, the upper threshold
must be first crossed going negative, then recrossed going positive
without crossing the lower threshold at all.
When Either is set in the Polarity side menu, one threshold must be first
crossed going in either direction, then recrossed going in the opposite
direction without crossing the other threshold at all.
3Ć114
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Pulse Triggering
H
Regardless of the polarity setting, triggering occurs at the point the runt
pulse recrosses its first threshold.
When you select the pulse class Width, the oscilloscope will trigger on a
pulse narrower (or wider) than some specified range of time (defined by the
upper limit and lower limit).
Width Operation
Polarity
To define whether the pulses are positive or negative:
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Width (popĆup) ➞ Polarity (main) ➞ Positive or Negative
(side).
Trig When
This menu item lets you establish the range of widths (in units of time) the
trigger source will search for and whether to trigger on pulses that are
outside this range or ones that fall within the range.
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Width (popĆup) ➞ Trig When (main).
2. Press Within Limits (side) if you want the oscilloscope to trigger on
pulses that fall within the specified range. If you want it to trigger on
pulses that are outside the range, then press Out ofLimits (side).
3. To set the range of pulse widths in units of time, press Upper Limit
(side) and Lower Limit (side). Enter the values with the general purpose
knob or keypad. The Upper Limit is the maximum valid pulse width the
trigger source will look for. The Lower Limit is the minimum valid pulse
width. The oscilloscope will always force the Lower Limit to be less than
or equal to the Upper Limit.
Level
To set the trigger level with the Level main menu:
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (popĆup) ➞
Class (main) ➞ Width (popĆup) ➞ Level (main) ➞ Level, Set to TTL, Set to
ECL, or Set to 50% (side).
See Triggering, on page 2Ć13.
For More
Information
See Triggering, on page 3Ć132.
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Remote Communication
You may want to integrate your oscilloscope into a system environment and
remotely control your oscilloscope or exchange measurement or waveform
data with a computer. You can control your oscilloscope remotely via the
IEEE Std 488.2-1987 (GPIB) interface.
GPIB enables data transfers between instruments that support the GPIB
protocols. It provides:
GPIB Protocol
H
H
H
H
Remote instrument control
Bidirectional data transfer
Device compatibility
Status and event reporting
Besides the base protocols, Tektronix has defined codes and formats for
messages to travel over the GPIB. Each device that follows these codes and
formats, such as the TDS 620A, TDS 640A, & TDS 644A, supports standard
commands. Use of instruments that support these commands can greatly
simplify development of GPIB systems.
GPIB Interface Requirements
You can connect GPIB networks in many configurations if you follow these
rules:
H
H
No more than 15 devices, including the controller, can be on a single
bus.
Connect one device load every two meters (about six feet) of cable
length to maintain bus electrical characteristics. (Generally, each instruĆ
ment represents one device load on the bus.)
H
H
H
The total cumulative cable length must not exceed 20 meters (about
65 feet).
At least twoĆthirds of the device loads must be turned on when you use
your network.
There must be only one cable path from each device to each other
device on your network (see Figure 3Ć59), and you must not create loop
configurations.
3Ć116
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Remote Communication
GPIB Device
GPIB Device
GPIB Device
GPIB Device
GPIB Device
GPIB Device
GPIB Device
Figure 3Ć59:ăTypical GPIB Network Configuration
Cables Ċ An IEEE Std 488.1-1987 GPIB cable (available from Tektronix,
part number 012-0991-00) is required to connect two GPIB devices.
Connector Ċ A 24Ćpin GPIB connector is located on the oscilloscope rear
panel. The connector has a DĆtype shell and conforms to IEEE Std
488.1-1987. You can stack GPIB connectors on top of each other (see
Figure 3Ć60).
Figure 3Ć60:ăStacking GPIB Connectors
GPIB Parameters
In the Utility menu you need to define two important GPIB parameters: mode
and address. You need to set the mode to talker/listener, talk only, or off the
bus. You also need to specify the primary communication address.
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Remote Communication
To set up remote communications, ensure that your oscilloscope is physicalĆ
ly cabled to the controller and that the oscilloscope parameters are correctly
set. Plug an IEEE Std 488.2-1987 GPIB cableinto theGPIB connector on
the oscilloscope rear panel and into the GPIB port on your controller (see
FigureĂ3Ć61).
Operation
Rear Panel
Controller
Figure 3Ć61:ăConnecting the Digitizing Oscilloscope to a Controller
To set remote communications parameters:
Press SHIFT UTILITY ➞ System (main) ➞ I/O (popĆup).
Port Selection
Now you need to configure the port to match the controller (see FigĆ
ure 3Ć62).
Press SHIFT UTILITY ➞ System (main) ➞ I/O (popĆup) ➞ Port (main) ➞
GPIB (popĆup) ➞ Configure (main) ➞ Talk/Listen Address, Hardcopy
(Talk Only), or Off Bus (side)
H
H
Choose Talk/Listen Address for normal, controllerĆbased system operaĆ
tion. Usethegeneral purposeknob or thekeypad to definetheaddress.
Use Hardcopy (Talk Only) to usethehardcopy port of your digitizing
oscilloscope. Oncetheport is configured this way, theoscilloscopewill
send the hardcopy data to any listeners on the bus when the HARDCOĆ
PY button is pressed.
If the port is configured any other way and the HARDCOPY button is
pressed, an error will occur and the digitizing oscilloscope will display a
message saying the selected hardcopy port is currently unavailable.
H
Use Off Bus to disconnect thedigitizing oscilloscopefrom thebus.
3Ć118
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Remote Communication
GPIB Configuration Menu
Figure 3Ć62:ăUtility Menu
See Hardcopy, on page 3Ć57.
See the TDS Family Digitizing Oscilloscopes Programmer Manual.
For More
Information
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Saving and Recalling Setups
You may want to save and reuse setups for many reasons. For example,
after changing the setting during the course of an experiment, you may want
to quickly return to your original setup. You can save and recall up to ten
instrument setups from internal oscilloscope memory. The information is
retained even when you turn the oscilloscope off or unplug it.
To save the current setup of the digitizing oscilloscope:
Operation
1. Press SETUP ➞ Save CurrentSetup (main).
Before doing step 2 that follows, note that if you choose a setup
location labeled user, you will overwrite the user setup previously
stored there. You can store setups in setup locations labeled factory
without disturbing previously stored setups.
2. To store to a setup internally, choose one of the ten internal storage
locations from the side menu To Setup 1, To Setup 2, ... (see FigĆ
ure 3Ć63). Now the current setup is stored in that location.
Figure 3Ć63:ăSave/Recall Setup Menu
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Saving and Recalling Settings
To store a setup to disk (optional on the TDS 620A & TDS 640A), press To
File. Then use the general purpose knob to select the exact file from the
resulting scrollbar list. Finally, press the sideĆmenu Save To Selected File to
complete the operation.
Recalling a Setup
To recall a setup stored internally, press SETUP ➞ Recall Saved SetĆ
up (main) ➞ (Recall Setup 1, Recall Setup 2 ... (side).
To recall a setup stored on disk (optional on the TDS 620A & TDS 640A),
press From File. Then use the general purpose knob to select the exact file
from the resulting scrollbar list. Only files with .set extensions will be disĆ
played. Finally, press the sideĆmenu Recall From Selected File to complete
the operation.
Recalling a setup will not change the menu that is currently displayed. If you
recall a setup that is labeled factory in the side menu, you will recall the
factory setup. (The conventional method for recalling the factory setup is
described below.)
Recalling the Factory Setup
To reset your oscilloscope to the factory defaults:
Press SETUP ➞ Recall Factory Setup (main) ➞ OK Confirm Factory Init
(side).
See Factory Initialization Settings, on page AĆ23, for a list of the factory
defaults.
Deleting All Setups and WaveformsĊTek Secure®
Sometimes you might use the digitizing oscilloscope to acquire waveforms
that are confidential. Furthermore, before returning the oscilloscope to
general usage, you might want to remove all such waveforms and any
setups used to acquire them. (Be sure you want to remove all waveforms
and setups, because once they are removed, you cannot retrieve them.) To
use Tek Secure to remove all reference setups and waveforms (does not
affect mass storage disk):
Press SHIFT UTILITY ➞ System (main) ➞ Config (popĆup) ➞ Tek Secure
Erase Memory (main) ➞ OK Erase Ref& Panel Memory (side).
Executing Tek Secure accomplishes the following tasks:
H
H
Replaces all waveforms in reference memories withzero sample values.
Replaces the current front panel setup and all setups stored in setup
memory withthe factory setup.
H
Calculates the checksums of all waveform memory and setup memory
locations to verify successful completion of setup and waveform erasure.
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Saving and Recalling Setups
H
If the checksum calculation is unsuccessful, displays a warning mesĆ
sage; if the checksum calculation is successful, displays a confirmation
message.
Running File Utilities
To run file utilities (optional on the TDS 620A & TDS 640A), see the File
System article on page 3Ć53.
See Tutorial Example 4: Saving Setups, on page 1Ć24.
For More
Information
See Appendix D, Factory Initialization Settings, on page AĆ23.
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Saving and Recalling Waveforms
You can store a waveform in any of the four internal reference memories of
the digitizing oscilloscope. That information is retained even when you turn
the oscilloscope off or unplug it. You can save any combination of different
size waveform records.
The digitizing oscilloscope can display up to 11 waveforms at one time. That
includes waveforms from the four input channels, four reference waveforms,
and three math waveforms.
You will find saving waveforms useful when working with many waveforms
and channels. If you have more waveforms than you can display, you can
save one of the waveforms and then stop acquiring it. That lets you display
another waveform without forcing you to loose the first one.
To save a waveform, do the following steps:
Operation
1. Select the channel that has the waveform you want to save.
Before doing step 2 that follows, note that if you choose a reference
memory location labeled active (see Figure 3Ć64), you will overwrite
the waveform that was previously stored there. You can store waveĆ
forms in reference locations labeled empty without disturbing preĆ
viously stored waveforms.
2. To store a waveform internally, press save/recall WAVEFORM ➞ Save
Waveform (main) ➞ Ref1, Ref2, Ref3, Ref4, or File (side).
To store a waveform to disk(optional on the TDS 620A & TDS 640A),
press ToFile . Then use the general purpose knob to select the exact file
from the resulting scrollbar list. Finally, press the sideĆmenu Save To
Selected File to complete the operation.
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Saving and Recalling Waveforms
Figure 3Ć64:ăSave Waveform Menu
Deleting Waveforms
You can choose the Delete Refs main menu item andthen select the referĆ
ences you no longer needfrom the side menu ( Delete Ref1, Delete Ref2,
Delete Ref3, Delete Ref4, or Delete All Refs).
Deleting All Waveforms and Setups
You can remove all storedreference waveforms andsetups using the feature
called Tek Secure. It is described under Saving and Recalling Setups. See
Deleting All Setups andWaveforms" on page 3Ć121.
Displaying a Saved Waveform
To display a waveform in internal reference memory:
Press MORE ➞ Ref1, Ref2, Ref3, or Ref4 (main).
Note that in Figure 3Ć65, the main menu items Ref2, Ref3, and Ref4 appear
shaded while Ref1 does not. References that are empty appear shaded in
the More main menu.
Recalling a Waveform From Disk
To recall a waveform from disk (optional on the TDS 620A & TDS 640A) to
an internal reference memory, press save/recall WAVEFORM ➞ Recall Wfm
To Ref. Then use the general purpose knob to select the exact file from the
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Saving and Recalling Waveforms
resulting scrollbar list. Only files with .WFM extensions are displayed. Finally,
press from the sideĆmenu To Ref1, To Ref2, To Ref3, or To Ref4 choices to
complete the operation.
Figure 3Ć65:ăMore Menu
Autosave (TDS 640A and 644A only)
To use autosave, press
Autosave (main) ➞ Autosave Single Seq ON (side).
Also turnon Single Acquisition Sequence inthe Acquire menu
(see page 3Ć6).
To disable this feature, simply press
Autosave (main) ➞ Autosave Single Seq OFF (side).
If you enable both autosave and single sequence, the TDS will save all live
channels to reference waveforms at the completion of each single sequence
event. All previous reference waveform data will be erased.
Running File Utilities
To runfile utilities (optional onthe TDS 620A & TDS 640A), see the File
System article onpage 3Ć53.
See Selecting Channels, onpage 3Ć126.
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Selecting Channels
The selected channel is the channel that the digitizing oscilloscope applies
all waveformĆspecific activities to (such as measurements or vertical scale
and position).
The channel readout shows the selected channel in inverse video in the
lower left corner of the display. The channel reference indicator for the
selected channel appears along the left side of the display. See Figure 3Ć66.
Channel Readout
and Reference
Indicator
Channel Reference
Indicator
Channel Readout
Figure 3Ć66:ăThe Channel Readout
Selecting channelson the TDS 600A seriesoscilloscopesisstraightforward
and easy.
Channel Selection
Buttons
The channel selection buttonsare on the right of the display and are labeled
CH 1, CH 2, CH 3(AUX 1on the TDS 620A),CH 4(AUX 2on the
TDS 620A), andMORE. They determine which channel isselected. The
MORE button allows you to select internally stored Math and Ref waveforms
for display and manipulation.
The selected channel is indicated by the lighted LED above each button.
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Selecting Channels
To selecting a channel:
Operation
Pressing CH 1, CH 2, CH 3 (AUX 1 on theTDS 620A), or CH 4(AUX 2 on
the TDS 620A) turns the channel on if it is not already on.
You do not use the channel selection buttons when triggering. Instead you
select the trigger source in the Main Trigger menu or Delayed Trigger menu.
Removing Waveforms From the Display
The WAVEFORM OFF button turns OFF the display of the selected channel
waveform. It will also remove from the display any automated measurements
being made on that waveform.
When you turn off a waveform, the digitizing oscilloscope automatically
selects the next highest priority waveform. Figure 3Ć67 shows how the
oscilloscope prioritizes waveforms.
ă1. CH1
ă2. CH2
ă3. CH3 (AUX 1 on theTDS 620A)
ă4. CH4 (AUX 2 on theTDS 620A)
ă5. MATH1
ă6. MATH2
ă7. MATH3
ă8. REF1
ă9. REF2
10. REF3
11. REF4
Figure 3Ć67:ăWaveform Selection Priority
If you areturning off morethan onewaveform and you start by turning off a
channel waveform, all channels will be turned off before going to the MORE
waveforms. If you start by turning off the MORE waveforms, all the MORE
waveforms will be turned off before going to the channel waveforms.
If you turn off a channel that is a trigger source, it continues to be the trigger
source even though the waveform is not displayed.
See Saving and Recalling Waveforms, on page3Ć123.
For More
Information
See Waveform Math, on page3Ć148.
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Signal Path Compensation
This oscilloscope lets you compensate the internal signal path used to
acquire the waveforms you acquire and measure. By executing the signal
path compensation feature (SPC), you can optimize the oscilloscope capaĆ
bility to make accurate measurements based on the ambient temperature.
Run an SPC anytime you wish to ensure that the measurements you make
are made with the most accuracy possible. You should also run an SPC if
the temperature has changed more than 5_ C since the last SPC was perĆ
formed.
NOTE
When making measurements at volts/division settings less than or
equal to 5 mV, you should run SPC at least once per week. Failure
to do so may result in the oscilloscope not meeting warranted
performance levels at those volts/div settings. (Warranted characĆ
teristics are listed in the Performance Verification manual.)
1. Power on the digitizing oscilloscope and allow a 20 minute warmĆup
before doing this procedure.
Operation
2. Disconnect any input signals you may have connected from all four
input channels.
When doing steps 3 and 4, do not turn off the oscilloscope until
signalĆpath compensation completes. Ifyou interrupt (or lose) power
to the instrument while signalĆpath compensation is running, a
message is logged in the oscilloscope error log. Ifsuch a case
occurs, rerun signalĆpath compensation.
3. Press SHIFT UTILITY ➞ System (main) ➞ Cal (popĆup) ➞ Signal
Path (main) ➞ OK Compensate Signal Paths (side).
4. Wait for signal path compensation to complete (one to three minutes).
While it progresses, a clock" icon (shown at left) is displayed onĆ
screen. When compensation completes, the status message will be
updated to Pass or Fail in the main menu.
5. Verify the word Pass appears under Signal Path in the main menu. (See
Figure 3Ć68.)
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Signal Path Compensation
Figure 3Ć68:ăPerforming a Signal Path Compensation
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Status
The Status menu lets you see information about the oscilloscope state.
To operate the Status menu:
Operation
Press SHIFT STATUS ➞ Status (main) ➞ System, Display, Trigger,
Waveforms, or I/O (side). Note: some oscilloscopes do not have a main
Status menu. On these instruments, press SHIFT STATUS ➞ System,
Display, Trigger, Waveforms, or I/O (side).
H
System displays information about the Horizontal, Zoom, Acquisition,
Measure, and Hardcopy systems (Figure 3Ć69). This display also tells
you the firmware version.
H
Display provides parameter information about the display and color
systems.
H
H
Trigger displays parameter information about the triggers.
Waveforms displays information about the various waveforms, including
live, math, and reference.
H
I/O displays information about the I/O port(s).
Firmware Version
Figure 3Ć69:ăStatus Menu Ċ System
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Status
To display the banner (firmware version, options, copyright, and patents):
Banner
NOTE
Some TDS 644A oscilloscopes do not have a Status main menu
with a banner. However, all instruments display the banner briefly at
powerĆon.
Press SHIFT STATUS ➞ Banner (main) (see Figure 3Ć70).
Figure 3Ć70:ăBanner Display
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Triggering
Triggers determine when the digitizing oscilloscope starts acquiring and
displaying a waveform. The TDS 600A has four types of trigger: edge, logic,
pulse, and, with option 5, video.
Although these triggers are unique, they have some common characteristics
that can be defined and modified using the Trigger menu, buttons, and
knob. This article discusses these common characteristics.
To learn about the general concept of triggering, see Triggering in the OperĆ
ating Basics section. To learn more about using specific triggers and using
the delayed trigger system, see For More Information on page 3Ć135.
The trigger buttons and knob let you quickly adjust the trigger level or force
a trigger (see Figure 3Ć71).
Trigger Buttonand
Knobs
Trigger Status Lights
Figure 3Ć71:ăTRIGGER Controls and Status Lights
MAIN LEVEL Knob
The MAIN LEVEL knob lets you manually change the trigger level when
triggering in Edge mode or certain threshold levels when triggering in Logic
or Pulse modes. It adjusts the trigger level (or threshold level) instantaĆ
neously no matter what menu, if any, is displayed.
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Triggering
To Set to 50%
You can quickly obtain an edge or pulse trigger (except for the Runt class)
by pressing SETLEVEL TO 50%. The oscilloscope sets the trigger level to
the halfway point between the peaks of the trigger signal.
You can also set the level to 50% in the Trigger menu under the main menu
item Level if Edge or Pulse (except for Runt class) is selected.
Note that the MAIN LEVEL knob andmenu items apply only to the main
trigger level. To modify the delayed trigger level, use the Level item in the
DelayedTrigger menu.
Force Trigger
By pressing the FORCE TRIG front panel button, you can force the oscilloĆ
scope to immediately start acquiring a waveform record even without a
trigger event. Forcing a trigger is useful when in normal trigger mode and
the input signal is not supplying a validtrigger. By pressing FORCE TRIG,
you can quickly confirm that there is a signal present for the oscilloscope to
acquire. Once that is established, you can determine how to trigger on it
(press SETLEVEL TO 50% , check trigger source setting, etc.).
The oscilloscope recognizes andacts upon FORCE TRIG even when you
press it before the endof pretrigger holdoff. However, the button has no
effect if the acquisition system is stopped.
Single Trigger
If your goal is to act on the next validtrigger event andthen stop, press
SHIFTFORCE TRIG . Now you can initiate the single sequence of acquisiĆ
tions by pressing the RUN/STOP button.
To leave Single Trig mode, press SHIFTACQUIRE MENU ➞ Stop AfĆ
ter (main)➞ RUN/STOP Button Only (side).
See the description under Stop After" on page 3Ć6 for further discussion of
single sequence acquisitions.
The digitizing oscilloscope has display readouts and status lights dedicated
to monitoring the trigger circuitry.
Readouts
Trigger Status Lights
There are three status lights in the Trigger control area (Figure 3Ć71) indicatĆ
ing the state of the trigger circuitry. The lights are labeled TRIG'D, READY,
and ARM.
H
When TRIG'D is lighted, it means the digitizing oscilloscope has recogĆ
nizeda validtrigger andis filling the posttrigger portion of the waveform.
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Triggering
H
When READY is lighted, it means the digitizing oscilloscope can accept
a valid trigger event, and the digitizing oscilloscope is waiting for that
event to occur.
H
H
When ARM is lighted, it means the trigger circuitry is filling the pretrigger
portion of the waveform record.
When both TRIG'D and READY are lighted, it means the digitizing
oscilloscope has recognized a valid main trigger and is waiting for a
delayed trigger. When the digitizing oscilloscope recognizes a delayed
trigger, it will fill in the posttrigger portion of the delayed waveform.
H
When ARM, TRIG'D, and READY are all off, the digitizer is stopped.
Trigger Display Readout
At the bottom of the display, the Trigger readout shows some of the key
trigger parameters (Figure 3Ć72). The readouts are different for edge, logic
and pulse triggers.
Main Trigger
Source = Ch 1
Main Time Base Time/Div
Main Time Base
Main Trigger Slope =
Rising Edge
Main Trigger
Level
Figure 3Ć72:ăExample Trigger Readouts
The record view at the top of the display shows the location of the trigger
signal in the waveform record and with respect to the display (see FigĆ
ure 3Ć73).
Trigger Position and Level Indicators
In addition to the numerical readouts of trigger level, there are also graphic
indicators of trigger position and level which youcan optionally display.
These indicators are the trigger point indicator, the long trigger level bar, and
the short trigger level bar. Figure 3Ć73 shows the trigger point indicator and
shortĆstyle trigger level bar.
The trigger point indicator shows position. It can be positioned horizontally
off screen, especially with long record length settings. The trigger level bar
shows only the trigger level. It remains on screen, regardless of the horizonĆ
tal position, as long as the channel providing the trigger source is displayed.
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Triggering
Trigger Position Relative to the
Display and Waveform Record
Trigger Point Indicator Indicating
the Trigger Position on the
Waveform Record
Trigger Bar Indicating the Trigger
Level on the Waveform Record
Figure 3Ć73:ăRecord View, Trigger Position, and Trigger Level Bar Readouts
Both the trigger point indicator and level bar are displayed fromthe Display
menu. See Display Readout on page 3Ć28 for more information.
Each trigger type (edge, logic, and pulse) has its own main trigger menu,
which is described in a separate part of this section (see For More InformaĆ
tion).
Trigger Menu
To select the trigger type, press TRIGGER MENU ➞ Type (main) ➞ Edge,
Logic, or Pulse (popĆup).
See Delay Triggering, on page 3Ć20.
See Edge Triggering, on page 3Ć32.
See Logic Triggering, on page 3Ć75.
See Pulse Triggering, on page 3Ć109.
See Triggering, on page 2Ć13.
For More
Information
See the Option 05 Video Trigger Interface Instruction Manual, Tektronix part
number 070Ć8748ĆXX.
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Vertical Control
You can control the vertical position and scale of the selected waveform
using the vertical menu and knobs.
By changing the vertical scale, you can focus on a particular portion of a
waveform. By adjusting the vertical position, you can move the waveform up
or down on the display. That is particularly useful when you are comparing
two or more waveforms.
Vertical Knobs
To change the vertical scale and position, use the vertical POSITION and
vertical SCALE knobs. The vertical controls only affect the selected waveĆ
form.
The POSITION knob simply adds screen divisions to the reference point of
the selected waveform. Adding divisions moves the waveform up and subĆ
tracting them moves the waveform down. You also can adjust the waveform
position using the offset option in the Vertical menu (discussed later in this
article).
If you want the POSITION knob to move faster, press the SHIFT button.
When the light above the SHIFT button is on and the display says Coarse
Knobs in the upper right corner, the POSITION knob speeds up significantĆ
ly.
The Vertical readout at the lower part of the display shows each displayed
channel (the selected channel is in inverse video), and its volts/division
setting (see Figure 3Ć74).
Vertical Readouts
Vertical Menu
The Vertical menu (Figure 3Ć74) lets you select the coupling, bandwidth, and
offset for the selected waveform. It also lets you numerically change the
position or scale instead of using the vertical knobs.
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Vertical Control
Vertical Readout
Figure 3Ć74:ăVertical Readouts and Channel Menu
Coupling
To choose the type of coupling for attaching the input signal to the vertical
attenuator for the selected channel and to set its input impedance:
Press VERTICAL MENU ➞ Coupling (main) ➞ DC, AC, GND, or W (side).
H
H
H
DC coupling shows both the AC and DC components of an input signal.
AC coupling shows only the alternating components of an input signal.
Ground (GND) coupling disconnects the input signal from the acquisiĆ
tion.
H
Input impedance lets you select either 1ĂMW or 50 WĂ impedance.
NOTE
If you select 50 W impedance with AC coupling, the digitizing
oscilloscope will not accurately display frequencies under 200 kHz.
Also, when you connect an active probe to the oscilloscope (such
as the P6205), the input impedance of the oscilloscope automatiĆ
cally becomes 50 W. If you then connect a passive probe (like the
P6139A), you need toset the input impedance back to1ĂM W.
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Vertical Control
Bandwidth
To eliminate the higher frequency components, change the bandwidth of the
selected channel:
Press VERTICAL MENU ➞ Bandwidth (main) ➞ Full, 100 MHz, or 20ĂMHz
(side).
Fine Scale
Press VERTICAL MENU ➞ Fine Scale (main) to make fine adjustments to
the vertical scale using the general purpose knob or the keypad.
Position
Press VERTICAL MENU ➞ Position (main) to let the general purpose knob
control the vertical position. Press Set to 0 divs (side) if you want to reset
the reference point of the selected waveform to the center of the display.
Offset
Offset lets you subtract DC bias from the waveform, so the oscilloscope can
acquire the exact part of the waveform you are interested in.
Offset is useful when you want to examine a waveform with a DC bias. For
example, you might be trying to lookat a small ripple on a power supply
output. It may be a 100 mV ripple on top of a 15 V supply. Using offset, you
can display the ripple and scale it to meet your needs.
To use offset, press VERTICAL MENU ➞ Offset (main). Use the general
purpose knob to control the vertical offset. Press Set to 0 V (side) if you
want to reset the offset to zero.
See Acquisition, on page 2Ć19.
For More
Information
See Scaling and Positioning Waveforms, on page 2Ć22.
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Waveform Differentiation
Advanced DSP Math (optional on TDS 620A & TDS 640A), provides waveĆ
form differentiation that allows you to display a derivative math waveform
that indicates the instantaneous rate of change of the waveform acquired.
Such waveforms are used in the measurement of slew rate of amplifiers and
in educational applications. You can store and display a derivative math
waveform in a reference memory, then use it as a source for another derivaĆ
tive waveform. The result is the second derivative of the waveform that was
first differentiated.
The math waveform, derived from the sampled waveform, is computed
based on the followingequation:
Description
1
T
Yn + (X(n)1) * Xn)
Where:
X is the source waveform
Y is the derivative math waveform
T is the time between samples
Since the resultant math waveform is a derivative waveform, its vertical scale
is in volts/second (its horizontal scale is in seconds). The source signal is
differentiated over its entire record length; therefore, the math waveform
record length equals that of the source waveform.
To obtain a derivative math waveform:
Operation
1. Connect the waveform to the desired channel input and select that
channel.
2. Adjust the vertical and horizontal scales and trigger the display (or press
AUTOSET).
3. Press MORE ➞ Math1, Math2, or Math3 (main) ➞ Change Math
Definition (side) ➞ Single Wfm Math (main). See Figure 3Ć21.
4. Press Set Single Source to (side). Repeatedly press the same button
(or use the general purpose knob) until the channel source selected in
step 1 appears in the menu label.
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Waveform Differentation
Derivative Math
Waveform
Source
Waveform
Figure 3Ć75:ăDerivative MathWaveform
5. Press Set Function to (side). Repeatedly press the same button (or use
the general purpose knob) until diff appears in the menu label.
6. Press OK Create MathWfm (side) to display the derivative of the waveĆ
form you input in step 1.
You should now have your derivative math waveform on screen. Use the
Vertical SCALE and POSITION knobs to size and position your waveĆ
form as you require.
Automated Measurements of a Derivative Waveform
Once you have displayed your derivative math waveform, you can use
automated measurements to make various parameter measurements. Do
the following steps to display automated measurements of the waveform:
1. Be sure MORE is selected in the channel selection buttons and that the
differentiated math waveform is selected in the More main menu.
2. Press MEASURE ➞ Select Measrmnt (main).
3. Select up to four measurements in the side menu (see Figure 3Ć76).
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WaveformDifferentation
Figure 3Ć76:ăPeakĆPeak Amplitude Measurement of a Derivative
Waveform
Cursor Measurement of a Derivative Waveform
You can also use cursors to measure derivative waveforms. Use the same
procedure as is found under Waveform Integration on page 3Ć144. When
using that procedure, note that the amplitude measurements on a derivative
waveform will be in volts per second rather than in voltĆseconds as is indiĆ
cated for the integral waveform measured in the procedure.
When creating differentiated math waveforms from live channel waveforms,
consider the following topics.
Usage
Considerations
Offset, Position, and Scale
Note the following tips for obtaining a good display:
H
You should scale and position the source waveform so it is contained on
screen. (Off screen waveforms may be clipped, resulting in errors in the
derivative waveform).
H
You can use vertical position and vertical offset to position your source
waveform. The vertical position and vertical offset will not affect your
derivative waveform unless you position the source waveform off screen
so itis clipped.
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Waveform Differentation
H
When using the vertical scale knob to scale the source waveform, note
that it also scales your derivative waveform.
Because of the method the oscilloscope uses to scale the source waveform
before differentiating that waveform, the derivative math waveform may be
too large vertically to fit on screen Ċ even if the source waveform is only a
few divisions on screen. You can use Zoom to reduce the size of the waveĆ
form on screen (see Zoom that follows), but if your waveform is clipped
before zooming, it will still be clipped after it is zoomed.
If your math waveform is a narrow differentiated pulse, it may not appear to
be clipped when viewed on screen. You can detect if your derivative math
waveform is clipped by expanding it horizontally using Zoom so you can see
the clipped portion. Also, the automated measurement PkĆPk will display a
clipping error message if turned on (see Automated Measurements of a
Derivative Waveform on page 3Ć140).
If your derivative waveform is clipped, try either of the following methods to
eliminate clipping:
H
H
Reduce the size of the source waveform on screen. (Select the source
channel and use the vertical SCALE knob.)
Expand the waveform horizontally on screen. (Select the source channel
and increase the horizontal scale using the horizontal SCALE knob.) For
instance, if you display the source waveform illustrated in Figure 3Ć75 on
page 3Ć140 so its rising and falling edges are displayed over more
horizontal divisions, the amplitude of the corresponding derivative pulse
will decrease.
Whichever method you use, be sure Zoom is off and the zoom factors are
reset (see Zoom below).
Zoom
Once you have your waveform optimally displayed, you can also magnify (or
contract) it vertically and horizontally to inspect any feature. Just be sure the
differentiated waveform is the selected waveform. (Press MORE, then select
the differentiated waveform in the More main menu. Then use the Vertical
and Horizontal SCALE knob to adjust the math waveform size.)
If you wish to see the zoom factor (2X, 5X, etc.), you need to turn zoom on:
press ZOOM ➞ ON (side). The vertical and horizontal zoom factors appear
on screen.
Whether zoom is on or off, you can press ResetZoom Factors (side) to
return the zoomed derivative waveform to no magnification.
See Waveform Integration, on page 3Ć143.
See Fast Fourier Transforms, on page 3Ć36.
See Waveform Math, on page 3Ć148.
For More
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Waveform Integration
Advanced DSP Math (optional on TDS 620A & TDS 640A), provides waveĆ
form integration that allows you to display an integral math waveform that is
an integrated version of the acquired waveform. Such waveforms find use in
the following applications:
H
H
Measuring of power and energy, such as in switching power supplies
Characterizing mechanical transducers, as when integrating the output
of an accelerometer to obtain velocity
The integral math waveform, derived from the sampled waveform, is comĆ
puted based on the following equation:
Description
n
x(i) ) x(i * 1)
i + 1
x(i) is the source waveform
y(n) + scale
T
S
2
Where:
y(n) is a point in the integral math waveform
scale is the output scale factor
T is the time between samples
Since the resultant math waveform is an integral waveform, its vertical scale
is in voltĆseconds (its horizontal scale is in seconds). The source signal is
integrated over its entire record length; therefore, the math waveform record
length equals that of the source waveform.
To obtain an integral math waveform:
Operation
1. Connect the waveform to the desired channel input and select that
channel.
2. Adjust the vertical and horizontal scales and trigger the display (or press
AUTOSET).
3. Press MORE ➞ Math1, Math2, or Math3 (main) ➞ Change Math
waveform definition (side) ➞ Single Wfm Math (main).
4. Press Set Single Source to (side). Repeatedly press the same button
until the channel source selected in step 1 appears in the menu label.
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Waveform Integration
5. Press Set Function to (side). Repeatedly press the same button until
intg appears in the menu label.
6. Press OK Create Math Waveform (side) to turn on the integralmath
waveform.
You should now have your integral math waveform on screen. See
Figure 3Ć77. Use the Vertical SCALE and POSITION knobs to size and
position your waveform as you require.
Integral Math
Waveform
Source
Waveform
Figure 3Ć77:ăIntegral Math Waveform
Cursor Measurements of an Integral Waveform
Once you have displayed your integrated math waveform, use cursors to
measure its voltage over time.
1. Be sure MORE is selected (illuminated) in the channel selection buttons
and that the integrated math waveform is selected in the More main
menu.
2. Press CURSOR ➞ Mode (main) ➞ Independent (side) ➞ FuncĆ
tion (main) ➞ H Bars (side).
3. Use the general purpose knob to align the selected cursor (solid) to the
top (or to any amplitude level you choose).
4. Press SELECT to select the other cursor.
5. Use the general purpose knob to align the selected cursor (to the botĆ
tom (or to any amplitude level you choose).
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Waveform Integration
6. Read the integrated voltage over time between the cursors in voltĆ
seconds fromthe D: readout. Read the integrated voltage over time
between the selected cursor and the reference indicator of the math
waveformfromthe @: readout. See Figure 3Ć78.
Integral Math
Waveform
Source
Waveform
Figure 3Ć78:ăH Bars Cursors Measure an Integral Math Waveform
7. Press Function (main) ➞ V Bars (side). Use the general purpose knob
to align one of the two vertical cursors to a point of interest along the
horizontal axis of the waveform.
8. Press SELECT to select the alternate cursor.
9. Align the alternate cursor to another point of interest on the math waveĆ
form.
10. Read the time difference between the cursors from the D: readout. Read
the time difference between the selected cursor and the trigger point for
the source waveformfromthe @: readout.
11. Press Function (main) ➞ Paired (side).
12. Use the technique just outlined to place the long vertical bar of each
paired cursor to the points along the horizontal axis you are interested
in.
13. Read the following values fromthe cursor readouts:
H
Read the integrated voltage over time between the Xs of both paired
cursors in voltĆseconds fromthe D: readout.
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Waveform Integration
H
H
Read the integrated voltage over time between the X of the selected
cursor and the reference indicator of the math waveform from the
@: readout.
Read the time difference between the long vertical bars of the paired
cursors from the D: readout.
Automated Measurements of a Integral Waveform
You can also use automated measurements to measure integral math waveĆ
forms. Use the same procedure as is found under Waveform Differentiation
on page 3Ć140. When using that procedure, note that your measurements
on an integral waveform will be in voltĆseconds rather than in volts per
second as is indicated for the differential waveform measured in the proceĆ
dure.
When creating integrated math waveforms from live channel waveforms,
consider the following topics.
Usage
Considerations
Offset, Position, and Scale
Note the following requirements for obtaining a good display:
H
You should scale and position the source waveform so it is contained on
screen. (Off screen waveforms may be clipped, which will result in errors
in the integral waveform).
H
You can use vertical position and vertical offset to position your source
waveform. The vertical position and vertical offset will not affect your
integral waveform unless you position the source waveform off screen
so it is clipped.
H
When using the vertical scale knob to scale the source waveform, note
that it also scales your integral waveform.
DC Offset
The source waveforms that you connect to the oscilloscope often have a DC
offset component. The oscilloscope integrates this offset along with the time
varying portions of your waveform. Even a few divisions of offset in the
source waveform may be enough to ensure that the integral waveform
saturates (clips), especially with long record lengths.
You may be able to avoid saturating your integral waveform if you choose a
shorter record length. (Press HORIZONTAL MENU ➞ Record
Length (main).) Reducing the sample rate (use the HORIZONTAL SCALE
knob) with the source channel selected might also prevent clipping. You can
also select AC coupling (on TDS models so equipped) in the vertical menu
of the source waveform or otherwise DC filter it before applying it to the
oscilloscope input.
Reference
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Waveform Integration
Zoom
Once you have your waveform optimally displayed, you may magnify (or
reduce) it vertically and horizontally to inspect any feature you desire. Just
be sure the integrated waveform is the selected waveform. (Press MORE,
then select the integrated waveform in the More main menu. Then use the
Vertical and Horizontal SCALE knobs to adjust the math waveform size.)
Ifyou wish to see the zoom factor (2X, 5X, etc.) you need to turn Zoom on:
press ZOOM ➞ On (side). The vertical and horizontal zoom factors appear
on screen.
Whether Zoom is on or off, you can press Reset Zoom Factors (side) to
return the zoomed integral waveform to no magnification.
See Waveform Differentiation, on page 3Ć139.
See Fast Fourier Transforms, on page 3Ć36.
See Waveform Math, on page 3Ć148.
For More
Information
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Waveform Math
You can mathematically manipulate your waveforms. For example, you
might have a waveform clouded by background noise. You can obtain a
cleaner waveform by subtracting the background noise from your original
waveform.
This section describes the invert, add, subtract, divide, and multiply waveĆ
form math features. If your oscilloscope is equipped with Advanced DSP
Math (optional on TDS 620A & TDS 640A), see Fast Fourier Transforms on
page 3Ć36, Waveform Differentiation on page 3Ć139, and Waveform IntegraĆ
tion on page 3Ć143.
To perform waveform math, press the MORE button to bring up the More
menu (Figure 3Ć79). The More menu allows you to display, define, and
manipulate three math functions.
Operation
Figure 3Ć79:ăMore Menu
Math1, Math2, and Math3
1. Press MORE ➞ Math1, Math2, or Math3 (main) to select the waveform
that you want to display or change.
3Ć148
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Waveform Math
NOTE
If your digitizing oscilloscope is equipped with Advanced DSP Math
(optionalon TDS 620A & TDS 640A), the menu itemFFT will be at
the same brightness as the menu items Single Wfm Math and
Dual Wfm Math; otherwise, FFT will be dimmed. See pages 3Ć36,
3Ć139, and 3Ć143 for information on FFTs and other advanced math
waveforms.
2. Press Average (side) and enter a value with the general purpose knob
or the keypad to take an average of multiple acquisitions. Press No
Extended Processing (side) to perform math operations only on one
acquisition.
3. If desired, turn on or turn off math averaging. To turn on math averaging,
press Average (side) and turn the general purpose knob (or use the
keypad) to enter the number of times to successively average the math
waveform before completing an acquisition. Press No Extended ProĆ
cessing (side) to turn off math averaging.
4. Press Change Math waveform definition (side) ➞ FFT (if your oscilloĆ
scope contains Advanced DSP Math), Single Wfm Math, or Dual Wfm
Math (main) to alter the present math waveform definition (see FigĆ
ure 3Ć80).
The single and dual waveform operations are described separately in
the following topics. For descriptions of Advanced DSP Math, see Fast
Fourier Transforms on page 3Ć36, Waveform Differentiation on
page 3Ć139, and Waveform Integration on 3Ć143.
Single Wfm Math
1. Press MORE ➞ Math1, Math2, or Math3 (main) ➞ Change Math
waveform definition (side) ➞ Single Wfm Math (main). Press Set
Function to (side) to select inv (invert), intg (if your oscilloscope conĆ
tains Advanced DSP Math), or diff (if your oscilloscope contains AdĆ
vanced DSP Math). Waveform integration (intg) is described on
page 3Ć143, and waveform differentiation (diff) is described on
page 3Ć139.
2. To define the source waveform, press Set Single Source to (side).
3. When you are ready to perform the function, press OK Create Math
Wfm (side).
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Waveform Math
Figure 3Ć80:ăDual Waveform Math Main and Side Menus
Dual Wfm Math
1. Select the sources with MORE ➞ Math1, Math2, or Math3 (main) ➞
Change Math waveform definition (side) ➞ Dual Wfm Math (main) ➞
Set 1st Source to and Set 2nd Source to (side). Enter the sources by
repeatedly pressing the appropriate channel selection button.
2. To enter the math operator, press Set operator to (side) to cycle
through the choices. Supported operators are +, -, * and /.
3. Press OK Create Math Wfm (side) to perform the function.
NOTE
If you select *, for multiply, in step 2, the cursor feature will meaĆ
sure amplitude in the units volts squared VV rather than in volts V.
If your oscilloscope is equipped with Advanced DSP Math, you can also
create integrated, differentiated, and Fast Fourier Transform waveforms. See
Fast Fourier Transforms onpage 3Ć36, Waveform Integration onpage 3Ć139,
and Waveform Differentiation onpage 3Ć143.
For More
Information
3Ć150
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Zoom
At times, you may want to expand or compress a waveform on the display
without changing the acquisition parameters. You can do that with the zoom
feature.
When you zoom in on a waveform on the display, you expand a portion of
the waveform. The digitizing oscilloscope may need to show more points for
that portion than it has acquired. Ifit needs to do this, it interpolates. The
instrument can interpolate in either oftwo ways: linear or sin(x)/x. (The
interpolation methods are described on page 2Ć20.)
Zoom and
Interpolation
When you zoom, the display redraws the waveforms using the interpolation
method you selected in the Display menu (linear interpolation or sin(x)/x). If
you selected sin(x)/x (the default), it may introduce some overshoot or
undershoot to the waveform edges. If that happens, change the interpolaĆ
tion method to linear, following the instructions on page 3Ć152.
To differentiate between the real and interpolated samples, set the display
style to Intensified Samples.
When you turn on the zoom feature, the vertical and horizontal scale and
vertical position knobs now control the displayed size and position ofwaveĆ
forms, allowing them to be expanded and repositioned on screen. They
cease to affect waveform acquisition, but you can alter acquisition by using
the corresponding menu items. Zoom mode does not change the way
horizontal position operates.
Operation
To use zoom, do the following steps:
1. Press ZOOM ➞ ON (side). The ZOOM frontĆpanel button should light
up.
2. Choose which waveforms to zoom by repeatedly pressing Horizontal
Lock (side).
H
H
None Ċ only the waveform currently selected can be magnified and
positioned horizontally (Figure 3Ć81).
Live Ċ all channels (including AUX channels for the TDS 620A) can
be magnified and positioned horizontally at the same time. (WaveĆ
forms displayed from an input channel are live; math and reference
waveforms are not live.)
H
All Ċ all waveforms displayed (channels, math, and/or reference)
can be magnified and positioned horizontally at the same time.
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Zoom
NOTE
Although zoom must be turned on to control which waveforms
zoom affects, the setting for Horizontal Lock affects which waveĆ
forms the horizontal control positions whether zoom is on or off.
The rules for the three settings are listed in step 2.
Only the selected
waveform (the top one)
changes size.
Figure 3Ć81:ăZoom Mode with Horizontal Lock Set to None
Setting Interpolation
To change the interpolation method used:
Press DISPLAY ➞ Filter (main) ➞ Sin(x)/x Interpolation or Linear InterĆ
polation (side).
3Ć152
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Zoom
Reset Zoom
To reset all zoom factors to their defaults (see Table 3Ć9), press ZOOM ➞
Reset Zoom Factors (side).
TableĂ3Ć9:ăZoom Defaults
Parameter
Setting
Zoom Vertical Position
Zoom Vertical Gain
Zoom Horizontal Position
Zoom Horizontal Gain
0
1X
Tracking Horizontal Position
1X
Press ZOOM ➞ Off (side) to return to normal oscilloscope (nonĆzoom)
operation.
See Acquisition, onpage 2Ć19.
For Further
Information
See Display Modes, onpage 3Ć26.
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Zoom
3Ć154
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Appendices
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Appendix A: Options and Accessories
This section describes the options, the standard accessories, and the opĆ
tional accessories that are available for the TDS 600A Digitizing OscilloĆ
scopes.
The following options are available:
Options
Options A1-A5: International Power Cords
Besides the standard North American, 110 V, 60 Hz power cord, Tektronix
ships any of five alternate power cordconfigurations with the oscilloscope
when ordered by the customer.
TableĂAĆ1:ăInternational Power Cords
Option
A1
Power Cord
Universal European Ċ 220 V, 50 Hz
UK Ċ 240 V, 50 Hz
A2
A3
Australian Ċ 240 V, 50 Hz
North American Ċ 240 V, 60 Hz
Switzerland Ċ 220 V, 50 Hz
A4
A5
Option 1K: K420 Scope Cart
With this option, Tektronix ships the K420 Scope Cart. The cart can help you
transport the oscilloscope aroundmany lab environments.
Service Assurance Options
The standard warranty appears following the title page in this manual. The
following options add to the services available with the standard warranty:
H
H
Option R2: When Option R2 is ordered, Tektronix provides two years of
postĆwarranty repair protection.
Option C5: When Option C5 is ordered, Tektronix provides five years of
calibration services.
H
Option M2: When Option M2 is ordered, Tektronix provides five years of
warranty/remedial service.
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Appendix A: Options and Accessories
Option 1F: File System (Standard on TDS 644A)
With this option, Tektronix ships thedigitizing oscilloscopewith a floppy disk
drive and a variety of features for managing the floppy disk. With the file
system you can save and recall setups, waveforms, and hardcopies on a
floppy disk.
Option 1R: Rackmounted Digitizing Oscilloscope
Tektronix ships the digitizing oscilloscope, when ordered with Option 1R,
configured for installation in a 19 inch wide instrument rack. Customers with
instruments not configured for rackmounting can order a rackmount kit
(016Ć1136Ć00 for field conversions).
Instructions for rackmounting thedigitizing oscilloscopeareshipped with the
Option 1R.
Option 13: RSĆ232/Centronics Hardcopy Interface
(Standard on TDS 644A)
With this option, Tektronix ships the oscilloscope equipped with a RSĆ232
and a Centronics interface that can be used to obtain hardcopies of the
oscilloscope screen.
Option 2D: Delete Two Probes (TDS 620A only)
With this option, Tektronix ships the instrument without the two probes
normally included as standard accessories.
Option 4D: Delete Four Probes (TDS 640A & 644A only)
With this option, Tektronix ships the instrument without the four probes
normally included as standard accessories.
Option 05: Video Trigger
With this option, Tektronix ships the instrument with tools for investigating
events that occur when a video signal generates a horizontal or vertical sync
pulse. It allows you to investigate a range of NTSC, PAL, SECAM, and
highĆdefinition TV signals.
Option 2F: Advanced DSP Math
(Standard on TDS 644A)
With this option, theoscilloscopecan computeand display threeadvanced
math waveforms: integral of a waveform, differential of a waveform, and an
FFT (Fast Fourier Transform) of a waveform.
AĆ2
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Appendix A: Options and Accessories
Option 23: Additional Probes Ċ (TDS 620A only)
With this option, Tektronix ships two additional probes identical to the two
standardĆaccessory P6205 probes normally shipped with the instrument.
This provides one probe for each frontĆpanel input.
Option 24: Add Four Passive Probes
With this option, Tektronix ships four passive 10X P6139A probes.
Option 95: Calibration Data Report
With this option, Tektronix ships a calibration data report with the
instrument.
Option 96: Calibration Certificate
With this option, Tektronix ships a Certificate of Calibration. This certificate
states the instrument meets or exceeds all warranted specifications and has
been calibrated using standards and instruments whose accuracies are
traceable to the National Institute of Standards and Technology, an accepted
value of a natural physical constant, or a ratioĆcalibration technique. The
calibration is in compliance with US MILĆSTDĆ45662A. This option includes a
test data report for the oscilloscope.
The following standard accessories are included with the digitizing oscilloĆ
scope:
Standard
Accessories
TableĂAĆ2:ăStandard Accessories
Accessory
Part Number
070Ć8715ĆXX
070Ć8709ĆXX
070Ć8711ĆXX
070Ć8717ĆXX
200Ć3696Ć00
161Ć0230Ć01
P6139A
User Manual
Programmer Manual
Reference
Performance Verification
Front Cover
U.S. Power Cord
Probes, TDS 640A, TDS 644A (quantity four),
10X Passive; 500 MHz
TDS 620A (quantity two), 10X Active;
750 MHz
P6205 (single unit)
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Appendix A: Options and Accessories
You can also order the following optional accessories:
Optional Accessories
TableĂAĆ3:ăOptional Accessories
Accessory
Part Number
070Ć8718ĆXX
HC100
Service Manual
Plotter (GPIB and Centronics Standard)
Oscilloscope Cart
K218
Rack Mount Kit (for field conversion)
Oscilloscope Camera
Oscilloscope Camera Adapter
SoftĆSided Carrying Case
Transit Case
016Ć1136Ć00
C9
016Ć1154Ć00
016Ć0909Ć01
016Ć1135Ć00
012Ć0991Ć01
012Ć0991Ć00
GPIB Cable (1 meter)
GPIB Cable (2 meter)
Accessory Probes
The following optional accessory probes are recommended for use with
your digitizing oscilloscope:
H
H
P6101A 1X, 15ĂMHz, Passive probe.
P6156 10X, 3.5 GHz, Passive, low capacitance, (low impedance Z )
probe.
O
H
H
H
P6205 10X, 750 MHz, Active probe
P6009 Passive, high voltage probe, 100X, 1500 VDC + Peak AC.
P6015A Passive high voltage probe, 1000X, 20 kVDC + Peak AC
(40 kV peak for less than 100 ms).
H
P6204 Active, high speed digital voltage probe. FET. DC to 1 GHz. DC
offset. 50 W input. Use with 1103 TekProbe Power Supply for offset
control.
H
H
H
H
P6563AS Passive, SMD probe, 20X, 500 MHz
P6046 Active, differential probe, 1X/10X, DC to 100 MHz, 50 W input.
A6501 Buffer Amplifier (active fixtured), 1 GHz, 1 MW, 10X.
P6501 Option 02: Microprobe with TekProbe power cable (active fixĆ
tured), 750 MHz, 1 MW, 10X.
H
AM 503S Ċ DC/AC Current probe system, AC/DC. Uses A6302 Current
Probe.
AĆ4
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Appendix A: Options and Accessories
H
AM 503S Option 03: DC/AC Current probe system, AC/DC. Uses A6303
Current Probe.
H
H
H
P6021 AC Current probe. 120 Hz to 60 MHz.
P6022 AC Current probe. 935 kHz to 120 MHz.
CTĆ1 Current probe Ċ designed for permanent or semi permanent
inĆcircuit installation. 25 kHz to 1 GHz, 50 W input.
H
H
H
H
H
H
H
CTĆ2 Current probe Ċ designed for permanent or semi permanent
inĆcircuit installation. 1.2 kHz to 200 MHz, 50 W input.
CTĆ4 Current Transformer Ċ for use with the AM 503S (A6302) and
P6021. Peak pulse 1 kA. 0.5 Hz to 20 MHz with AM 503S (A6302).
P6701A OptoĆElectronic Converter, 500 to 950 nm, DC to 850 MHz,
1 V/mW.
P6703A OptoĆElectronic Converter, 1100 to 1700 nm, DC to 1 GHz,
1 V/mW.
P6711 OptoĆElectronic Converter, 500 to 950 nm, DC to 250 MHz,
5 V/mW.
P6713 OptoĆElectronic Converter, 1100 to 1700 nm, DC to 300 MHz,
5 V/mW.
TVC 501 TimeĆtoĆvoltage converter. Time delay, pulse width and period
measurements.
Accessory Software
The following optional accessories are Tektronix software products recomĆ
mended for use with your digitizing oscilloscope:
TableĂAĆ4:ăAccessory Software
Software
Part Number
S45F030
EZĆTest Program Generator
Wavewriter: AWG and waveform creation
S3FT400
TekTMS: Test management system
LabWindows
S3FT001
S3FG910
Warranty Information
Check for the full warranty statements for this product, the probes, and the
products listed above on the first page after the title page of each product
manual.
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Appendix A: Options and Accessories
AĆ6
Appendices
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Appendix B: Algorithms
TDS 600A Digitizing Oscilloscopes can take 25 automatic measurements. By
knowinghow they make these calculations, you may better understand how
to use your TDS 600A and how to interpret your results.
TDS 600A Digitizing Oscilloscopes use a variety of variables in their calculaĆ
tions. These include:
Measurement
Variables
High, Low
High is the value used as the 100% level in measurements such as fall time
and rise time. For example, if you request the 10% to 90% rise time, then the
oscilloscope will calculate 10% and 90% as percentages with High repreĆ
senting100%.
Low is the value used as the 0% level in measurements such as fall time and
rise time.
The exact meaningof High and Low depends on which of two calculation
methods you choose from the HighĆLow Setup item of the Measure menu.
These are MinĆmax and Histogram.
MinĆMax Method Ċ defines the 0% and the 100% waveform levels as the
lowest amplitude (most negative) and the highest amplitude (most positive)
samples. The minĆmax method is useful for measuringfrequency, width, and
period for many types of signals. MinĆmax is sensitive to waveform ringing
and spikes, however, and does not always measure accurately rise time, fall
time, overshoot, and undershoot.
The minĆmax method calculates the High and Low values as follows:
High = Max
and
Low = Min
Histogram Method Ċ attempts to find the highest density of points above
and below the waveform midpoint. It attempts to ignore ringing and spikes
when determiningthe 0% and 100% levels. This method works well when
measuringsquare waves and pulse waveforms.
The oscilloscope calculates the histogramĆbased High and Low values as
follows:
1. It makes a histogram of the record with one bin for each digitizing level
(256 total).
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Appendix B: Algorithms
2. It splits the histogram into two sections at the halfway point between Min
and Max (also called Mid).
3. The level with the most points in the upper histogram is the High value,
and the level with the most points in the lower histogram is the Low
value. (Choose the levels where the histograms peakfor High and Low.)
If Mid gives the largest peakvalue within the upper or lower histogram,
then return the Mid value for both High and Low (this is probably a very
low amplitude waveform).
If more than one histogram level (bin) has the maximum value, choose
the bin farthest from Mid.
This algorithm does not workwell for twoĆlevel waveforms with greater than
about 100% overshoot.
HighRef, MidRef, LowRef, Mid2Ref
The user sets the various reference levels, through the Reference Level
selection of the Measure menu. They include:
HighRef Ċ the waveform high reference level. Used in fall time and rise
time calculations. Typically set to 90%. You can set it from 0% to 100% or to
a voltage level.
MidRef Ċ the waveform middle reference level. Typically set to 50%. You
can set it from 0% to 100% or to a voltage level.
LowRef Ċ the waveform low reference level. Used in fall and rise time
calculations. Typically set to 10%. You can set it from 0% to 100% or to a
voltage level.
Mid2Ref Ċ the middle reference level for a second waveform (or the seĆ
cond middle reference of the same waveform). Used in delay time calculaĆ
tions. Typically set to 50%. You can set it from 0% to 100% or to a voltage
level.
Other Variables
The oscilloscope also measures several values itself that it uses to help
calculate measurements.
RecordLength Ċ is the number of data points in the time base. You set it
with the Horizontal menu Record Length item.
Start Ċ is the location of the start of the measurement zone (XĆvalue). It is
0.0 samples unless you are making a gated measurement. When you use
gated measurements, it is the location of the left vertical cursor.
AĆ8
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Appendix B: Algorithms
End Ċ is the location of the end of the measurement zone (XĆvalue). It is
(RecordLength - 1.0) samples unless you are making a gated measurement.
When you use gated measurements, it is the location of the right vertical
cursor.
Hysteresis Ċ The hysteresis band is 10% of the waveform amplitude. It is
used in MCross1, MCross2, and MCross3 calculations.
For example, once a crossing has been measured in a negative direction,
the waveform data must fall below 10% of the amplitude from the MidRef
point before the measurement system is armed and ready for a positive
crossing. Similarly, after a positive MidRef crossing, waveform data must go
above 10% of the amplitude before a negative crossing can be measured.
Hysteresis is useful when you are measuring noisy signals, because it
allows the digitizing oscilloscope to ignore minor fluctuations in the signal.
MCross Calculations
MCross1, MCross2, and MCross3 Ċ refer to the first, second, and third
MidRef cross times, respectively. See Figure AĆ1.
The polarity of the crossings does not matter for these variables, but the
crossings alternate in polarity; that is, MCross1 could be a positive or negaĆ
tive crossing, but if MCross1 is a positive crossing, MCross2 will be a negative
crossing.
The oscilloscope calculates these values as follows:
1. Find the first MidRefCrossing in the waveform record or the gated region.
This is MCross1.
2. Continuing from MCross1, find the next MidRefCrossing in the waveform
record (or the gated region) of the opposite polarity of MCross1. This is
MCross2.
3. Continuing from MCross2, find the next MidRefCrossing in the waveform
record (or the gated region) of the same polarity as MCross1. This is
MCross3.
MCross1Polarity Ċ is the polarity of first crossing (no default). It can be
rising or falling.
StartCycle Ċ is the starting time for cycle measurements. It is a floatingĆ
point number with values between 0.0 and (RecordLength - 1.0), inclusive.
StartCycle = MCross1
EndCycle Ċ is the ending time for cycle measurements. It is a floatingĆ
point number with values between 0.0 and (RecordLength - 1.0), inclusive.
EndCycle = MCross3
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Appendix B: Algorithms
MCross1
(StartCycle)
MCross3
(EndCycle)
MCross2
MidRef + (Hysteresis x Amplitude)
MidRef
MidRef - (Hysteresis x Amplitude)
Figure AĆ1:ăMCross Calculations
Waveform[<0.0 ... RecordLength-1.0>] Ċ holds the acquired data.
TPOS Ċ is the location of the sample just before the trigger point (the time
reference zero sample). In other terms, it contains the domain reference
location. This location is where time = 0.
TSOFF Ċ is the offset between TPOS and the actual trigger point. In other
words, it is the trigger sample offset. Values range between 0.0 and 1.0
samples. This value is determined by the instrument when it receives a
trigger. The actual zero reference (trigger) location in the measurement
record is at (TPOS+TSOFF).
The automated measurements are defined and calculated as follows.
Measurement
Algorithms
Amplitude
Amplitude = High - Low
Area
The arithmetic area for one waveform. Remember that one waveform is not
necessarily equal to one cycle. For cyclical data you may prefer to use the
cycle area rather than the arithmetic area.
if Start = End then return the (interpolated) value at Start.
Otherwise,
End
ŕ
Area=
Waveform(t)dt
Start
AĆ10
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Appendix B: Algorithms
For details of the integration algorithm, see page AĆ17.
Cycle Area
Amplitude (voltage) measurement. The area over one waveform cycle. For
nonĆcyclical data, you might prefer to use the Area measurement.
If StartCycle = EndCycle then return the (interpolated) value at StartCycle.
EndCycle
ŕ
CycleMean=
Waveform(t)dt
StartCycle
For details of the integration algorithm, see page AĆ17.
Burst Width
Timing measurement. The duration of a burst.
1. Find MCross1 on the waveform. This is MCrossStart.
2. Find the last MCross (begin the search at EndCycle and search toward
StartCycle). This is MCrossStop. This could be a different value from
MCross1.
3. Compute BurstWidth = MCrossStop - MCrossStart
Cycle Mean
Amplitude (voltage) measurement. The mean over one waveform cycle. For
nonĆcyclical data, you might prefer to use the Mean measurement.
If StartCycle = EndCycle then return the (interpolated) value at StartCycle.
EndCycle
ŕ
Waveform(t)dt
StartCycle
CycleMean=
(EndCycle * StartCycle) SampleInterval
For details of the integration algorithm, see page AĆ17.
Cycle RMS
The true Root Mean Square voltage over one cycle.
If StartCycle = EndCycle then CycleRMS = Waveform[Start].
Otherwise,
EndCycle
(Waveform(t))2dt
ŕ
Ǹ
StartCycle
CycleRMS =
(EndCycle * StartCycle) SampleInterval
TDS 620A, 640A & 644A UserManual
AĆ11
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Appendix B: Algorithms
For details of the integration algorithm, see page AĆ17.
Delay
Timing measurement. The amount of time between the MidRef and Mid2Ref
crossings of two different traces, or two different places on the same trace.
Delay measurements are actually a group of measurements. To get a specifĆ
ic delay measurement, you must specify the target and reference crossing
polarities and the reference search direction.
Delay = the time from one MidRef crossing on the source waveform to
the Mid2Ref crossing on the second waveform.
Delay is not available in the Snapshot display.
Fall Time
Timing measurement. The time taken for the falling edge of a pulse to drop
from a HighRef value (default = 90%) to a LowRef value (default = 10%).
Figure AĆ2 shows a falling edge with the two crossings necessary to calcuĆ
late a Fall measurement.
1. Searching from Start to End, find the first sample in the measurement
zone greater than HighRef.
2. From this sample, continue the search to find the first (negative) crossĆ
ing of HighRef. The time of this crossing is THF. (Use linear interpolation
if necessary.)
3. From THF, continue the search, looking for a crossing of LowRef. UpĆ
date THF if subsequent HighRef crossings are found. When a LowRef
crossing is found, it becomes TLF. (Use linear interpolation if necesĆ
sary.)
4. FallTime = TLF - THF
AĆ12
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Appendix B: Algorithms
Fall Time
THF TLF
High
HighRef
LowRef
Low
Figure AĆ2:ăFall Time
Frequency
Timing measurement. The reciprocal of the period. Measured in Hertz (Hz)
where 1 Hz = 1 cycle per second.
If Period = 0 or is otherwise bad, return an error.
Frequency = 1/Period
High
100% (highest) voltage reference value. (See High, Low" earlier in this
section)
Using the minĆmax measurement technique:
High = Max
Low
0% (lowest) voltage reference value calculated. (See High, Low" earlier in
this section)
Using the minĆmax measurement technique:
Low = Min
TDS 620A, 640A & 644A User Manual
AĆ13
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Appendix B: Algorithms
Maximum
Amplitude (voltage) measurement. The maximum voltage. Typically the most
positive peak voltage.
Examine all Waveform[ ] samples from Start to End inclusive, and set
Max equal to the greatest magnitude Waveform[ ] value found.
Mean
The arithmetic mean for one waveform. Remember that one waveform is not
necessarily equal to one cycle. For cyclical data you may prefer to use the
cycle meanrather thanthe arithmetic mean.
If Start = End thenreturnthe (interpolated) value at Start.
Otherwise,
End
ŕ
Waveform(t)dt
Start
Mean=
(End * Start) SampleInterval
For details of the integration algorithm, see page AĆ17.
Minimum
Amplitude (voltage) measurement. The minimum amplitude. Typically the
most negative peak voltage.
Examine all Waveform[ ] samples from Start to End inclusive, and set Min
equal to the smallest magnitude Waveform[ ] value found.
Negative Duty Cycle
Timing measurement. The ratio of the negative pulse width to the signal
period expressed as a percentage.
NegativeWidth is defined in Negative Width, below.
If Period = 0 or undefined thenreturnanerror.
NegativeWidth
NegativeDutyCycle =
100%
Period
Negative Overshoot
Amplitude (voltage) measurement.
Low * Min
NegativeOvershoot =
100%
Amplitude
Note that this value should never be negative (unless High or Low are set
outĆofĆrange).
AĆ14
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Appendix B: Algorithms
Negative Width
Timingmeasurement. The distance (time) between MidRef (default = 50%)
amplitude points of a negative pulse.
If MCross1Polarity = `-'
then
NegativeWidth = (MCross2 - MCross1)
else
NegativeWidth = (MCross3 - MCross2)
Peak to Peak
Amplitude measurement. The absolute difference between the maximum
and minimum amplitude.
PeaktoPeak = Max - Min
Period
Timingmeasurement. Time taken for one complete signal cycle. The recipĆ
rocal of frequency. Measured in seconds.
Period = MCross3 - MCross1
Phase
Timingmeasurement. The amount of phase shift, expressed in degrees of
the target waveform cycle, between the MidRef crossings of two different
waveforms. Waveforms measured should be of the same frequency or one
waveform should be a harmonic of the other.
Phase is a dual waveform measurement; that is, it is measured from a target
waveform to a reference waveform. To get a specific phase measurement,
you must specify the target and reference sources.
Phase is determined in the followingmanner:
1. The first MidRefCrossing (MCross1Target) and third (MCross3) in the
source (target) waveform are found.
2. The period of the target waveform is calculated (see Period" above).
3. The first MidRefCrossing (MCross1Ref) in the reference waveform crossing
in the same direction (polarity) as that found MCross1Target for the target
waveform is found.
4. The phase is determined by the following:
MCross1Ref * MCross1Target
Phase =
360
Period
TDS 620A, 640A & 644A User Manual
AĆ15
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Appendix B: Algorithms
If the target waveform leads the reference waveform, phase is positive; if it
lags, negative.
Phaseis not availablein theSnapshot display.
Positive Duty Cycle
Timing measurement. Theratio of thepositivepulsewidth to thesignal
period, expressed as a percentage.
PositiveWidth is defined in Positive Width, following.
If Period = 0 or undefined then return an error.
PositiveWidth
PositiveDutyCycle =
100%
Period
Positive Overshoot
Amplitude (voltage) measurement.
Max * High
PositiveOvershoot =
100%
Amplitude
Note that this value should never be negative.
Positive Width
Timing measurement. The distance (time) between MidRef (default = 50%)
amplitudepoints of a positivepulse.
If MCross1Polarity = `+'
then
PositiveWidth = (MCross2 - MCross1)
else
PositiveWidth = (MCross3 - MCross2)
Rise Time
Timing measurement. Time taken for the leading edge of a pulse to rise from
a LowRef value(default = 10%) to a HighRef value(default = 90%).
FigureAĆ3 shows a rising edgewith thetwo crossings necessary to calcuĆ
late a Rise Time measurement.
1. Searching from Start to End, find thefirst samplein themeasurement
zoneless than LowRef.
2. From this sample, continuethesearch to find thefirst (positive) crossing
of LowRef. Thetimeof this crossing is thelow risetimeor
TLR. (Use
linear interpolation if necessary.)
AĆ16
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Appendix B: Algorithms
3. From TLR, continue the search, looking for a crossing of HighRef. UpĆ
date TLR if subsequent LowRef crossings are found. If a HighRef crossĆ
ing is found, it becomes the high rise time or THR. (Use linear
interpolation if necessary.)
4. RiseTime = THR - TLR
Rise Time
TLR THR
High
HighRef
LowRef
Low
Figure AĆ3:ăRise Time
RMS:
Amplitude (voltage) measurement. The true Root Mean Square voltage.
If Start = End then RMS = the (interpolated) value at Waveform[Start].
Otherwise,
End
Ă (Waveform(t))2dt
ŕ
Ǹ
Start
RMS =
(End * Start) SampleInterval
For details of the integration algorithm, see below.
Integration Algorithm
The integration algorithmused by the digitizing oscilloscope is as follows:
B
B
^
ŕ
is approximated by
ŕ
where:
W(t)dt
W(t)dt
A
A
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AĆ17
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Appendix B: Algorithms
W(t) is the sampled waveform
^
W(t)
is the continuous function obtained by linear interpolation of W(t)
A and B are numbers between 0.0 and RecordLength-1.0
If A and B are integers, then:
B
^
B*1 W(i) ) W(i ) 1)
ȍ
ŕ
W(t)dt + s
2
i+A
A
where s is the sample interval.
Similarly,
B
B
2
^
2
ǒ Ǔ
ŕ (
is approximated by
ŕ
where:
)
W(t) dt
W(t) dt
A
A
W(t) is the sampled waveform
^
W(t)
is the continuous function obtained by linear interpolation of W(t)
A and B are numbers between 0.0 and RecordLength-1.0
If A and B are integers, then:
B
2
2
B*1
2
(
)
(
)
^
W(i) ) W(i) W(i ) 1) ) W(i ) 1)
ǒ Ǔ
ȍ
ŕ
W(t) dt + s
3
i+A
A
where s is the sample interval.
Time measurements on envelope waveforms must be treated differently
from time measurements on other waveforms, because envelope waveforms
contain so many apparent crossings. Unless otherwise noted, envelope
waveforms use either the minima or the maxima (but not both), determined
in the following manner:
Measurements on
Envelope Waveforms
1. Step through the waveformfrom Start to End until the sample min and
max pair DO NOT straddle MidRef.
2. If the pair > MidRef, use the minima, else use maxima.
If all pairs straddle MidRef, use maxima. See Figure AĆ4.
The Burst Width measurement always uses both maxima and minima to
determine crossings.
AĆ18
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Appendix B: Algorithms
If some samples in the waveform are missing or offĆscale, the measurements
will linearly interpolate between known samples to make an appropriate"
guess as to the sample value. Missing samples at the ends of the measureĆ
ment record will be assumed to have the value of the nearest known samĆ
ple.
Missing or
OutĆofĆRange
Samples
When samples are out of range, the measurement will give a warning to that
effect (for example, CLIPPING") if the measurement could change by
extending the measurement range slightly. The algorithms assume the
samples recover from an overdrive condition instantaneously.
MidRef
Both min and max
samples are above
MidRef, so use
minima.
Both min and max
samples are below
MidRef, so use
maxima.
MidRef
Figure AĆ4:ăChoosing Minima or Maxima
to Use for Envelope Measurements
TDS 620A, 640A & 644A User Manual
AĆ19
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Appendix B: Algorithms
For example, if MidRef is set directly, then MidRef would not change even if
samples were out of range. However, if MidRef was chosen using the %
choice from the Set Levels in % Units selection of the Measure menu, then
MidRef could give a CLIPPING" warning.
NOTE
When measurements are displayed using Snapshot, out of range
warnings are NOT available. However, if you question the validity of
anymeasurement in the snapshot display, you can select and
displaythe measurement individuallyand then check for a warning
message.
AĆ20
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Appendix C: Packaging forShipment
If you ship the digitizing oscilloscope, pack it in the original shipping carton
and packing material. If the original packing material is not available, packĆ
age the instrument as follows:
1. Obtain a corrugated cardboard shipping carton with inside dimensions
at least 15Ăcm (6Ăin) taller, wider, and deeper than the digitizing oscilloĆ
scope. The shipping carton must be constructed of cardboard with
170 kg (375 pound) test strength.
2. If you are shipping the digitizing oscilloscope to a Tektronix field office
for repair, attach a tag to the digitizing oscilloscope showing the instruĆ
ment owner and address, the name of the person to contact about the
instrument, the instrument type, and the serialnumber.
3. Wrap the digitizing oscilloscope with polyethylene sheeting or equivalent
materialto protect the finish.
4. Cushion the digitizing oscilloscope in the shipping carton by tightly
packing dunnage or urethane foam on all sides between the carton and
the digitizing oscilloscope. Allow 7.5Ăcm (3Ăin) on all sides, top, and
bottom.
5. Sealthe shipping carton with shipping tape or an industrialstapel r.
NOTE
Do notship ht e digitizing oscilloscope with a disk inside the disk
drive (optional on TDS 620A & TDS 640A). When the disk is inside
the drive, the disk release button sticks out. This makes the button
more prone to damage than otherwise.
TDS 620A, 640A & 644A UserManual
AĆ21
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Appendix C: Packaging for Shipment
AĆ22
Appendices
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Appendix D: Factory
Initialization Settings
The factory initialization settings provide you a known state for the digitizing
oscilloscope.
Factory initialization sets values as shown in Table AĆ5.
Settings
TableĂAĆ5:ăFactory Initialization Defaults
Control
Changed by Factory Init to
Acquire mode
Sample
Acquire stop after
Acquire # of averages
Acquire # of envelopes
Channel selection
Cursor H Bar 1 position
RUN/STOP button only
16
10
Channel 1 on, all others off
10% of graticule height
(-3.2 divs from the center)
Cursor H Bar 2 position
90% of the graticule height
(+3.2 divs from the center)
Cursor VBar 1 position
Cursor VBar 2 position
Cursor amplitude units
Cursor mode
10% of the record length
90% of the record length
Base
Independent
Off
Cursor function
Cursor time units
Seconds
No change
DC
Date and time
Delayed edge trigger coupling
Delayed edge trigger level
Delayed edge trigger slope
Delayed edge trigger source
Delay trigger average #
0 V
Rising
Channel 1
16
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Appendix D: Factory Initialization Settings
TableĂAĆ5:ăFactory Initialization Defaults (Cont.)
Changed by Factory Init to
Control
Delay trigger envelope #
Delay time
10
16 ns
2
Delay events,
triggerable after main
Delayed, delay by ...
Delayed, time base mode
Display clock
Delay by Time
Delayed Runs After Main
No Change
Display color - collision contrast
(TDS 644A)
Off
Display color - map math colors
(TDS 644A)
Color `Math'
Color `Ref'
Normal
Display color - map reference colors
(TDS 644A)
Display color - palette
(TDS 644A)
Display color - palette colors
(TDS 644A)
The colors of each palette are reĆ
set to factory hue, saturation, and
lightness (HLS) values
Display color - persistence palette
(TDS 644A)
Temperature
Display format
YT
Display graticule type
Full
Display intensity - contrast
(TDS 620A & TDS 640A)
175%
Display intensity - text
TDS 620A & TDS 640A: 60%
TDS 644A: 100%
Display intensity - waveform
TDS 620A & TDS 640A: 80%
TDS 644A: 100%
Display intensity - overall
(TDS 620A & TDS 640A)
85%
Display interpolation filter
Display style
Sin(x)/x
Vectors
Short
Display trigger bar style
Display trigger T"
On
Display variable persistence
500 ms
AĆ24
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Appendix D: Factory Initialization Settings
TableĂAĆ5:ăFactory Initialization Defaults (Cont.)
Control
Changed by Factory Init to
Edge trigger coupling
Edge trigger level
Edge trigger slope
Edge trigger source
GPIB parameters
DC
0.0 V
Rising
Channel 1
No change
Hardcopy Format
Layout
Unchanged
Unchanged
Unchanged
Unchanged
Palette
Port
Horizontal - delay trigger position
Horizontal - delay time/division
Horizontal - fit to screen
50%
50 ms
Off
Horizontal - main trigger position
Horizontal - position
50%
50%
Horizontal - record length
Horizontal - main time/division
Horizontal - time base
500 points (10 divs)
500 ms
Main only
Limit template ±V Limit
±H Limit
40 mdiv
40 mdiv
Limit template destination
Limit template source
Limit test sources
Ref1
Ch1
Ch1 compared to Ref1; all others
compared to none.
Limit Testing
Off
Off
Limit Testing - hardcopy if condition
met
Limit Testing - ring bell if condition
met
Off
Logic pattern trigger Ch4 (Ax2) input
Logic state trigger Ch4 (Ax2) input
X (don't care)
Rising edge
Logic trigger input
(pattern and state)
Channel 1 = H (high),
Channels 2 & 3 (Ax1) = X (don't
care)
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AĆ25
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Appendix D: Factory Initialization Settings
TableĂAĆ5:ăFactory Initialization Defaults (Cont.)
Control
Changed by Factory Init to
Logic trigger pattern time qualification
Lower limit
5 ns
5 ns
Upper limit
Logic trigger threshold (all channels)
(pattern and state)
1.2 V
Logic trigger class
Pattern
AND
Logic trigger logic
(pattern and state)
Logic trigger triggers when ...
(pattern and state)
Goes TRUE
Main trigger holdoff
Main trigger mode
Main trigger type
0%
Auto
Edge
Math1 definition
Ch 1 + Ch 2
Math1 extended processing
Math2 definition
No extended processing
Ch 1 - Ch 2 (FFT of Ch 1 on
instruments with Option 2F AdĆ
vanced DSP Math)
Math2 extended processing
Math3 definition
No extended processing
Inv of Ch 1
Math3 extended processing
Measure Delay to
No extended processing
Channel 1 (Ch1)
Both rising and forward searching
Histogram
Measure Delay edges
Measure HighĆLow Setup
Measure High Ref
90% and 0 V (units)
10% and 0 V (units)
50% and 0 V (units)
50% and 0 V (units)
Positive
Measure Low Ref
Measure Mid Ref
Measure Mid2 Ref
Pulse glitch trigger polarity
Pulse runt high threshold
Pulse runt low threshold
Pulse runt trigger polarity
1.2 V
0.8 V
Positive
AĆ26
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Appendix D: Factory Initialization Settings
TableĂAĆ5:ăFactory Initialization Defaults (Cont.)
ControlChanged by Factory Init to
Pulse trigger class
Glitch
Pulse glitch filter state
Pulse glitch width
On (Accept glitch)
2.0 ns
Pulse trigger level
0.0 V
Pulse trigger source
Channel 1 (Ch1)
(Glitch, runt, andwidth)
Pulse width trigger when ...
Pulse width upper limit
Pulse width lower limit
Pulse width trigger polarity
Repetitive signal
Within limits
2.0 ns
2.0 ns
Positive
On
RSĆ232 parameters
No change
No change
No change
R/S button
Full
Savedsetups
Savedwaveforms
Stop after
Vertical bandwidth (all channels)
Vertical coupling (all channels)
DC
Vertical impedance (termination)
(all channels)
1 MW
Vertical offset (all channels)
Vertical position (all channels)
Vertical volts/division (all channels)
Zoom horizontal (all channels)
Zoom horizontal lock
0 V
0 divs.
100 mV/division
1.0X
All
Zoom horizontal position
(all channels)
50% = 0.5 (the middle of the
display)
Zoom state
Off
Zoom vertical (all channels)
Zoom vertical position (all channels)
1.0X
0 divisions
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AĆ27
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Appendix D: Factory Initialization Settings
AĆ28
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Glossary
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Glossary
AC coupling
A type of signal transmission that blocks the DC component of a
signal but uses the dynamic (AC) component. Useful for observing
an AC signal that is normally riding on a DC signal.
Accuracy
The closeness of the indicated value to the true value.
Acquisition
The process of sampling signals from input channels, digitizing the
samples into data points, and assembling the data points into a
waveform record. The waveform record is stored inmemory. The
trigger marks time zero inthat process.
Acquisition interval
The time durationof the waveform record divided by the record
length. The digitizing oscilloscope displays one data point for every
acquisitioninterval.
Active cursor
The cursor that moves whenyou turnthe general purpose knob. It is
represented in the display by a solid line. The @ readout on the
display shows the absolute value of the active cursor.
Aliasing
A false representation of a signal due to insufficient sampling of high
frequencies or fast transitions. A condition that occurs when a
digitizing oscilloscope digitizes at an effective sampling rate that is
too slow to reproduce the input signal. The waveform displayed on
the oscilloscope may have a lower frequency than the actual input
signal.
Amplitude
The High waveform value less the Low waveform value.
AND
A logic (Boolean) function in which the output is true when and only
whenall the inputs are true. Onthe digitizing oscilloscope, that is a
trigger logic pattern and state function.
Area
Measurement of the waveform area taken over the entire waveform
or the gated region. Expressed in voltĆseconds. Area above ground
is positive; area below ground is negative.
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Glossary
Attenuation
The degree the amplitude of a signal is reduced when it passes
through an attenuating device such as a probe or attenuator. That is,
the ratio of the input measure to the output measure. For example, a
10X probe will attenuate, or reduce, the input voltage of a signal by
a factor of 10.
Automatic trigger mode
A trigger modethat causes theoscilloscopeto automatically acquire
if triggerable events are not detected within a specified time period.
Autoset
A function of theoscilloscopethat automatically produces a stable
waveform of usable size. Autoset sets up frontĆpanel controls based
on the characteristics of the active waveform. A successful autoset
will set the volts/div, time/div, and trigger level to produce a coherent
and stablewaveform display.
Average acquisition mode
In this modetheoscilloscopeacquires and displays a waveform that
is the averaged result of several acquisitions. Averaging reduces the
apparent noise. The oscilloscope acquires data as in the sample
mode and then averages it according to a specified number of
averages.
Bandwidth
Thehighest frequency signal theoscilloscopecan acquirewith no
morethan 3 dB (× .707) attenuation of the original (reference) signal.
Burst width
A timing measurement of the duration of a burst.
Channel
Onetypeof input used for signal acquisition. TheTDS 644A &
TDS 640A havefour channels; theTDS 620A has two.
Channel Reference Indicator
Theindicator on theleft sideof thedisplay that points to theposition
around which the waveform contracts or expands when vertical
scale is changed. This position is ground when offset is set to 0ĂV;
otherwise, it is ground plus offset.
Coupling
Theassociation of two or morecircuits or systems in such a way
that power or information can be transferred from one to the other.
You can coupletheinput signal to thetrigger and vertical systems
several different ways.
Cursors
Paired markers that you can use to make measurements between
two waveform locations. Theoscilloscopedisplays thevalues (exĆ
pressed in volts or time) of the position of the active cursor and the
distance between the two cursors.
GlossaryĆ2
Glossary
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Glossary
Cycle area
A measurement of waveform area taken over one cycle. Expressed
in voltĆseconds. Area above ground is positive; area below ground is
negative.
Cycle mean
An amplitude (voltage) measurement of the arithmetic mean over
one cycle.
Cycle RMS
The true Root Mean Square voltage over one cycle.
DC coupling
A mode that passes both AC and DC signal components to the
circuit. Available for both the trigger system and the vertical system.
Delay measurement
A measurement of the time between the middle reference crossings
of two different waveforms.
Delay time
The time between the trigger event and the acquisition of data.
Digitizing
The process of converting a continuous analog signal such as a
waveform to a set of discrete numbers representing the amplitude of
the signal at specific points in time. Digitizing is composed of two
steps: sampling and quantizing.
Display system
The part of the oscilloscope that shows waveforms, measurements,
menu items, status, and other parameters.
Edge Trigger
Triggering occurs when the oscilloscope detects the source passing
through a specified voltage level in a specified direction (the trigger
slope).
Envelope acquisition mode
A mode in which the oscilloscope acquires and displays a waveform
that shows the variation extremes of several acquisitions.
Fall time
A measurement of the time it takes for trailing edge of a pulse to fall
from a HighRef value (typically 90%) to a LowRef value (typically
10%) of its amplitude.
Frequency
A timing measurement that is the reciprocal of the period. Measured
in Hertz (Hz) where 1 Hz = 1 cycle per second.
Gated Measurements
A feature that lets you limit automated measurements to a specified
portion of the waveform. You define the area of interest using the
vertical cursors.
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Glossary
General purpose knob
The large frontĆpanel knob with an indentation. You can use it to
change the value of the assigned parameter.
Glitch positive trigger
Triggering occurs if the oscilloscope detects positive spike widths
less than the specified glitch time.
Glitch negative trigger
Triggering occurs if the oscilloscope detects negative spike widths
less than the specified glitch time.
Glitch either trigger
Triggering occurs if the oscilloscope detects either positive or negaĆ
tive spike widths less than the specified glitch time.
GPIB (General Purpose Interface Bus)
An interconnection bus and protocol that allows you to connect
multiple instruments in a network under the control of a controller.
Also known as IEEE 488 bus. It transfers data with eight parallel
data lines, five control lines, and three handshake lines.
Graticule
A grid on the display screen that creates the horizontal and vertical
axes. You can use it to visually measure waveform parameters.
Ground (GND) coupling
Coupling option that disconnects the input signal fromthe vertical
system.
Hardcopy
An electronic copy of the display in a format useable by a printer or
plotter.
High
The value used as 100% in automated measurements (whenever
high ref, mid ref, and low ref values are needed as in fall time and
rise time measurements). May be calculated using either the min/
max or the histogram method. With the min/max method (most
useful for general waveforms), it is the maximum value found. With
the histogram method (most useful for pulses), it refers to the most
common value found above the mid point. See Appendix B: AlgoĆ
rithms for details.
Holdoff, trigger
A specified amount of time after a trigger signal that elapses before
the trigger circuit will accept another trigger signal. Trigger holdoff
helps ensure a stable display.
Horizontal bar cursors
The two horizontal bars that you position to measure the voltage
parameters of a waveform. The oscilloscope displays the value of
the active (moveable) cursor with respect to ground and the voltage
value between the bars.
GlossaryĆ4
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Interpolation
The way the digitizing oscilloscope calculates values for record
points when the oscilloscope cannot acquire all the points for a
complete record with a single trigger event. That condition occurs
when the oscilloscope is limited to real time samplingand the time
base is set to a value that exceeds the effective sample rate of the
oscilloscope. The digitizing oscilloscope has two interpolation opĆ
tions: linear or sin(x)/x interpolation.
Linear interpolation calculates record points in a straightĆline fit
between the actual values acquired. Sin(x)/x computes record
points in a curve fit between the actual values acquired. It assumes
all the interpolated points fall in their appropriate point in time on
that curve.
Intensity
Display brightness.
Knob
A rotary control.
Logic state trigger
The oscilloscope checks for defined combinatorial logic conditions
on channels 1, 2, and 3 on a transition of channel 4 that meets the
set slope and threshold conditions. If the conditions of channels 1,
2, and 3 are met then the oscilloscope triggers.
Logic pattern trigger
The oscilloscope triggers depending on the combinatorial logic
condition of channels 1, 2, 3, and 4. Allowable conditions are AND,
OR, NAND, and NOR.
Low
The value used as 0% in automated measurements (whenever high
ref, mid ref, and low ref values are needed as in fall time and rise
time measurements). May be calculated usingeither the min/max or
the histogram method. With the min/max method (most useful for
general waveforms), it is the minimum value found. With the histoĆ
gram method (most useful for pulses), it refers to the most common
value found below the mid point. See Appendix B: Algorithms for
details.
Main menu
A group of related controls for a major oscilloscope function that the
oscilloscope displays across the bottom of the screen.
Main menu buttons
Bezel buttons under the main menu display. They allow you to select
items in the main menu.
Maximum
Amplitude (voltage) measurement of the maximum amplitude.
Typically the most positive peak voltage.
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Mean
Amplitude (voltage) measurement of the arithmetic mean over the
entire waveform.
Minimum
Amplitude (voltage) measurement of the minimum amplitude. TypiĆ
cally the most negative peak voltage.
NAND
A logic (Boolean) function in which the output of the AND function is
complemented (true becomes false, and false becomes true). On
the digitizing oscilloscope, that is a trigger logic pattern and state
function.
Negative duty cycle
A timing measurement representing the ratio of the negative pulse
width to the signal period, expressed as a percentage.
Negative overshoot measurement
Amplitude (voltage) measurement.
Low * Min
NegativeOvershoot +
100%
Amplitude
Negative width
A timing measurement of the distance (time) between two amplitude
points Ċ fallingĆedge MidRef (default 50%) and risingĆedge MidRef
(default 50%) Ċ on a negative pulse.
Normal trigger mode
A mode on which the oscilloscope does not acquire a waveform
record unless a valid trigger event occurs. It waits for a valid trigger
event before acquiring waveform data.
NOR
A logic (Boolean) function in which the output of the OR function is
complemented (true becomes false, and false becomes true). On
the digitizing oscilloscope, that is a trigger logic pattern and state
function.
OR
A logic (Boolean) function in which the output is true if any of the
inputs are true. Otherwise the output is false. On the digitizing
oscilloscope, that is a trigger logic pattern and state function.
Oscilloscope
An instrument for making a graph of two factors. These are typically
voltage versus time.
PeakĆtoĆPeak
Amplitude (voltage) measurement of the absolute difference beĆ
tween the maximum and minimum amplitude.
Period
A timing measurement of the time covered by one complete signal
cycle. It is the reciprocal of frequency and is measured in seconds.
GlossaryĆ6
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Phase
A timing measurement between two waveforms of the amount one
leads or lags the other in time. Phase is expressed in degrees,
where 360° comprise one complete cycle of one of the waveforms.
Waveforms measured should be of the same frequency or one
waveform should be a harmonic of the other.
Pixel
A visible point on the display. The oscilloscope display is 640 pixels
wide by 480 pixels high.
PopĆup Menu
A subĆmenu of a main menu. PopĆup menus temporarily occupy
part of the waveform display area and are used to present additional
choices associated with the main menu selection. You can cycle
through the options in a popĆup menu by repeatedly pressing the
main menu button underneath the popĆup.
Positive duty cycle
A timing measurement of the ratio of the positive pulse width to the
signal period, expressed as a percentage.
Positive overshoot
Amplitude (voltage) measurement.
Max * High
PositiveOvershoot +
100%
Amplitude
Positive width
A timing measurement of the distance (time) between two amplitude
points Ċ risingĆedge MidRef (default 50%) and fallingĆedge MidRef
(default 50%) Ċ on a positive pulse.
Posttrigger
The specified portion of the waveform record that contains data
acquired after the trigger event.
Pretrigger
The specified portion of the waveform record that contains data
acquired before the trigger event.
Probe
An oscilloscope input device.
Quantizing
The process of converting an analog input that has been sampled,
such as a voltage, to a digital value.
Probe compensation
Adjustment that improves lowĆfrequency response of a probe.
Pulse trigger
A trigger mode in which triggering occurs if the oscilloscope finds a
pulse, of the specified polarity, with a width between, or optionally
outside, the userĆspecified lower and upper time limits.
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GlossaryĆ7
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RealĆtime sampling
A sampling mode where the digitizing oscilloscope samples fast
enough to completely fill a waveform record from a single trigger
event. Use realĆtime sampling to capture singleĆshot or transient
events. (All TDS 600A series oscilloscopes use real time sampling at
all acquisition rates.)
Record length
The specified number of samples in a waveform.
Reference memory
Memory in a oscilloscope used to store waveforms or settings. You
can use that waveform data later for processing. The digitizing
oscilloscope saves the data even when the oscilloscope is turned off
or unplugged.
Rise time
The time it takes for a leading edge of a pulse to rise from a LowRef
value (typically 10%) to a HighRef value (typically 90%) of its ampliĆ
tude.
RMS
Amplitude (voltage) measurement of the true Root Mean Square
voltage.
Runt trigger
A mode in which the oscilloscope triggers on a runt. A runt is a
pulse that crosses one threshold but fails to cross a second threshĆ
old before recrossing the first. The crossings detected can be posiĆ
tive, negative, or either.
Sample acquisition mode
The oscilloscope creates a record point by saving the first sample
during each acquisition interval. That is the default mode of the
acquisition.
Sample interval
The time intervalbetween successive sampel s in a time base. For
realĆtime digitizers, the sample interval is the reciprocal of the samĆ
ple rate. For equivalentĆtime digitizers, the time interval between
successive samples represents equivalent time, not real time.
Sampling
The process of capturing an analog input, such as a voltage, at a
discrete point in time and holding it constant so that it can be quanĆ
tized. Two generalmethods of sampilng are: realĆtime sampling and
equivalentĆtime sampling.
Select button
A button that changes which of the two cursors is active.
Selected waveform
The waveform on which all measurements are performed, and which
is affected by vertical position and scale adjustments. The light over
one of the channel selector buttons indicates the current selected
waveform.
GlossaryĆ8
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Side menu
Menuthat appears to the right of the display. These selections
expand on main menuselections.
Side menu buttons
Bezel buttons to the right of the side menu display. They allow you
to select items in the side menu.
Slope
The direction at a point on a waveform. Youcan calculate the direcĆ
tion by computing the sign of the ratio of change in the vertical
quantity (Y) to the change in the horizontal quantity. The two values
are rising and falling.
Tek Secure
This feature erases all waveform and setup memory locations (setup
memories are replaced with the factory setup). Then it checks each
location to verify erasure. This feature finds use where this digitizing
oscilloscope is used to gather security sensitive data, such as is
done for research or development projects.
Time base
The set of parameters that let youdefine the time and horizontal axis
attributes of a waveform record. The time base determines when
and how long to acquire record points.
Trigger
An event that marks time zero in the waveform record. It results in
acquisition and display of the waveform.
Trigger level
The vertical level the trigger signal must cross to generate a trigger
(on edge trigger mode).
Vertical bar cursors
The two vertical bars youposition to measure the time parameter of
a waveform record. The oscilloscope displays the value of the active
(moveable) cursor with respect to the trigger and the time value
between the bars.
Waveform
The shape or form (visible representation) of a signal.
Waveform interval
The time interval between record points as displayed.
XY format
A display format that compares the voltage level of two waveform
records point by point. It is useful for studying phase relationships
between two waveforms.
YT format
The conventional oscilloscope display format. It shows the voltage of
a waveform record (on the vertical axis) as it varies over time (on the
horizontal axis).
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GlossaryĆ10
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Index
Stop After Limit Test Condition
Met, 3Ć73
Template Source, 3Ć70
AUTOSET button, 1Ć12, 3Ć8, 3Ć128
AUX TRIGGER INPUT, BNC, 2Ć5
Auxiliary trigger, 2Ć14
Numbers
V Limit, 3Ć71
1/seconds (Hz), Cursor menu, 3Ć19
100 MHz, Vertical menu, 3Ć138
20 MHz, Vertical menu, 3Ć138
Average acquisition mode, 3Ć5, GlosĆ
saryĆ2
ACQUIRE MENU button, 3Ć5, 3Ć70
Acquisition, 2Ć19ć2Ć21, 3Ć8, GlossaryĆ1
Average mode, Acquire menu, 3Ć71
Average, Acquire menu, 3Ć5
Average, More menu, 3Ć149
Interval, GlossaryĆ1
Modes
Average, 3Ć5
Envelope, 3Ć4
Sample, 3Ć3
A
Readout, 3Ć5
AC coupling, 2Ć16ć2Ć17, GlossaryĆ1
AC line voltage, trigger input, 2Ć14
AC, Main Trigger menu, 3Ć33
Active cursor, GlossaryĆ1
B
Active voltage probes, 3Ć104ć3Ć105
active, Saved waveform status, 3Ć123
Algorithms, AĆ7ćAĆ20
Bandwidth, 1Ć1, 2Ć21, GlossaryĆ2
Bandwidth, Vertical menu, 3Ć138
Base, Cursor menu, 3Ć19
Accept Glitch, Main Trigger menu,
3Ć112
Aliasing, 2Ć24, 3Ć46, GlossaryĆ1
Amplitude, 3Ć83, GlossaryĆ1
Amplitude Units, Cursor menu, 3Ć19
AND, GlossaryĆ1
Accessories, AĆ1ćAĆ6
Optional, AĆ4
Baud Rate, Utility menu, 3Ć58
BlackmanĆHarris window, 3Ć39
BMP, 3Ć57
Probes, AĆ4ćAĆ6
Software, AĆ5ćAĆ6
Standard, AĆ3, AĆ5
AND, Main Trigger menu, 3Ć79, 3Ć82
Accuracy, GlossaryĆ1
BMP Color, Hardcopy menu, 3Ć59
BMP Mono, Hardcopy menu, 3Ć59
Applications
Acquire menu, 3Ć5, 3Ć70
Average, 3Ć5
derivative math waveforms, 3Ć139
FFT math waveforms, 3Ć36
integral math waveforms, 3Ć143
BNC
Average mode, 3Ć71
AUX TRIGGER INPUT, 2Ć5
DELAYED TRIGGER OUTPUT, 2Ć5
MAIN TRIGGER OUTPUT, 2Ć5
SIGNAL OUTPUT, 2Ć5
Compare Ch1 to, 3Ć72
Compare Ch2 to, 3Ć72
Compare Ch3 to, 3Ć72
Compare Ch4 to, 3Ć72
Compare Math1 to, 3Ć72
Compare Math2 to, 3Ć72
Compare Math3 to, 3Ć72
Create Limit Test Template, 3Ć70
Envelope, 3Ć5
H Limit, 3Ć71
Hardcopy if Condition Met, 3Ć73
Limit Test, 3Ć73
Limit Test Condition Met, 3Ć73
Limit Test Setup, 3Ć72, 3Ć73
Limit Test Sources, 3Ć72
Mode, 3Ć5
OK Store Template, 3Ć71
Ring Bell if Condition Met, 3Ć73
RUN/STOP, 3Ć6
Area, 3Ć83, GlossaryĆ1
Attenuation, GlossaryĆ2
Auto, Main Trigger menu, 3Ć35, 3Ć79,
3Ć111
Bold, Color menu, 3Ć11
Burst width, 3Ć83
Automated Measurements, Snapshot
Button
of, 1Ć22
ACQUIRE MENU, 3Ć5, 3Ć70
AUTOSET, 1Ć12, 2Ć24, 3Ć8, 3Ć128
CLEAR MENU, 1Ć10, 1Ć19, 1Ć20,
Automated measurements, 1Ć18, 2Ć26,
3Ć83
of derivative math waveforms,
3Ć140
(procedure), 3Ć140
of FFT math waveforms, 3Ć41
2Ć3, 2Ć8, 3Ć92
CURSOR, 2Ć27, 3Ć17
DELAYED TRIG, 2Ć18, 3Ć23
DISPLAY, 3Ć10, 3Ć26
FORCE TRIG, 3Ć133
HARDCOPY, 3Ć53, 3Ć59, 3Ć118
HELP, 3Ć65
HORIZONTAL MENU, 2Ć18, 3Ć21
MEASURE, 3Ć86
MORE, 3Ć124, 3Ć126, 3Ć148
ON/STBY, 1Ć5, 2Ć3
of integral math waveforms, 3Ć146
Automatic trigger mode, 2Ć15, GlossaĆ
ryĆ2
Autosave, Save/Recall Waveform
menu, 3Ć125
Sample, 3Ć5
Single Acquisition Sequence, 3Ć7
Stop After, 3Ć6, 3Ć73
Autoset, 1Ć11, 2Ć25, 3Ć8ć3Ć9, GlossaĆ
ryĆ2
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Index
Save/Recall SETUP, 1Ć8, 3Ć53,
3Ć120
Channelreference indicator, GlossaĆ
ryĆ2
Compare Ch3 to, Acquire menu, 3Ć72
Compare Ch4 to, Acquire menu, 3Ć72
Save/Recall WAVEFORM, 3Ć53,
3Ć123
Circuit loading, GlossaryĆ2
Compare Math1 to, Acquire menu,
3Ć72
Class, Main Trigger menu, 3Ć77,
SELECT, 2Ć27, 3Ć18, GlossaryĆ8
SET LEVEL TO 50%, 3Ć133
SINGLE TRIG, 3Ć7, 3Ć133
STATUS, 3Ć130
TOGGLE, 3Ć18
TRIGGER MENU, 3Ć32, 3Ć77,
3Ć111, 3Ć113
Compare Math2 to, Acquire menu,
3Ć72
CLEAR MENU button, 1Ć10, 1Ć19,
1Ć20, 2Ć3, 2Ć8, 3Ć92
Compare Math3 to, Acquire menu,
3Ć72
Clear Spool, Hardcopy menu, 3Ć60
Clipping
Compensation, 3Ć100
3Ć111, 3Ć113, 3Ć135
derivative math waveforms, 3Ć141
FFT math waveforms, 3Ć44
how to avoid, 3Ć44, 3Ć141, 3Ć146
integralmath waveforms, 3Ć146
UTILITY, 3Ć58, 3Ć118
Configure, Utility menu, 3Ć58, 3Ć118
VERTICAL MENU, 1Ć15
WAVEFORM OFF, 1Ć17, 3Ć30, 3Ć127
ZOOM, 2Ć25, 3Ć151
Confirm Delete, File Utilities menu,
3Ć56
Connector
Collision Contrast, Color menu, 3Ć14
Buttons
AUX TRIGGER INPUT, 2Ć5
Centronics, 2Ć5
DELAYED TRIGGER OUTPUT, 2Ć5
GPIB, 2Ć5, 3Ć117
MAIN TRIGGER OUTPUT, 2Ć5
Power, 2Ć5
RSĆ232, 2Ć5
CH1, CH2 ..., 3Ć126
Channelseel ction, 1Ć14, 3Ć126
Main menu, 2Ć3
Color, 3Ć10ć3Ć14
Color Matches Contents, Color
menu, 3Ć13
Side menu, 2Ć3
Color menu, 3Ć10
Bold, 3Ć11
Change Colors, 3Ć11
Collision Contrast, 3Ć14
Color, 3Ć12, 3Ć13
Color Matches Contents, 3Ć13
Hardcopy, 3Ć11
Hue, 3Ć12
Lightness, 3Ć12
Map Math, 3Ć12
Map Reference, 3Ć13
Math, 3Ć12
Monochrome, 3Ć11
Normal, 3Ć11
Options, 3Ć14
Palette, 3Ć11
Persistence Palette, 3Ć11
Ref, 3Ć13
SIGNAL OUTPUT, 2Ć5
VGA, 2Ć5
C
Contrast, Display menu, 3Ć27
Conventions, ii
Cables, 3Ć117, 3Ć118
Cal Probe, Verticalmenu, 3Ć94
Calibration Certificate, AĆ3
Calibration Data Report, AĆ3
Cart, Oscilloscope, AĆ1
Copy, File Utilities menu, 3Ć55
Coupling, 1Ć15
AC, 2Ć16
DC, 2Ć16
Ground, GlossaryĆ4
Input Signal, 2Ć21
Trigger, 2Ć16
CAUTION
statement in manuals, xi
statement on equipment, xi
Coupling, Delayed Trigger menu,
3Ć24
Centronics, 2Ć5
Port, 3Ć59
Coupling, Main Trigger menu, 3Ć33
Reset All Mappings To Factory,
3Ć14
CH1, CH2 ... buttons, 3Ć126
Coupling, Verticalmenu, 3Ć137
Reset All Palettes To Factory, 3Ć14
Reset Current Palette To Factory,
3Ć14
Ch1, Ch2 ..., Delayed Trigger menu,
3Ć24
Create Directory, File Utilities menu,
3Ć55
Ch1, Ch2 ..., Main Trigger menu,
3Ć32, 3Ć78, 3Ć79, 3Ć81, 3Ć111,
3Ć113
Reset to Factory Color, 3Ć12
Restore Colors, 3Ć14
Saturation, 3Ć12
Spectral, 3Ć11
Temperature, 3Ć11
View Palette, 3Ć11
Create Limit Test Template, Acquire
menu, 3Ć70
Create Measrmnt, Measure Delay
Change Colors, Color menu, 3Ć11
menu, 3Ć92
Change Math waveform definition,
Cross Hair, Display menu, 3Ć29
More menu, 3Ć149
Current probes, 3Ć105
Channel, 3Ć126ć3Ć127, GlossaryĆ2
Readout, 2Ć6, 3Ć126
Color, Color menu, 3Ć12, 3Ć13
Cursor
Color, Display menu, 3Ć10
Horizontalbar, 2Ć27, 3Ć15
Measurements, 2Ć27
Reference Indicator, 2Ć6
Selection buttons, 1Ć14, 3Ć126
Trigger input, 2Ć13ć2Ć18
Compare Ch1 to, Acquire menu, 3Ć72
Compare Ch2 to, Acquire menu, 3Ć72
Channelreadout, 2Ć6
IndexĆ2
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Mode, 2Ć27ć2Ć28
Independent, 2Ć27ć2Ć28
Tracking, 2Ć28
Paired, 2Ć27, 3Ć15
Vertical bar, 2Ć27, 3Ć15
Delay by Events, Delayed Trigger
Differentiation
menu, 3Ć23
of a derivative, 3Ć139
waveform, 3Ć139
Delay by Time, Delayed Trigger
menu, 3Ć23
Digitizing, GlossaryĆ3
Digitizing rate, 1Ć1
Delay by, Delayed Trigger menu, 3Ć23
Delay measurement, 3Ć90, GlossaryĆ3
Delay time, GlossaryĆ3
CURSOR button, 3Ć17
Disk drive, 3Ć53ć3Ć56
Cursor menu, 3Ć17, 3Ć40, 3Ć144
1/seconds (Hz), 3Ć19
Amplitude Units, 3Ć19
Base, 3Ć19
Display, 2Ć6, 3Ć8
Options, 3Ć26ć3Ć31
Record View, 3Ć134
System, GlossaryĆ3
Delay To, Measure Delay menu, 3Ć90
Delayed Only, Horizontal menu, 3Ć21
Delayed Runs After Main, 2Ć18
Function, 3Ć17, 3Ć18
H Bars, 3Ć17, 3Ć18
Independent, 3Ć18
IRE (NTSC), 3Ć19
seconds, 3Ć19
Time Units, 3Ć19
Tracking, 3Ć18
Video Line Number, 3Ć19
Display `T' @ Trigger Point, Display
Delayed Runs After Main, Horizontal
menu, 3Ć28
menu, 3Ć21, 3Ć68
DISPLAY button, 3Ć10, 3Ć10, 3Ć26
Delayed Scale, Horizontal menu, 3Ć68
DELAYED TRIG button, 2Ć18, 3Ć23
Delayed trigger, 2Ć18, 3Ć20ć3Ć25
Display menu, 3Ć10, 3Ć26
Color, 3Ć10
Contrast, 3Ć27
Cross Hair, 3Ć29
Display, 3Ć26
Display `T' @ Trigger Point, 3Ć28
Dots, 3Ć27
Dots style, 3Ć72
Filter, 3Ć29
Format, 3Ć30
Frame, 3Ć29
Full, 3Ć29
Graticule, 3Ć29
Grid, 3Ć29
Infinite Persistence, 3Ć27
Intensified Samples, 3Ć27
Intensity, 3Ć27
Linear interpolation, 3Ć29
NTSC, 3Ć29
Cursor readout
Delayed Trigger menu, 3Ć23ć3Ć25
Ch1, Ch2 ..., 3Ć24
Coupling, 3Ć24
HĆBars, 3Ć40, 3Ć141, 3Ć145
Paired, 3Ć141
Paired cursors, 3Ć41, 3Ć145
VĆBars, 3Ć40, 3Ć141, 3Ć145
Delay by, 3Ć23
Delay by Events, 3Ć23
Delay by Time, 3Ć23
Falling edge, 3Ć24
Level, 3Ć24
Rising edge, 3Ć24
Set to 50%, 3Ć25
Set to ECL, 3Ć24
Set to TTL, 3Ć24
Slope, 3Ć24
Cursor Readouts, 3Ć16
Cursor Speed, 3Ć19
Cursors, 2Ć27, 3Ć15ć3Ć19, GlossaryĆ2
with derivative waveforms, 3Ć141
with FFT waveforms, 3Ć40
with integral waveforms, 3Ć144
Cyclearea, 3Ć83, GlossaryĆ3
Cyclemean, 3Ć83, GlossaryĆ3
CycleRMS, 3Ć83, GlossaryĆ3
Source, 3Ć24
DELAYED TRIGGER OUTPUT, BNC,
2Ć5
Overall, 3Ć27
PAL, 3Ć29
Readout, 3Ć28
Delayed Triggerable, 2Ć18
Delayed Triggerable, Horizontal
Settings, 3Ć10, 3Ć26
Sin(x)/x interpolation, 3Ć29
Style, 3Ć26
Text/Grat, 3Ć27
Trigger Bar, 3Ć28
Variable Persistence, 3Ć27
Vectors, 3Ć27
Waveform, 3Ć27
XY, 3Ć30
YT, 3Ć30
menu, 3Ć23, 3Ć68
D
Delete Refs, Save/Recall Waveform
menu, 3Ć124
DANGER, statement on equipment, xi
Delete, File Utilities menu, 3Ć54
Date/Time
Derivative math waveform, 3Ć139
applications, 3Ć139
On hardcopies, 3Ć60
To set, 3Ć60
derivation of, 3Ć139
procedure for displaying, 3Ć139
procedure for measuring, 3Ć140,
3Ć141
DC coupling, 2Ć16, GlossaryĆ3
DC offset, 3Ć44
Display, Display menu, 3Ć26
Display, Status menu, 3Ć130
Dots, 3Ć27
for DC correction of FFTs, 3Ć44
with math waveforms, 3Ć44, 3Ć146
record length of, 3Ć139
Deskjet, 3Ć57
DC, Main Trigger menu, 3Ć33
Deskjet, Hardcopy menu, 3Ć59
Differential active probes, 3Ć104
Define Inputs, Main Trigger menu,
Dots style, Display menu, 3Ć72
3Ć79, 3Ć81
Define Logic, Main Trigger menu,
3Ć79, 3Ć82
TDS 620A, 640A & 644A User Manual
IndexĆ3
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Index
Dots, Display menu, 3Ć27
Fast Fourier Transforms (FFTs), apĆ
Format, Display menu, 3Ć30
Format, File Utilities menu, 3Ć56
Format, Hardcopy menu, 3Ć59
Frame, Display menu, 3Ć29
Frequency, 1Ć19, 3Ć84, GlossaryĆ3
Front Cover removal, 1Ć5
Front panel, 2Ć4
plications, 3Ć36
DPU411-II, Hardcopy menu, 3Ć59
DPU412, Hardcopy menu, 3Ć59
Dual Wfm Math, More menu, 3Ć149
FastFrame interactions, 3Ć17
FFT frequency domain record, 3Ć42
defined, 3Ć42ć3Ć52
Duty cycle, 1Ć19, GlossaryĆ6, GlossaĆ
ryĆ7
lengthof, 3Ć43
FFT mathwaveform, 3Ć36
acquisition mode, 3Ć45
aliasing, 3Ć46
Full, Display menu, 3Ć29
Full, Vertical menu, 3Ć138
Function, Cursor menu, 3Ć17, 3Ć18
Fuse, 1Ć4, 2Ć5
automated measurements of, 3Ć41
DC correction, 3Ć44
derivation of, 3Ć36
displaying phase, 3Ć38
frequency range, 3Ć43
frequency resolution, 3Ć43
interpolation mode, 3Ć45, 3Ć46
magnifying, 3Ć45
E
Edge trigger, 2Ć14, 3Ć32, GlossaryĆ3
Readout, 3Ć32, 3Ć76
Edge, Main Trigger menu, 3Ć32, 3Ć135
Edges, Measure Delay menu, 3Ć91
phase display, setup considerĆ
G
Either, Main Trigger menu, 3Ć112,
3Ć113
ations, 3Ć47ć3Ć52
phase suppression, 3Ć39, 3Ć48
procedure for displaying, 3Ć37
procedure for measuring, 3Ć40
record length, 3Ć43
reducing noise, 3Ć45
undersampling, 3Ć46
empty, Saved waveform status, 3Ć123
Gated Measurements, 3Ć88, GlossaĆ
ryĆ3
Encapsulated Postscript, 3Ć57
Gating, Measure menu, 3Ć88
Enter Char, Labelling menu, 3Ć54,
3Ć55
General purpose (high input resisĆ
tance) probes, 3Ć102
Envelope acquisition mode, 3Ć4,
GlossaryĆ3
zero phase reference, 3Ć47
General purpose knob, 1Ć20, 2Ć7,
GlossaryĆ4
FFT time domain record, defined, 3Ć42
Envelope, Acquire menu, 3Ć5
File System, 3Ć53ć3Ć56
Glitchtrigger, 3Ć109, 3Ć110, GlossaryĆ4
EPS Color Img, Hardcopy menu,
3Ć59
Optional File System, AĆ2
Glitch, Main Trigger menu, 3Ć111,
3Ć112
File Utilities menu, 3Ć53
Confirm Delete, 3Ć56
Copy, 3Ć55
EPS Color Plt, Hardcopy menu, 3Ć59
Goes FALSE, Main Trigger menu,
3Ć78
EPS Mono Img, Hardcopy menu,
3Ć59
Create Directory, 3Ć55
Delete, 3Ć54
File Utilities, 3Ć53
Format, 3Ć56
Overwrite Lock, 3Ć56
Print, 3Ć55
Goes TRUE, Main Trigger menu, 3Ć78
GPIB, 2Ć5, 3Ć116ć3Ć119, GlossaryĆ4
GPIB, Hardcopy menu, 3Ć59
EPS Mono Plt, Hardcopy menu, 3Ć59
Epson, 3Ć57
Epson, Hardcopy menu, 3Ć59
GPIB, Utility menu, 3Ć58, 3Ć118
Rename, 3Ć54
Graticule, 3Ć29, GlossaryĆ4
Measurements, 2Ć28
File Utilities, File Utilities menu, 3Ć53
F
Graticule, Display menu, 3Ć29
Grid, Display menu, 3Ć29
File Utilities, Save/Recall Setup
menu, 3Ć122
Factory initialization settings,
AĆ23ćAĆ28
File Utilities, Save/Recall Waveform
Ground coupling, GlossaryĆ4
menu, 3Ć125
factory, Saved setup status, 3Ć120
Filter, Display menu, 3Ć29
Fall time, 3Ć84, GlossaryĆ3
Fine Scale, Vertical menu, 3Ć138
Firmware version, 3Ć130
Falling edge, Delayed Trigger menu,
3Ć24
H
Fit to screen, Horizontal menu, 3Ć68
Fixtured active probes, 3Ć104
FORCE TRIG button, 3Ć133
Falling edge, Main Trigger menu, 3Ć34,
3Ć81
H Bars, Cursor menu, 3Ć17, 3Ć18
H Limit, Acquire menu, 3Ć71
Fast Fourier Transforms, description,
3Ć36
IndexĆ4
Index
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Index
Hamming window, 3Ć39
High speed active probes, 3Ć104
I
Hanning window, 3Ć39
High voltage probes, 3Ć103ć3Ć104
Hard Flagging, Utility menu, 3Ć58
Hardcopy, 3Ć57ć3Ć64, GlossaryĆ4
HighĆLow Setup, Measure menu,
3Ć89
I/O, Status menu, 3Ć130
I/O, Utility menu, 3Ć58, 3Ć118
Icons, 1Ć1
Histogram, Measure menu, 3Ć89
Hardcopy (Talk Only), Utility menu,
3Ć58
Holdoff, Main Trigger menu, 3Ć79,
3Ć111
Independent Mode, Cursor, 2Ć27ć2Ć28
HARDCOPY button, 3Ć53, 3Ć59, 3Ć118
Independent, Cursor menu, 3Ć18
Holdoff, trigger, 2Ć15, GlossaryĆ4
Horiz Pos, Horizontal menu, 3Ć68
Horiz Scale, Horizontal menu, 3Ć68
Hardcopy if Condition Met, Acquire
Infinite Persistence, Display menu,
3Ć27
menu, 3Ć73
Hardcopy Interface, Optional
Installation, 1Ć3ć1Ć4
RSĆ232/Centronic, AĆ2
Horizontal, 3Ć8
Integral math waveform, 3Ć143
applications, 3Ć143
Hardcopy menu
BMP Color, 3Ć59
BMP Mono, 3Ć59
Clear Spool, 3Ć59, 3Ć60
Deskjet, 3Ć59
Bar cursors, 2Ć27, 3Ć15, GlossaryĆ4
Control, 3Ć66ć3Ć69
Menu, 2Ć18
Position, 3Ć66
POSITION knob, 2Ć23
Readouts, 3Ć67
Scale, 3Ć66
SCALE knob, 1Ć11, 2Ć23
System, 1Ć11, 2Ć23
automated measurements of, 3Ć146
derivation of, 3Ć143
magnifying, 3Ć142, 3Ć147
procedure for displaying, 3Ć143
procedure for measuring, 3Ć144
record length of, 3Ć143
DPU411-II, 3Ć59
DPU412, 3Ć59
EPSColor Img , 3Ć59
EPSColor Plt , 3Ć59
EPSMono Img , 3Ć59
EPSMono Plt , 3Ć59
Epson, 3Ć59
Format, 3Ć59
GPIB, 3Ć59
HPGL, 3Ć59
Interleaf, 3Ć59
Landscape, 3Ć59
Laserjet, 3Ć59
Layout, 3Ć59
OK Confirm Clear Spool, 3Ć60
PCX, 3Ć59
PCX Color, 3Ć59
Port, 3Ć59
Portrait, 3Ć59
RLE Color, 3Ć59
Thinkjet, 3Ć59
Integration, Waveform, 3Ć143
Horizontal menu, 3Ć21
Intensified Samples, Display menu,
3Ć27
Delayed Only, 3Ć21
Delayed Runs After Main, 3Ć21,
3Ć68
Intensified, Horizontal menu, 3Ć21,
3Ć23
Delayed Scale, 3Ć68
Delayed Triggerable, 3Ć23, 3Ć68
Fit to screen, 3Ć68
Horiz Pos, 3Ć68
Horiz Scale, 3Ć68
Intensified, 3Ć21, 3Ć23
Main Scale, 3Ć68
Record Length, 3Ć68
Set to 10%, 3Ć68
Set to 50%, 3Ć68
Set to 90%, 3Ć68
Time Base, 3Ć21, 3Ć67
Trigger Position, 3Ć68
Intensity, 3Ć27, GlossaryĆ5
Intensity, Display menu, 3Ć27
Interleaf, 3Ć57
Interleaf, Hardcopy menu, 3Ć59
Interpolation, 2Ć20, 3Ć6, 3Ć29, GlossaĆ
ryĆ5
FFT distortion, 3Ć46
linear versus sin(x)/x, 3Ć46
IRE (NTSC), Cursor menu, 3Ć19
TIFF, 3Ć59
HORIZONTAL MENU button, 2Ć18,
3Ć21
Hardcopy, Color menu, 3Ć11
Hardcopy, Utility menu, 3Ć118
Hardware Setup, Utility menu, 3Ć58
HC100 Plotter, 3Ć57
K
Horizontal POSITION knob, 3Ć66
Horizontal Readouts, 3Ć67
Horizontal SCALE knob, 3Ć66
HPGL, 3Ć57
Keypad, 1Ć21
Knob, GlossaryĆ5
HC220 Printer, 3Ć57
General purpose, 1Ć20, 2Ć7, GlossaĆ
ryĆ4
HELP button, 3Ć65
HPGL, Hardcopy menu, 3Ć59
Hue, Color menu, 3Ć12
Horizontal POSITION, 1Ć11, 2Ć23,
3Ć66
Help system, 3Ć65
HF Rej, Main Trigger menu, 3Ć33
High, 3Ć84, GlossaryĆ4
High frequency rejection, 2Ć16
High Ref, Measure menu, 3Ć90
TDS 620A, 640A & 644A User Manual
IndexĆ5
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Index
Horizontal SCALE, 1Ć11, 2Ć23, 3Ć66
MEASURE, 2Ć26
Trigger MAIN LEVEL, 1Ć12, 2Ć17
Source, 3Ć32, 3Ć111, 3Ć113
State, 3Ć77, 3Ć81
Thresholds, 3Ć113
M
Main menu, GlossaryĆ5
Vertical POSITION, 1Ć11, 2Ć23,
3Ć136
Trigger When, 3Ć78, 3Ć80
True for less than, 3Ć80
True for more than, 3Ć80
Type, 3Ć32, 3Ć111, 3Ć113, 3Ć135
Width, 3Ć112
Main menu buttons, 2Ć3, GlossaryĆ5
Main Scale, Horizontalmenu, 3Ć68
Vertical SCALE, 1Ć11, 2Ć23, 3Ć136
Main Trigger Menu
Falling edge, 3Ć34
Rising edge, 3Ć34
MAIN TRIGGER OUTPUT, BNC, 2Ć5
Map Math, Color menu, 3Ć12
L
Main Trigger menu, 2Ć10, 3Ć32, 3Ć77,
Map Reference, Color menu, 3Ć13
3Ć111, 3Ć113, 3Ć135
AC, 3Ć33
Accept Glitch, 3Ć112
AND, 3Ć79, 3Ć82
Auto, 3Ć35, 3Ć79, 3Ć111
Labelling menu, Enter Char, 3Ć54,
3Ć55
Math Waveform
Differential, AĆ2
FFT, AĆ2
Landscape, Hardcopy menu, 3Ć59
Laserjet, 3Ć57
Integral, AĆ2
OptionalAdvanced, AĆ2
Ch1, Ch2 ..., 3Ć32, 3Ć78, 3Ć79, 3Ć81,
Laserjet, Hardcopy menu, 3Ć59
Layout, Hardcopy menu, 3Ć59
Level, Delayed Trigger menu, 3Ć24
3Ć111, 3Ć113
Class, 3Ć77, 3Ć111, 3Ć113
Coupling, 3Ć33
Math waveform
derivative. See Derivative math
waveform
DC, 3Ć33
FFT. See FFT math waveform
integral. See Integral math waveĆ
form
Level, Main Trigger menu, 3Ć34,
Define Inputs, 3Ć79, 3Ć81
Define Logic, 3Ć79, 3Ć82
Edge, 3Ć32, 3Ć135
3Ć112, 3Ć115
Level, Trigger, 2Ć17
Math waveforms, 3Ć148
Math, Color menu, 3Ć12
Math1/2/3, More menu, 3Ć148
Maximum, 3Ć84, GlossaryĆ5
Mean, 3Ć84, GlossaryĆ6
MEASURE button, 3Ć86
Either, 3Ć112, 3Ć113
Falling edge, 3Ć81
Glitch, 3Ć111, 3Ć112
Goes FALSE, 3Ć78
Goes TRUE, 3Ć78
LF Rej, Main Trigger menu, 3Ć33
Lightness, Color menu, 3Ć12
Limit Test Condition Met, Acquire
menu, 3Ć73
HF Rej, 3Ć33
Limit Test Setup, Acquire menu, 3Ć72,
3Ć73
Holdoff, 3Ć79, 3Ć111
Level, 3Ć34, 3Ć112, 3Ć115
LF Rej, 3Ć33
Mode & Holdoff, 3Ć35, 3Ć79, 3Ć111
NAND, 3Ć79, 3Ć82
Limit Test Sources, Acquire menu,
3Ć72
Measure Delay menu
Create Measrmnt, 3Ć92
Delay To, 3Ć90
Limit Test, Acquire menu, 3Ć73
Negative, 3Ć112, 3Ć113
Noise Rej, 3Ć33
NOR, 3Ć79, 3Ć82
Normal, 3Ć35, 3Ć79, 3Ć111
OR, 3Ć79, 3Ć82
Pattern, 3Ć77
Edges, 3Ć91
Measure Delay To, 3Ć90
OK Create Measurement, 3Ć92
Limit testing, 3Ć70ć3Ć74
Linear interpolation, 2Ć20, 3Ć29, GlosĆ
saryĆ5
Measure Delay To, Measure Delay
Linear interpolation, Display menu,
3Ć29
menu, 3Ć90
Measure menu, 2Ć10, 3Ć86, 3Ć93
Gating, 3Ć88
Polarity, 3Ć113
Logic trigger, 2Ć14, 3Ć77
Definitions, 3Ć77
Polarity and Width, 3Ć112
Positive, 3Ć112, 3Ć113
Pulse, 3Ć111, 3Ć113, 3Ć135
Reject Glitch, 3Ć112
Rising edge, 3Ć81
High Ref, 3Ć90
HighĆLow Setup, 3Ć89
Histogram, 3Ć89
Low Ref, 3Ć90
Mid Ref, 3Ć90
Mid2 Ref, 3Ć90
MinĆMax, 3Ć89
Reference Levels, 3Ć89
Remove Measrmnt, 3Ć87, 3Ć93
Select Measrmnt, 3Ć86, 3Ć90
Pattern, 3Ć76, GlossaryĆ5
State, 3Ć76, GlossaryĆ5
Logic triggering, 3Ć75ć3Ć82
Logic, Main Trigger menu, 3Ć135
Low, 3Ć84, GlossaryĆ5
Runt, 3Ć113
Set Thresholds, 3Ć78
Set to 50%, 3Ć34, 3Ć113, 3Ć133
Set to ECL, 3Ć34, 3Ć112
Set to TTL, 3Ć34, 3Ć112
Slope, 3Ć34
Low frequency rejection, 2Ć16
Low impedance Zo probes, 3Ć102
Low Ref, Measure menu, 3Ć90
IndexĆ6
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Index
Set Levels in % units, 3Ć89
Snapshot, 3Ć93
Main, 2Ć6
Main Trigger, 2Ć10, 3Ć32, 3Ć77,
3Ć111, 3Ć113, 3Ć135
Measure, 2Ć10, 3Ć86, 3Ć93
More, 2Ć10, 3Ć37, 3Ć124, 3Ć139,
3Ć148
See also More menu
Set FFTVert Scale to: , 3Ć38
Set FFTWindow to: , 3Ć38
Set Function to, 3Ć149
Set Function to:, 3Ć140, 3Ć144
Set operator to, 3Ć150
Set Single Source to, 3Ć149
Set Single Source to:, 3Ć139,
3Ć143
Measurement
Amplitude, 3Ć83, GlossaryĆ1
Area, 3Ć83, GlossaryĆ1
Burst width, 3Ć83, GlossaryĆ2
Cycle area, 3Ć83, GlossaryĆ3
Cycle mean, 3Ć83, GlossaryĆ3
Cycle RMS, 3Ć83, GlossaryĆ3
Delay, 3Ć90, GlossaryĆ3
Operation, 2Ć7
PopĆup, 2Ć8, GlossaryĆ7
Pulse trigger, 2Ć10
Single Wfm Math, 3Ć139, 3Ć143,
3Ć149
Save/Recall, 3Ć120
Duty cycle, 1Ć19, GlossaryĆ6, GlosĆ
saryĆ7
Save/Recall Setup, 2Ć10
Save/Recall Waveform, 2Ć10, 3Ć123
Setup, 1Ć8
Status, 2Ć10, 3Ć130ć3Ć131
Utility, 2Ć11, 3Ć58, 3Ć118
Fall time, 3Ć84
Frequency, 1Ć19, 3Ć84, GlossaryĆ3
Gated, GlossaryĆ3
High, 3Ć84, GlossaryĆ4
Low, 3Ć84, GlossaryĆ5
N
NAND, GlossaryĆ6
Mid Ref, Measure menu, 3Ć90
Mid2 Ref, Measure menu, 3Ć90
MinĆMax, Measure menu, 3Ć89
Minimum, 3Ć84, GlossaryĆ6
Mode, Cursor, 2Ć27ć2Ć28
NAND, Main Trigger menu, 3Ć79, 3Ć82
Negative duty cycle, 3Ć84
Negative overshoot, 3Ć84
Negative width, 3Ć84
Maximum, 3Ć84, GlossaryĆ5
Mean, 3Ć84, GlossaryĆ6
Minimum, 3Ć84, GlossaryĆ6
Negative duty cycle, 3Ć84
Negative overshoot, 3Ć84
Negative width, 3Ć84
Overshoot, GlossaryĆ7
Peak to peak, 3Ć84, GlossaryĆ6
Period, 3Ć85, GlossaryĆ6
Phase, 3Ć84, GlossaryĆ7
Positive duty cycle, 3Ć85
Positive overshoot, 3Ć85
Positive width, 3Ć85
Negative, Main Trigger menu, 3Ć112,
3Ć113
Mode & Holdoff, Main Trigger menu,
3Ć35, 3Ć79, 3Ć111
No Process, More menu, 3Ć149
Mode, Acquire menu, 3Ć5
Noise
Model number location, 2Ć3
Monochrome, Color menu, 3Ć11
reducing in FFTs, 3Ć45
reducing in phase FFTs, 3Ć39, 3Ć48
MORE button, 3Ć72, 3Ć124, 3Ć126,
3Ć148
Noise Rej, Main Trigger menu, 3Ć33
NOR, GlossaryĆ6
Propagation delay, 3Ć84
Readout, 3Ć86
More menu, 2Ć10, 3Ć124, 3Ć139, 3Ć148
Average, 3Ć149
Reference levels, 1Ć20
Rise time, 1Ć19, 3Ć85, GlossaryĆ8
RMS, 3Ć85, GlossaryĆ8
Undershoot, GlossaryĆ6
Width, 1Ć19, GlossaryĆ6, GlossaryĆ7
NOR, Main Trigger menu, 3Ć79, 3Ć82
Normal trigger mode, 2Ć14, GlossaryĆ6
Normal, Color menu, 3Ć11
BlackmanĆHarris, 3Ć39
Change Math waveform definiĆ
tion, 3Ć38, 3Ć139, 3Ć143, 3Ć149
dBV RMS, 3Ć38
diff, 3Ć140
Dual Wfm Math, 3Ć149
FFT, 3Ć38
Hamming, 3Ć39
Hanning, 3Ć39
intg, 3Ć144
Linear RMS, 3Ć38
Math1, Math2, Math3, 3Ć37, 3Ć139,
3Ć143
Normal, Main Trigger menu, 3Ć35,
3Ć79, 3Ć111
Measurement Accuracy, Ensuring
maximum, 3Ć94ć3Ć99,
3Ć128ć3Ć129
NTSC, Display menu, 3Ć29
Nyquist frequency, 3Ć46
Measurements, 2Ć26ć2Ć28, 3Ć83ć3Ć93
Algorithms, AĆ7ćAĆ20
Automated, 1Ć18, 2Ć26
Cursor, 2Ć27, 3Ć15
Gated, 3Ć88
Graticule, 2Ć28
Snapshot of, 3Ć92
O
Math1/2/3, 3Ć148
No Process, 3Ć149
OK Create Math Waveform,
3Ć144, 3Ć149
Phase (deg), 3Ć38
Phase (rad), 3Ć38
Rectangular, 3Ć38
Reference waveform status, 3Ć124
Set 1st Source to, 3Ć150
Set 2nd Source to, 3Ć150
Set FFTSource to: , 3Ć38
Off Bus, Utility menu, 3Ć118
Memory, Waveform, 3Ć124
Offset
Menu
DC. See DC Offset
Vertical, 2Ć23, 3Ć138
vertical, 3Ć44, 3Ć141, 3Ć146
Acquire, 3Ć5, 3Ć70
Color, 3Ć10
Cursor, 3Ć17
Delayed Trigger, 3Ć23ć3Ć25
Display, 3Ć10, 3Ć26
File Utilities, 3Ć53
Horizontal, 2Ć18, 3Ć21
Offset, Vertical menu, 3Ć138
OK Confirm Clear Spool, Hardcopy
menu, 3Ć60
TDS 620A, 640A & 644A User Manual
IndexĆ7
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Index
OK Create Math Wfm, More menu,
3Ć149
Plotter, HC100, 3Ć57
Low impedance Zo, 3Ć102
Optical, 3Ć106
Passive, 3Ć100
Polarity and Width, Main Trigger
OK Create Measurement, Measure
menu, 3Ć112
Passive voltage, 3Ć102ć3Ć103
Selection, 3Ć102ć3Ć108
TimeĆtoĆvoltage converter, 3Ć106
Delay menu, 3Ć92
Polarity, Main Trigger menu, 3Ć113
PopĆup menu, 2Ć8, GlossaryĆ7
Port, Hardcopy menu, 3Ć59
OK Erase Ref & PanelMemory ,
Utility menu, 3Ć121
Propagation delay, 3Ć84
Pulse trigger, 2Ć14, 3Ć109
Pulse Trigger menu, 2Ć10
OK Store Template, Acquire menu,
3Ć71
Port, Utility menu, 3Ć58, 3Ć118
Portrait, Hardcopy menu, 3Ć59
ON/STBY button, 1Ć5, 2Ć3
Optical probes, 3Ć106
Pulse, Main Trigger menu, 3Ć111,
Position
3Ć113, 3Ć135
Vertical, 2Ć23, 3Ć136
vertical, 3Ć44, 3Ć141, 3Ć146
Options, AĆ1ćAĆ6
Options, Color menu, 3Ć14
OR, GlossaryĆ6
Position, Vertical menu, 3Ć138
Positive duty cycle, 3Ć85
Positive overshoot, 3Ć85
Positive width, 3Ć85
OR, Main Trigger menu, 3Ć79, 3Ć82
Oscilloscope, GlossaryĆ6
Overall, Display menu, 3Ć27
Overshoot, GlossaryĆ7
Q
Quantizing, GlossaryĆ7
Positive, Main Trigger menu, 3Ć112,
3Ć113
Overwrite Lock, File Utilities menu,
3Ć56
Postscript, 3Ć57
R
Posttrigger, GlossaryĆ7
Power connector, 1Ć4, 2Ć5
Power cords, AĆ1
Rack mounting, AĆ2
Readout
P
Power off, 1Ć6
Acquisition, 3Ć5
Power on, 1Ć5
Channel, 2Ć6, 3Ć126
Cursors, 2Ć6
P6205 Active Probe, 1Ć3
Packaging, AĆ21
Pretrigger, GlossaryĆ7
Principal power switch, 1Ć5, 2Ć5
Print, File Utilities menu, 3Ć55
Edge trigger, 3Ć32, 3Ć76
General purpose knob, 2Ć6
Measurement, 2Ć27, 3Ć86
Record view, 2Ć6
Snapshot, 3Ć92
Paired cursor, 2Ć27, 3Ć15
PAL, Display menu, 3Ć29
Palette, Color menu, 3Ć11
Parity, Utility menu, 3Ć58
Passive voltage probes, 3Ć102ć3Ć103
Pattern trigger, 3Ć75, 3Ć79
Pattern, Main Trigger menu, 3Ć77
PCX, 3Ć57
Printer
HC220, 3Ć57
Phaser, 3Ć57
Time base, 2Ć6
Trigger, 2Ć6, 3Ć134
Trigger Level Bar, 3Ć28
Trigger Point, 3Ć28
Probe Cal, 3Ć94ć3Ć99
Probes
Accessories, AĆ4ćAĆ6
Active voltage, 3Ć104ć3Ć105
Additional, AĆ3
By applications, 3Ć107, 3Ć108
Compensation, 1Ć11, 3Ć100, GlosĆ
saryĆ7
Readout, Cursor, Paired, 3Ć141
Readout, cursor
HĆBars, 3Ć40, 3Ć141, 3Ć145
Paired cursors, 3Ć41, 3Ć145
VĆBars, 3Ć40, 3Ć141, 3Ć145
PCX Color, Hardcopy menu, 3Ć59
PCX, Hardcopy menu, 3Ć59
Peak to peak, 3Ć84, GlossaryĆ6
Period, 3Ć85, GlossaryĆ6
Persistence, 3Ć27
Connection, 1Ć7
Current, 3Ć105
Readout, Display menu, 3Ć28
RealĆtime sampling, GlossaryĆ8
Rear panel, 2Ć5, 3Ć118
Definition, GlossaryĆ7
Delete Four Option, AĆ2
Delete Two Option, AĆ2
Differential active, 3Ć104
Fixtured active, 3Ć104
General purpose (high input resisĆ
tance), 3Ć102
High speed, 3Ć104
Recall, Setups, 3Ć120ć3Ć122
Persistence Palette, Color menu,
3Ć11
Recall Factory Setup, Save/Recall
Setup menu, 3Ć121
Phase, 3Ć84, GlossaryĆ7
Phase suppression, 3Ć48
Phaser Color Printer, 3Ć57
Pixel, GlossaryĆ7
Recall Saved Setup, Save/Recall
Setup menu, 3Ć121
High voltage, 3Ć103ć3Ć104
IndexĆ8
Index
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Index
Recalling, Waveforms, 3Ć123
Runt trigger, 3Ć109, 3Ć110, 3Ć113,
GlossaryĆ8
Select Measrmnt, Measure menu,
3Ć86, 3Ć90
Record length, 1Ć1, 2Ć19, 3Ć68, GlossaĆ
ryĆ8
Runt, Main Trigger menu, 3Ć113
Selected waveform, GlossaryĆ8
Selectingchannels, 3Ć126
Self test, 1Ć6
derivative math waveforms, 3Ć139
integral math waveforms, 3Ć143
Record Length, Horizontal menu,
3Ć68
Serial number, 2Ć5
S
Set 1st Source to, More menu, 3Ć150
Record View, 2Ć6, 2Ć22, 3Ć67, 3Ć134
Rectangular window, 3Ć38
Ref, Color menu, 3Ć13
Set 2nd Source to, More menu,
3Ć150
Safety, xi
Symbols, xi
Set Function to, More menu, 3Ć149
Sample acquisition mode, 3Ć3, GlosĆ
saryĆ8
Ref1, Ref2, Ref3, Ref4, File, Save/
SET LEVEL TO 50% button, 3Ć133
Recall Waveform menu, 3Ć124
Sample interval, GlossaryĆ8
Sample, Acquire menu, 3Ć5
Sampling, 2Ć20, GlossaryĆ8
Saturation, Color menu, 3Ć12
Save, Setups, 3Ć120ć3Ć122
Set Levels in % units, Measure
Ref1, Ref2, Ref3, Ref4, Reference
menu, 3Ć89
waveform status, 3Ć124
Set operator to, More menu, 3Ć150
Reference levels, 1Ć20, 3Ć89
Set Single Source to, More menu,
3Ć149
Reference Levels, Measure menu,
3Ć89
Set Thresholds, Main Trigger menu,
3Ć78
Reference memory, GlossaryĆ8
Save Current Setup, Save/Recall
Reject Glitch, Main Trigger menu,
3Ć112
Setup menu, 3Ć120
Set to 10%, Horizontal menu, 3Ć68
Save Waveform, Save/Recall WaveĆ
Set to 50%, Delayed Trigger menu,
3Ć25
Remote communication, 3Ć116ć3Ć119
form menu, 3Ć123
Remove Measrmnt, Measure menu,
Save/Recall SETUP button, 1Ć8, 3Ć53,
3Ć120
Set to 50%, Horizontal menu, 3Ć68
3Ć87, 3Ć93
Set to 50%, Main Trigger menu, 3Ć34,
Rename, File Utilities menu, 3Ć54
Save/Recall Setup menu, 2Ć10, 3Ć120
factory status, 3Ć120
3Ć113, 3Ć133
Reset All Mappings To Factory,
File Utilities, 3Ć122
Set to 90%, Horizontal menu, 3Ć68
Color menu, 3Ć14
Recall Factory Setup, 3Ć121
Recall Saved Setup, 3Ć121
Save Current Setup, 3Ć120
user status, 3Ć120
Set to ECL, Delayed Trigger menu,
3Ć24
Reset All Palettes To Factory, Color
menu, 3Ć14
Set to ECL, Main Trigger menu, 3Ć34,
3Ć112
Reset Current Palette To Factory,
Color menu, 3Ć14
Save/Recall WAVEFORM button,
Set to TTL, Delayed Trigger menu,
3Ć24
Reset to Factory Color, Color menu,
3Ć12
3Ć53, 3Ć123
Save/Recall Waveform menu, 2Ć10,
3Ć123
Set to TTL, Main Trigger menu, 3Ć34,
3Ć112
Reset Zoom Factors, Zoom menu,
3Ć153
active status, 3Ć123
Set to Zero, Vertical menu, 3Ć138
SettingUp for the Examples, 1Ć7
Settings, Display menu, 3Ć10, 3Ć26
Setup menu, 1Ć8
Autosave, 3Ć125
Delete Refs, 3Ć124
empty status, 3Ć123
File Utilities, 3Ć125
Ref1, Ref2, Ref3, Ref4, File, 3Ć124
Save Waveform, 3Ć123
Restore Colors, Color menu, 3Ć14
Ring Bell if Condition Met, Acquire
menu, 3Ć73
Rise time, 1Ć19, 3Ć85, GlossaryĆ8
Rising edge, Delayed Trigger menu,
3Ć24
Setups, Save and recall, 3Ć120ć3Ć122
Shipping, AĆ21
Saving, Waveforms, 3Ć123
Rising edge, Main Trigger menu, 3Ć34,
3Ć81
Savingand recallingsetups, 1Ć24,
3Ć120
Side menu, GlossaryĆ9
RLE Color, Hardcopy menu, 3Ć59
RMS, 3Ć85, GlossaryĆ8
RSĆ232, 2Ć5
Side menu buttons, 2Ć3, GlossaryĆ9
SIGNAL OUTPUT, BNC, 2Ć5
Savingand recallingwaveforms,
3Ć123
Scale, vertical, 3Ć44, 3Ć141, 3Ć146
Signal Path Compensation, 1Ć3,
3Ć128ć3Ć129
seconds, Cursor menu, 3Ć19
RSĆ232, Port, 3Ć59
Sin(x)/x interpolation, 2Ć20, 3Ć29,
GlossaryĆ5
SELECT button, 2Ć27, 3Ć18, GlossaĆ
ryĆ8
RS232, Utility menu, 3Ć58
RUN/STOP, Acquire menu, 3Ć6
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Sin(x)/x interpolation, Display menu,
3Ć29
Slope, 2Ć13, 2Ć17
Source, 2Ć13
State, 3Ć81
Status Lights, 3Ć133
Types, 3Ć135
Video, 2Ć14
T
Single Acquisition Sequence,
Talk/Listen Address, Utility menu,
3Ć118
Acquire menu, 3Ć7
SINGLE TRIG button, 3Ć7, 3Ć133
Single Wfm Math, More menu, 3Ć149
Slope, GlossaryĆ9
Tek Secure, 3Ć121, GlossaryĆ9
Width, 3Ć109, 3Ć115
Tek Secure Erase Memory, Utility
Trigger Bar, 2Ć6
menu, 3Ć121
Slope, Delayed Trigger menu, 3Ć24
Slope, Main Trigger menu, 3Ć34
Slope, Trigger, 2Ć17
Trigger Bar Style, Display menu, 3Ć28
Trigger Level Bar, Readout, 3Ć28
Temperature compensation,
3Ć128ć3Ć129
Temperature, Color menu, 3Ć11
Trigger MAIN LEVEL knob, 1Ć12, 2Ć17,
3Ć132
Template Source, Acquire menu,
3Ć70
Snapshot, Readout, 3Ć92
TRIGGER MENU button, 3Ć32, 3Ć77,
Snapshot of Measurements, 1Ć22,
3Ć92
3Ć111, 3Ć113, 3Ć135
Text/Grat, Display menu, 3Ć27
Thinkjet, 3Ć57
Trigger Point, Readout, 3Ć28
Snapshot, Measure menu, 3Ć93
Soft Flagging, Utility menu, 3Ć58
Software, 1Ć1
Trigger Position, Horizontal menu,
3Ć68
Thinkjet, Hardcopy menu, 3Ć59
Thresholds, Main Trigger menu,
3Ć113
Trigger Status Lights, 3Ć133
Software Setup, Utility menu, 3Ć58
Software version, 3Ć130
Trigger When, Main Trigger menu,
TIFF, 3Ć57
3Ć78, 3Ć80
TIFF, Hardcopy menu, 3Ć59
Time base, GlossaryĆ9
Trigger, Status menu, 3Ć130
Source, Delayed Trigger menu, 3Ć24
True for less than, Main Trigger
Source, Main Trigger menu, 3Ć32,
Time Base, Horizontal menu, 3Ć21,
3Ć67
menu, 3Ć80
3Ć111, 3Ć113
True for more than, Main Trigger
Spectral, Color menu, 3Ć11
Spooler, Hardcopy, 3Ć60
Start up, 1Ć3
Time Units, Cursor menu, 3Ć19
TimeĆtoĆvoltage converter, 3Ć106
TOGGLE button, 3Ć18
menu, 3Ć80
Type, Main Trigger menu, 3Ć32, 3Ć111,
3Ć113, 3Ć135
State trigger, 3Ć81
TrackingMode, Cursor, 2Ć28
Tracking, Cursor menu, 3Ć18
State, Main Trigger menu, 3Ć77, 3Ć81
STATUS button, 3Ć130
Trigger, 2Ć13ć2Ć18, 3Ć8, GlossaryĆ9
AC Line Voltage, 2Ć14
Auxiliary, 2Ć14
U
Status menu, 2Ć10, 3Ć130ć3Ć131
Display, 3Ć130
Undershoot, GlossaryĆ6
user, Saved setup status, 3Ć120
UTILITY button, 3Ć58, 3Ć118
Utility Menu
Firmware version, 3Ć130
I/O, 3Ć130
System, 3Ć130
Trigger, 3Ć130
Waveforms, 3Ć130
Coupling, 2Ć16
Delay, 2Ć18
Delayed, 3Ć20ć3Ć25
Edge, 2Ć14, 3Ć32, GlossaryĆ3
Glitch, 3Ć109, 3Ć110, GlossaryĆ4
Holdoff, 2Ć15
Level, 2Ć17, GlossaryĆ9
Logic, 2Ć14, 3Ć75ć3Ć82
Mode, 2Ć14
Pattern, 3Ć75, 3Ć79
Position, 2Ć17, 3Ć68
Pulse, 2Ć14, 3Ć109
Readout, 3Ć134
Runt, 3Ć109, 3Ć110, 3Ć113, GlossaĆ
ryĆ8
OK Erase Ref & Panel Memory,
3Ć121
Stop After Limit Test Condition Met,
Acquire menu, 3Ć73
Tek Secure Erase Memory, 3Ć121
Stop After, Acquire menu, 3Ć6, 3Ć73
Stop Bits, Utility menu, 3Ć58
Style, Display menu, 3Ć26
Utility menu, 2Ć11, 3Ć58, 3Ć118
BaudRate , 3Ć58
Configure, 3Ć58, 3Ć118
GPIB, 3Ć58, 3Ć118
HardFlagging , 3Ć58
Hardcopy, 3Ć118
Switch, principal power, 1Ć5, 2Ć5
System, Status menu, 3Ć130
System, Utility menu, 3Ć58, 3Ć118
IndexĆ10
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Index
Hardcopy (Talk Only), 3Ć58
Hardware Setup, 3Ć58
I/O, 3Ć58, 3Ć118
Vertical Readout, 3Ć136
Vertical SCALE knob, 3Ć136
VGA Output, 2Ć5
characteristics of, 3Ć51
Hamming, 3Ć39, 3Ć49, 3Ć52
Hanning, 3Ć39, 3Ć49, 3Ć52
rectangular, 3Ć38, 3Ć49, 3Ć52
Off Bus, 3Ć118
Parity, 3Ć58
Port, 3Ć58, 3Ć118
rectangular vs. bellĆshaped, 3Ć51
selecting, 3Ć49
Video Line Number, Cursor menu,
3Ć19
RS232, 3Ć58
Windowing, process, 3Ć49
Video Trigger, Option 5, AĆ2
Video trigger, 2Ć14
Soft Flagging, 3Ć58
Software Setup, 3Ć58
Stop Bits, 3Ć58
Windows, descriptions of, 3Ć38ć3Ć39
View Palette, Color menu, 3Ć11
System, 3Ć58, 3Ć118
Talk/Listen Address, 3Ć118
X
W
XY, Format, 3Ć29ć3Ć31
XY format, GlossaryĆ9
XY, Display menu, 3Ć30
V
WARNING, statement in manual, xi
Waveform, GlossaryĆ9
Interval, GlossaryĆ9
Math, 3Ć148ć3Ć150
Off priority, 3Ć127
V Limit, Acquiremenu, 3Ć71
Variable Persistence, Display menu,
3Ć27
Vectors, 3Ć27
Waveform clipping. See Clipping
Waveform differentiation, 3Ć139
Waveform FFTs, 3Ć36
Y
Vectors, Display menu, 3Ć27
Vertical, 3Ć8
YT, Format, 3Ć29ć3Ć31
YT format, GlossaryĆ9
YT, Display menu, 3Ć30
Bar cursors, 2Ć27, 3Ć15, GlossaryĆ9
Control, 3Ć136ć3Ć138
Offset, 2Ć23, 3Ć138
Position, 2Ć23, 3Ć136
POSITION knob, 2Ć23
Readout, 3Ć136
Scale, 3Ć136
SCALE knob, 1Ć11, 2Ć23
System, 1Ć11, 2Ć23
Waveform integration, 3Ć143
Waveform memory, 3Ć124
WAVEFORM OFF button, 1Ć17, 3Ć30,
3Ć127
Waveform record
Z
FFT, 3Ć42
FFT frequency domain, 3Ć42
length of, 3Ć42
FFT source, 3Ć42
Zero phase reference point, 3Ć42, 3Ć47
Vertical Menu, Cal Probe, 3Ć94
establishing for impulse testing,
3Ć47ć3Ć52
acquisition mode, 3Ć45
defined, 3Ć42
long versus short, 3Ć45
Vertical menu
100 MHz, 3Ć138
20 MHz, 3Ć138
Bandwidth, 3Ć138
Coupling, 3Ć137
Fine Scale, 3Ć138
Full, 3Ć138
Offset, 3Ć138
Position, 3Ć138
Set to Zero, 3Ć138
Zoom, 3Ć151ć3Ć154
derivative math waveforms, 3Ć142
on FFT math waveforms, 3Ć45
on integral math waveforms, 3Ć147
FFT timedomain, 3Ć42ć3Ć52
Waveform, Display menu, 3Ć27
Waveforms, Math, 3Ć148
ZOOM button, 3Ć151
Waveforms, Status menu, 3Ć130
Width, 1Ć19, GlossaryĆ6, GlossaryĆ7
Width trigger, 3Ć109, 3Ć115
Zoom feature, 2Ć25
Zoom menu
Reset Zoom Factors, 3Ć153
Zoom Off, 3Ć153
VERTICAL MENU button, 1Ć15
Width, Main Trigger menu, 3Ć112
Vertical position, for DC correction of
Zoom Off, Zoom menu, 3Ć153
Window, 3Ć49
FFTs, 3Ć44
BlackmanĆHarris, 3Ć39, 3Ć49, 3Ć52
Vertical POSITION knob, 3Ć136
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IndexĆ12
Index
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