Agilent Technologies Stereo System Agilent 35670A User Manual

Supplemental Operator’s Guide  
for the Agilent 35670A Dynamic Signal Analyzer  
By:  
David Forrest  
Seattle Sound and Vibration, inc.  
Print Date: December, 2000  
ãSeattle Sound and Vibration, inc. 1996, 2000.  
All rights reserved.  
Agilent Part number 35670-90059  
Special Permission Amoco Corporation and Agilent Technologies, Inc are granted  
full editing, duplication and distribution privileges.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
SECTION 11 : MODAL TESTING USING A HAMMER AND ACCELEROMETER................................. 25  
SETTING UP THE TRANSDUCER PARAMETERS......................................................................................................... 25  
SETTING UP INPUT RANGE...................................................................................................................................... 26  
CHOOSING A PRELIMINARY FREQUENCY SPAN....................................................................................................... 26  
SPECIFYING TRIGGER PARAMETERS ....................................................................................................................... 26  
SETTING UP TIME DISPLAYS................................................................................................................................... 27  
USING FORCE/RESPONSE WINDOWS ....................................................................................................................... 28  
DISPLAYING HAMMER TEST RESULTS .................................................................................................................... 29  
AVERAGING ............................................................................................................................................................ 29  
CHANGING FREQUENCY SPAN ................................................................................................................................ 31  
SECTION 12 : HAMMER TEST SETUP WITHOUT A FORCE TRANSDUCER........................................ 32  
SETTING UP THE HAMMER TEST WITHOUT A FORCE TRANSDUCER ....................................................................... 32  
SECTION 13 : ORDER DOMAIN RESULTS IN LIST MODE........................................................................ 33  
SECTION 14 : COMPARING TWO-CHANNEL REAL-TIME SPECTRA WITH RECALLED DATA.... 35  
SELECTING MEASUREMENT PARAMETERS.............................................................................................................. 35  
DISPLAYING DUAL-CHANNEL SPECTRA COMPARED WITH RECALLED DATA ......................................................... 35  
RECALLING THE SPECTRA FROM DISK .................................................................................................................... 36  
RECALLING THE SPECTRA FROM NON-VOLATILE RAM ......................................................................................... 36  
SCALING THE DISPLAYS.......................................................................................................................................... 37  
USING MARKERS TO COMPARE............................................................................................................................... 38  
SECTION 15 : WATERFALL SPECTRA AT TIME INTERVALS ................................................................ 39  
SELECTING SINGLE CHANNEL OPERATION ............................................................................................................. 39  
SELECTING MEASUREMENT PARAMETERS.............................................................................................................. 39  
SETTING UP THE WATERFALL DISPLAY.................................................................................................................. 39  
SETTING UP TIME STEP ARM .................................................................................................................................. 40  
USING SLICE MARKERS WITH WATERFALL DATA .................................................................................................. 40  
COLLECTING A SPECIFIED NUMBER OF SPECTRA DURING A TIME INTERVAL ......................................................... 41  
SECTION 16 : WATERFALL SPECTRA AT RPM INTERVALS.................................................................. 42  
SETTING UP THE TACHOMETER .............................................................................................................................. 42  
SPECIFYING THE START RPM ................................................................................................................................. 42  
COLLECTING A SPECIFIED NUMBER OF SPECTRA DURING AN RPM INTERVAL....................................................... 42  
STARTING AND PAUSING A MEASUREMENT............................................................................................................ 43  
SCALING THE DISPLAY............................................................................................................................................ 43  
SECTION 17 : 2-CHANNEL ABSOLUTE AND DIFFERENTIAL AMPLITUDE MEASUREMENT ....... 45  
ACCELEROMETER POLARITY................................................................................................................................... 45  
MEASURING AMPLITUDES, DIFFERENTIAL AMPLITUDE, AND PHASE...................................................................... 46  
USING A MATH FUNCTION TO MEASURE DIFFERENTIAL MOTION .......................................................................... 47  
SECTION 18 : MEASURING FREQUENCY RESPONSE WITH THE AGILENT 35670A ........................ 50  
MEASURING FREQUENCY RESPONSE USING IMPACT EXCITATION.......................................................................... 50  
MEASURING FREQUENCY RESPONSE USING BROADBAND EXCITATION ................................................................. 50  
VIEWING FREQUENCY RESPONSE RESULTS WITH A NYQUIST DIAGRAM ................................................................ 53  
VIEWING RESULTS USING REAL AND IMAGINARY TRACES .................................................................................... 54  
ASSESSING MEASUREMENT QUALITY..................................................................................................................... 55  
SECTION 19 : TWO SPECTRAL TRACES SHOWING MILS AND IPS WHILE EU IS G........................ 56  
SECTION 20 : PEAK HOLD DURING A MACHINE RUN-UP AND COAST-DOWN................................ 58  
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AGILENT 35670A  
Supplemental Operator’s Guide  
SECTION 21 : USING AN EXTERNAL TRIGGER FOR TIME AVERAGING........................................... 60  
SPECIFY USER LEVELS FOR TRIGGERING ................................................................................................................ 60  
CHARACTERIZING THE EXTERNAL TRIGGER ........................................................................................................... 60  
SETTING UP EXTERNAL TRIGGER ........................................................................................................................... 61  
MEASURING TIME AVERAGED SPECTRUMS WITH EXTERNAL TRIGGERING............................................................. 62  
SECTION 22 : SAVING TRACE DATA TO A 3.5” DISK OR NON-VOLATILE RAM .............................. 63  
SAVING TRACE TO 3.5” DISK.................................................................................................................................. 63  
CONFIRMING CONTENTS OF 3.5” DISK FILE............................................................................................................ 63  
SAVING TRACE TO NON-VOLATILE RAM (NV-RAM)........................................................................................... 64  
CONFIRMING CONTENTS OF NV-RAM ................................................................................................................... 64  
SECTION 23 : RECALLING TRACE DATA FROM 3.5” DISK OR NON-VOLATILE MEMORY.......... 65  
RECALL TRACE FROM 3.5” DISK ............................................................................................................................ 65  
RECALL TRACE DATA FROM NON-VOLATILE RAM (NV-RAM)............................................................................ 65  
SECTION 24 : PLOTTING AND PRINTING TRACE DATA ......................................................................... 67  
GENERATING OUTPUT WITH THE AGILENT 35670A............................................................................................. 67  
PLOTTING THE DISPLAY.......................................................................................................................................... 67  
PRINTING THE DISPLAY........................................................................................................................................... 68  
SECTION 25 : IMPORTING PLOTS INTO MICROSOFT WORD................................................................ 69  
DETERMINING IF MS WORD HAS HP-GL GRAPHICS IMPORT FILTER..................................................................... 69  
INSTALLING THE MS WORD HP-GL GRAPHICS IMPORT FILTER............................................................................. 69  
PLOT TO A FILE USING THE AGILENT 35670A ..................................................................................................... 70  
INSERTING PICTURE OF AN HP-GL PLOT FILE INTO A MS WORD DOCUMENT. ...................................................... 70  
SECTION 26 : RUNNING A SINGLE CALIBRATION TEST ON COMMAND .......................................... 71  
SECTION 27 : RETURNING THE AGILENT 35670A TO A PRESET CONDITION.................................. 71  
SECTION 28 : PRECAUTIONS TO PREVENT LOSS OF DATA .................................................................. 71  
SECTION 29 : TRANSDUCER UNIT CONVERSION WITH THE AGILENT 35670A............................... 72  
MEASURING ACCELERATION, DISPLAYING DISPLACEMENT ................................................................................... 72  
MATH FUNCTIONS AND XDCR UNIT CONVERT................................................................................................. 73  
CONVERTING FREQUENCY RESPONSE UNITS TO COMPLIANCE ............................................................................... 73  
SECTION 30 : USING THE AGILENT DEMO UNIT WITH THE AGILENT 35670A................................ 75  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 1 : Turning On the AGILENT 35670A  
The entire turn-on procedure for the AGILENT 35670A takes 40 seconds. In  
that time the analyzer completes a hardware self-test, boots its operating system,  
completes a front end self-calibration and autoranges all input channels. The  
default measurement state of the analyzer is a two-channel FFT measurement  
with a span of 51.2 kHz, front ends autoranging, input low floating, and DC  
coupled, averaging OFF and with a power spectrum display.  
FFT  
ANALYSIS  
OCTAVE  
A: CH1 Pwr Spec  
X:0  
Hz  
Y:40.9385 uVrms  
ANALYSIS  
10  
mVrms  
ORDER  
ANALYSIS  
SWEPT  
SINE  
LogMag  
6
decades  
CORRELATN  
ANALYSIS  
HISTOGRAM  
/ TIME  
CHANNELS  
1
4
2
REF CHANS  
1,3  
1
TIME  
CAPTURE  
10  
nVrms  
0Hz  
51.2kHz  
Typical Display After Turn-on Sequence  
1
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 2 : Measurement State After Turn-on  
Inst Mode FFT  
Measurement Source  
Channels 2  
INPUT  
Meas Data Data A  
PWR SPEC1  
TIME1  
Data B  
Data D  
PWR SPEC2  
TIME2  
Data C  
Trac Coord Coord A MAG-LOG  
Coord B MAG-LOG  
Coord D REAL  
Coord C REAL  
Freq  
Start  
Center  
0 Hz  
25.6 kHz  
Stop  
Span  
51.2 kHz  
51.2 kHz  
Rec Len 7.8125 ms  
Resoltn 400  
Window  
CH1 Type FLATTOP  
CH2 Type FLATTOP  
CH3 Type FLATTOP  
CH4 Type FLATTOP  
BW  
BW  
BW  
BW  
488.88 Hz  
488.88 Hz  
488.88 Hz  
488.88 Hz  
Avg  
Status  
Number  
Fast Avg OFF  
OFF  
10  
Type  
RMS  
Overlap 0 %  
Update  
Ovld Rej OFF  
5
Rept Avg FREEZE  
Trigger  
Type  
Slope  
FREE-RUN  
POSITIVE  
Level  
0 V  
Ext Lvl 1.48 V  
Ext Fltr OFF  
CH1 Dlay 0 s  
CH3 Dlay 0 s  
CH2 Dlay 0 s  
CH4 Dlay 0 s  
Strt RPM 600 rpm  
Time Stp 500 ms  
RPM Dir UP  
Arm  
IMMEDIATE  
RPM Step 60 rpm  
Wtrfall 15  
Source  
Status  
Level  
Type  
OFF  
0 Vpk  
SINUSOID  
DC Offst 0 V  
Sine Frq 10.24 kHz  
Arb Reg D1  
Arb Fltr OFF  
Arb Rept ON  
Input  
Status  
Range  
CHANNEL 1  
ON  
CHANNEL 2  
ON  
CHANNEL 3  
OFF  
CHANNEL 4  
OFF  
3.9858 mVp 3.9858 mVp 3.9858 mVp 3.9858 mVp  
Auto Rng OFF  
Coupling DC  
InputLow FLOAT  
AliasFlt ON  
A WtFltr OFF  
OFF  
DC  
FLOAT  
ON  
OFF  
OFF  
DC  
FLOAT  
ON  
OFF  
OFF  
DC  
FLOAT  
ON  
OFF  
ICP  
OFF  
OFF  
OFF  
OFF  
EngrUnit OFF  
EU Label USER  
OFF  
USER  
1 V/EU  
OFF  
USER  
1 V/EU  
OFF  
USER  
1 V/EU  
EU Mult  
1 V/EU  
--- TACHOMETER ---  
Puls/Rev 1  
Level  
Range  
Slope  
0 V  
LOW  
POSITIVE  
Holdoff 0 s  
2
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 3 : Measuring with Transducers  
The AGILENT 35670A can be used with a broad range of transducers. Transducers  
can use an external preamplifier to convert the raw signal into a voltage that is  
compatible with the AGILENT 35670A. Some transducers have internal circuitry  
which provides preamplification, however these internal circuits must be powered  
externally. The AGILENT 35670A can provide the necessary constant-current  
supply for transducers that are of type ICP, Isotron, Piezotron, DelaTron, Low  
Impedance, etc.  
Using ICP-Type Transducers with the AGILENT 35670A  
To set up Channel 1 for an ICP-type transducer:  
Press the [Input] hardkey  
Press [FRONT END CH1 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Note that the analyzer automatically switches the front end to AC Coupling in order  
to reject the large DC signal that is generated by the constant-current supply.  
To set up Channel 2 for an ICP transducer:  
Press the [Input] hardkey  
Press [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press [FRONT END CH2 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
For AGILENT 35670A analyzers with four channels, these same procedures can be  
repeated for Channels 3 and 4.  
Using Transducers with External Preamplifiers  
No special front end setup is required to use transducers with external preamplifiers  
except if the preamplifier’s DC component is too high, resulting in a loss of dynamic  
range. This can be easily minimized by switching to AC coupling as follows:  
Press the [Input] hardkey  
Press [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press [FRONT END CH1 SETUP] softkey (F7).  
Press [COUPLING AC DC] softkey (F5) until AC is highlighted.  
A transducer with an external preamplifier will convert mechanical units (EU) to  
volts. Care must be taken to observe gain settings on the external preamplifier,  
because these gain settings directly affect the resulting transducer sensitivity.  
3
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AGILENT 35670A  
Supplemental Operator’s Guide  
For example, if an accelerometer has am internal sensitivity of 25 pC/g, and a charge  
amplifier has a gain setting of 10 mV/pC, then the resulting transducer sensitivity is  
250 mV/g. However is the gain setting on the charge amplifier is changed to 1  
mV/pC, then the resulting sensitivity would then be 25 mV/g.  
Specifying Transducer Sensitivity and Units  
The AGILENT 35670A provides the ability to convert electrical signals into  
Engineering Units. Units can be specified as either conventional units or User units.  
Conventional units of motion available are:  
acceleration:  
g, m/s^2, inch/s^2  
velocity:  
m/s, inch/s  
displacement: m, inch, mil  
force: N, lb., dyne  
To set up transducer properties for an accelerometer attached to Channel 2 with a  
sensitivity of 9.7 pC/g, follow these steps:  
Press [Input] hardkey.  
Press [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press [XDCR UNIT CH2 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 9.7, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Select the [g] softkey (F2).  
Likewise if a force transducer is attached to Channel 1 with a sensitivity of 12.2  
mV/lb., do the following:  
Press [Input] hardkey.  
Press [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press [XDCR UNIT CH1 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 12.2, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Press the [MORE CHOICES] softkey (F9).  
Select the [ lb ] softkey (F6).  
4
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 4 : Measuring a Single Channel Power Spectrum - Displacement  
This section contains procedures for setting up and measuring a single channel  
power spectrum of displacement using an AGILENT 35670A Dynamic Signal  
Analyzer. Included are steps to select single channel operation, set up transducer  
parameters, frequency span, choose input range, select windowing, and turn on  
averaging in order to improve measurement accuracy. Instructions will also be  
presented to set up trace coordinates and trace scaling.  
Selecting Single Channel Operation  
Specify the single-channel instrument mode to measure one signal. However it  
should be noted that it is acceptable to measure a single channel in the default two-  
channel instrument mode and simply ignore the second channel. Nevertheless  
instructions will be given here to measure in single channel mode.  
To measure a single-channel spectrum, turn on the AGILENT 35670A and then:  
Press the [Inst Mode] hardkey  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Setting Up Transducer Units for Displacement  
To measure power spectrums using a displacement transducer with a sensitivity of  
200 mV/mil, follow these steps:  
Press the [Input] hardkey.  
Enter 800 and then press the [Hz] softkey (F2).  
Any frequency below 51.2 kHz may of course be entered, however the analyzer will  
select the lowest span that contains the desired frequency. For example, if 1200 Hz  
is entered, the analyzer is switched to a span of 1600 Hz.  
Selecting Frequency Span  
The default frequency span after turn-on is 51.2 kHz, which is usually too high for  
most transducer measurements. To reduce the span to 800 Hz, perform the following  
steps:  
Press the [Freq] hardkey.  
Enter 800 and then press the [Hz] softkey (F2).  
5
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AGILENT 35670A  
Supplemental Operator’s Guide  
Any frequency below 51.2 kHz may of course be entered, however the analyzer will  
select the lowest span that contains the desired frequency. For example, if 1200 Hz  
is entered, the analyzer is switched to a span of 1600 Hz.  
Frequency Spans Available  
for the AGILENT 35670A  
102.4 kHz *  
51.2 kHz  
25.6 kHz  
12.8 kHz  
6.4 kHz  
3.2 kHz  
1.6 kHz  
800 Hz  
100 Hz  
50 Hz  
25 Hz  
12.5 Hz  
6.25 Hz  
3.125 Hz  
1.5625 Hz  
0.78125 Hz  
0.390625  
0.1953125 Hz  
400 Hz  
200 Hz  
* Available in single-channel mode when anti-alias filter is turned off.  
To begin data acquisition,  
Press the [Start] hardkey.  
To automatically scale the display to fit the data,  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
6
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AGILENT 35670A  
Supplemental Operator’s Guide  
Input  
CH1 Rng: 501.7819 mVpk  
CH3 Rng: 2.5149 Vpk  
CH2 Rng: 631.706 mVpk  
CH4 Rng: 2.5149 Vpk  
Date: 10-02-96 Time: 08:42:00 PM  
A: CH1 Pwr Spec  
X:160 Hz  
Y:169.558 mVrms  
1
Vrms  
LogMag  
6
decades  
1
uVrms  
0Hz  
800Hz  
Quantifying Power Spectrum Results  
Use the marker knob to read the amplitude at any measured frequency. Rotate the  
knob on the AGILENT 35670A front panel until the marker indicator (the small  
diamond following the spectral trace) is placed at the frequency of interest. The  
frequency and amplitude at this bin is presented as X and Y values at the top of the  
trace. Units of [Hz] and [Vrms] or [grms] identify the results.  
Special marker features such as peak tracking can speed analysis. To always track  
the peak amplitude and frequency, follow these steps:  
Press the [Marker] hardkey.  
Press [PEAK TRK ON OFF] softkey (F6) until ON is highlighted.  
The frequency and amplitude of the peak bin in every trace will be determined and  
displayed.  
7
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 5 : Improving Measurement Results  
Frequency Zooming to Increase Resolution  
The AGILENT 35670A has the ability to zoom in on a signal to show detail with  
very fine resolution. After choosing a center frequency, it is possible to decrease the  
span and therefore increase the resolution all the way down to 61 µHz. To zoom in  
on a signal, move the marker to the desired center frequency, then:  
Press the [Freq] hardkey.  
Press the [CENTER] softkey (F2).  
Press the [Mkr Value] hardkey.  
To set a new, lower span,  
Press the [Freq] hardkey.  
Press the [Down Arrow] hardkey  
Press the yellow [Start] hardkey to begin the zoomed measurement.  
To return to baseband measurements,  
Press the [Freq] hardkey.  
Press the [ZERO START] softkey (F5).  
Maximizing Dynamic Range  
The default setting for input range is CH1 AUTO RANGE. For steady-state signals  
this works well because the front end will find the input range that just exceeds the  
signal level, and therefore maximize the dynamic range of the measurement. When a  
front end is set up to autorange and the signal either overloads or becomes too faint  
for the current range setting, the analyzer automatically searches for a new range and  
then re-starts the measurement. To select CH1 AUTO RANGE:  
Select the [CH1 AUTO RANGE] softkey (F6)  
If a signal is not steady, but has periods of high and low levels, then CH1 AUTO  
RANGE may not set the front end at the most useful range. Instead, try CH1 AUTO  
UP ONLY. This causes the input range to ratchet up when an overload is detected,  
however when the signal is quiet, the front end range is not reduced. This prevents  
an overload if another high level signal is expected. CH1 AUTO UP ONLY works  
well with transient signals such as those expected during impact testing. To set up  
this condition:  
Press the [Input] hardkey.  
Select the [CH1 AUTO UP ONLY] softkey (F5).  
8
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AGILENT 35670A  
Supplemental Operator’s Guide  
If continuous real-time measurements over a long duration are required, and  
absolutely no overload conditions are desired, then a fixed input range can be set that  
is greater than any signal expected. During periods of low signal level, dynamic  
range will not be optimal, however the entire measurement can be completed without  
overloads. To set up a fixed range of 1 volt:  
Press the [Input] hardkey.  
Select the [CHANNEL 1 RANGE] softkey (F3), enter 1, then press the  
[Vpk] softkey (F1).  
If engineering units are turned on ([XDCR UNIT ON OFF]) then the range can be  
specified in EU. For example, if an accelerometer is connected to channel 1 with  
XDCR UNIT turned on and XDCR UNIT LABEL specified as [g], then the input  
range can be specified as 4 “g” as per the following:  
Press the [Input] hardkey.  
Select the [CHANNEL 1 RANGE] softkey (F3)  
Enter 4, then press the [EU] softkey (F8).  
Averaging to Reduce Measurement Variance  
Spectral measurements of steady signals give results which have a statistical  
variation over time. Averaging several results will help reduce this variation. The  
AGILENT 35670A has several averaging techniques available. For general  
spectrum measurements, RMS or power averaging is commonly used. To average a  
series of ten spectrum measurements using RMS averaging, follow these steps:  
Press the [Avg] hardkey.  
Press the [NUMBER AVERAGES] softkey (F2), enter 10, then press the  
[ENTER] softkey (F1).  
Press the [AVERAGE TYPE] softkey (F3)  
Press the [RMS] softkey (F1)  
Press the [Avg] hardkey.  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
9
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AGILENT 35670A  
Supplemental Operator’s Guide  
Systm Util  
Date: 10-02-96  
Time: 08:40 PM  
Date: 01-02-04 Time: 12:44:00 PM  
A: CH1 Pwr Spec  
X:160 Hz  
Y:174.015 mVrms  
1
Vrms  
LogMag  
6
decades  
1
uVrms  
0Hz  
AVG:  
5
800Hz  
10  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 6 : Measuring a Single Channel Time Waveform  
This section contains procedures for setting up and measuring a single channel time  
waveform using an AGILENT 35670A Dynamic Signal Analyzer. Included are  
steps to select single channel operation, set up the trace time length, and set up  
triggering to capture a transient event. Instructions will also be presented to scale the  
time trace.  
Selecting Single Channel Operation  
To measure a single-channel time waveform, turn on the AGILENT 35670A and  
then:  
Press the [Inst Mode] hardkey  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Note: if the AGILENT 35670A was already turned on and in an unknown  
state, then preset the analyzer by doing the following:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Then set the instrument mode to single channel as above.  
Time Record Length in Seconds vs. Resolution  
Span - Hz  
100 lines  
200 lines  
400 lines  
800 lines 1600 lines  
51200 Hz 0.001953 s 0.003906 s 0.007813 s 0.015625 s 0.03125 s  
25600 Hz 0.003906 s 0.007813 s 0.015625 s  
0.03125 s  
0.0625 s  
0.125 s  
0.25 s  
0.5 s  
0.0625 s  
0.125 s  
0.25 s  
0.5 s  
1 s  
12800 Hz 0.007813 s 0.015625 s  
0.03125 s  
0.0625 s  
0.125 s  
0.25 s  
0.5 s  
6400 Hz 0.015625 s  
0.03125 s  
0.0625 s  
0.125 s  
0.25 s  
0.5 s  
1 s  
3200 Hz  
1600 Hz  
800 Hz  
0.03125 s  
0.0625 s  
0.125 s  
0.25 s  
0.5 s  
1 s  
1 s  
2 s  
4 s  
8 s  
2 s  
4 s  
8 s  
16 s  
400 Hz  
1 s  
200 Hz  
2 s  
100 Hz  
2 s  
4 s  
50 Hz  
2 s  
4 s  
8 s  
16 s  
32 s  
25 Hz  
4 s  
8 s  
16 s  
32 s  
64 s  
12.5 Hz  
6.25 Hz  
8 s  
16 s  
32 s  
64 s  
128 s  
256 s  
512 s  
16 s  
32 s  
64 s  
32 s  
64 s  
64 s  
128 s  
256 s  
512 s  
1024 s  
2048 s  
4096 s  
8192 s  
128 s  
256 s  
512 s  
1024 s  
2048 s  
4096 s  
3.125 Hz  
1.5625 Hz  
0.78125 Hz  
0.390625 Hz  
0.1953125 Hz  
128 s  
256 s  
512 s  
1024 s  
2048 s  
128 s  
256 s  
512 s  
1024 s  
11  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Selecting Time Record Length  
The default time record length at a frequency span of 51.2 kHz is only 7.8 ms, which  
is usually not enough time to capture a mechanical event or observe a transducer’s  
time domain signal. To increase the time record length to 0.25 s, perform the  
following steps:  
Press the [Freq] hardkey  
Press the [RECORD LENGTH] softkey (F8)  
Enter 0.25 and then press the [S] softkey (F1)  
The analyzer selects a new frequency span of 1.6 kHz, which at the default  
resolution of 400 lines, takes 0.25 seconds to capture. The following table outlines  
the time record lengths for all possible frequency spans and resolutions:  
Displaying Time Waveforms  
Time waveforms are displayed in a time trace. To set up the analyzer to display a  
single time trace of channel 1, follow these steps:  
Press the [Disp Format] hardkey.  
Press the [SINGLE] softkey (F1)  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [TIME CHANNEL 1] softkey (F5)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Using Manual Arm to Capture a Single Time Waveform  
Often it is desirable to observe just one time waveform in detail. To acquire just one  
record length at a time, follow these instructions:  
Press the [Trigger] hardkey.  
Select the [ARM SETUP] softkey (F7)  
Select the [MANUAL ARM] softkey (F2)  
Press the yellow [Start] hardkey to begin the measurement.  
Press the [Trigger] hardkey again.  
Then to arm a single time record,  
Press the [ARM] softkey (F9)  
One time record will be captured and displayed. To capture another time record,  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [ARM] softkey (F9) again.  
Event Triggering  
The AGILENT 35670A has the ability to trigger the acquisition of a time waveform  
based on the slope and level of the measured signal. To set up triggering properly,  
the polarity of the measured pulse must be known in advance: will the event start  
with a negative slope or positive slope? Will the event be mostly positive or mostly  
negative? Use trial measurements to determine polarity if unknown.  
Proper triggering is also affected by the input range. Fortunately the AGILENT  
35670A has the ability to set the trigger point to be a percentage of the input range,  
so even with CH1 AUTO UP ONLY, successful triggering should be possible  
automatically.  
To specify trigger parameters for a “positive” event on channel 1 where the trigger  
point should have a positive slope, follow these steps:  
Press the [Trigger] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F3) until 1 is highlighted.  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [CHANNEL LEVEL] softkey (F1)  
Enter 5 then press the [PERCENT (%)] softkey (F4)  
Press the [SLOPE POS NEG] softkey (F5) until POS is highlighted.  
Use pre-triggering to acquire some data before the trigger point. To set up a 0.01s  
pre-trigger condition, follow these steps:  
Press the [Trigger] hardkey.  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [ALL CHANNELS] softkey (F8)  
Press the [CHANNEL * DELAY] softkey (F9)  
Enter -.01 then press the [S] softkey (F1)  
To start the data acquisition,  
Press the yellow [Start] hardkey.  
The analyzer should show in highlighted text above the trace:  
WAITING FOR CH 1 TRIGGER  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Input  
CH1 Rng: 1.0012 Vpk  
CH3 Rng: 2.5149 Vpk  
CH2 Rng: 631.706 mVpk  
CH4 Rng: 2.5149 Vpk  
Date: 10-02-96 Time: 08:47:00 PM  
A: CH1 Time  
2.5  
X:38.0859 ms  
Y:1.06837 V  
V
Real  
500  
mV  
/div  
-2.5  
V
-9.7656ms  
489.7461ms  
Quantifying Time Trace Results  
Use the marker knob to read the amplitude at any time during the trace. Rotate the  
knob on the AGILENT 35670A front panel until the marker indicator (the small  
diamond following the spectral trace) is placed at the desired time. The time and  
amplitude at this bin is presented as X and Y values at the top of the trace. Units of  
[s] and [Vrms] or [grms] identify the results.  
Peak tracking is very useful for determining maximum amplitude of positive peaks  
in the time domain:  
Press the [Marker] hardkey.  
Press [PEAK TRK ON OFF] softkey (F6) until ON is highlighted.  
Care must be taken with negative peaks, however, because PEAK TRK ON only  
looks for the maximum value, and large negative peaks will be ignored.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 7 : Measuring Dual Channel Spectra  
This section contains procedures for setting up and measuring a dual channel  
spectrum using an AGILENT 35670A Dynamic Signal Analyzer. Procedures are  
similar to those in the section “Measuring Single Channel Spectrum,” however  
display setup and results are different and will be described here.  
To set up the analyzer for a dual channel spectrum measurement, proceed as follows:  
Presetting the Analyzer  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Pause/Cont] hardkey if desired.  
Selecting Dual Channel Operation  
Measure two signals with the default two-channel instrument mode. If the analyzer  
has been changed to 1 or 4 channel operation, then follow these steps:  
Press the [Inst Mode] hardkey  
Press [CHANNELS 1 2 4 ] softkey (F7) until 2 is highlighted.  
Selecting Frequency Span  
Reduce the span to 800 Hz as follows:  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2)  
Displaying Dual-Channel Power Spectrum Measurements  
To see the results of a dual-channel measurement, the analyzer’s display format must  
be changed to display two traces. Proceed as follows:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3)  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [PWR SPEC CHANNEL 1] softkey (F3)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the [Active Trace] hardkey again.  
Press the [B] softkey (F2).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Note: many of these keystrokes are not necessary if performed in the given order  
because the analyzer defaults to many of these settings.  
To acquire dual channel spectra,  
Press the yellow [Start] hardkey.  
Meas Data  
[FFT]  
A: CH1 Pwr Spec  
C: CH1 Time  
B: CH2 Pwr Spec  
D: CH2 Time  
Date: 10-02-96 Time: 08:49:00 PM  
A: CH1 Pwr Spec  
X:60  
Hz  
Y:147.382 mVrms  
1
Vrms  
LogMag  
6
decades  
1
uVrms  
0Hz  
800Hz  
B: CH2 Pwr Spec  
X:60  
Hz  
Y:80.4887 mVrms  
1
Vrms  
LogMag  
4
decades  
100  
uVrms  
0Hz  
800Hz  
Using Markers with Dual Channel Measurements  
Each trace has independent marker control. All functions available for a single  
marker are possible with both markers. To set up individual, independent markers  
on each channel, follow these steps:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Marker] hardkey.  
Toggle the [MARKER ON OFF] softkey (F1) until ON is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Use the marker knob to read the amplitude at any measured frequency for Channel 1  
in Trace A.  
To set up the marker for Channel 2 in Trace B,  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F2).  
Press the [Marker] hardkey.  
Toggle the [MARKER ON OFF] softkey (F1) until ON is highlighted.  
The marker knob is now active for Trace B, which is Channel 2. To gain control of  
the marker on Trace A again, make it the active trace as follows:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Coupled Markers  
Markers on multiple traces can be coupled so that one marker will always track the  
frequency specified in another trace. This makes comparisons of level differences  
across channels simple. To set up coupled markers so that Trace B will follow the  
marker frequency specified in Trace A, do the following:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Marker] hardkey.  
Toggle the [COUPLED ON OFF] softkey (F1) until ON is highlighted.  
Move the knob to move the marker in Trace A. Notice that the marker in Trace B  
moves to the same frequency.  
Coupled Markers with Peak Tracking  
Coupled markers can be further used to track a peak frequency in Trace A and  
determine the response amplitude at the peak frequency in Trace B. To do this, leave  
coupled markers on, as above, then set up peak tracking in Trace A as follows:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Marker] hardkey.  
Toggle the [PEAK TRK ON OFF] softkey (F1) until ON is highlighted.  
Press the yellow [Start] hardkey.  
Notice that the marker in Trace A moves to the peak value, whereas the marker in  
Trace B moves to the same frequency as determined in Trace A.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 8 : Improving Dual Channel Measurement Results  
Maximizing Dynamic Range  
Autoranging to maximize the dynamic range of measurements in the AGILENT  
35670A can function on all channels simultaneously. Therefore all capability  
previously mentioned for single-channel front-end ranging is available for dual-  
channel operation.  
To set up autorange on all channels, follow these steps:  
Press the [Input] hardkey.  
Press [ALL CHANNELS] softkey (F2).  
Select the [CH* AUTO RANGE] softkey (F6)  
For signals that are not steady, use CH* AUTO UP ONLY. CH1 AUTO UP ONLY  
can be used for all channels to set up modal impact testing. To set up this condition:  
Press the [Input] hardkey.  
Select the [CH* AUTO UP ONLY] softkey (F5).  
To set up the same fixed range on all channels:  
Press the [Input] hardkey.  
Select the [CHANNEL * RANGE] softkey (F3)  
Enter the range, either in units of g or Volts.  
Dual Channel Averaging  
Averaging to reduce measurement variance applies to all channels being measured.  
Dual channel averaging is set up the same as single channel averaging:  
Press the [Avg] hardkey.  
Press the [NUMBER AVERAGES] softkey (F2), enter 10, then press the  
[ENTER] softkey (F1).  
Press the [AVERAGE TYPE] softkey (F3)  
Press the [RMS] softkey (F1)  
Press the [Avg] hardkey.  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Avg  
[FFT]  
Type: RMS  
Update Rt: 5  
Number: 10  
Overlap: 0 %  
Date: 10-02-96 Time: 08:51:00 PM  
A: CH1 Pwr Spec  
X:60  
Hz  
Y:112.185 mVrms  
1
Vrms  
LogMag  
5
decades  
10  
uVrms  
0Hz  
AVG: 10  
800Hz  
B: CH2 Pwr Spec  
100  
X:60  
Hz  
Y:95.0385 mVrms  
mVrms  
LogMag  
4
decades  
10  
uVrms  
0Hz  
AVG: 10  
800Hz  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 9 : Measuring Dual Channel Time Waveforms  
This section contains procedures for setting up and measuring a single channel time  
waveform using an AGILENT 35670A Dynamic Signal Analyzer. Included are  
steps to select single channel operation, set up the trace time length, and set up  
triggering to capture a transient event. Instructions will also be presented to scale the  
time trace.  
Selecting Dual Channel Operation  
To measure a single-channel spectrum, turn on the AGILENT 35670A. The default  
instrument mode is dual-channel operation.  
Note: if the AGILENT 35670A was already turned on and in an unknown  
state, then preset the analyzer by doing the following:  
Press the green [Preset] hardkey.  
Press [DO PRESET] softkey (F1).  
This always returns the analyzer to dual-channel operation.  
Selecting Time Record Length  
Time record length can be entered directly or indirectly. It is entered directly under  
the [Freq] hardkey as follows (this example sets up a 0.25 second time record):  
Press the [Freq] hardkey  
Press the [RECORD LENGTH] softkey (F8)  
Enter 0.25 and then press the [S] softkey (F1)  
Time record length can also be specified indirectly by entering frequency and  
resolution in lines. The relationship between time record length (T), lines of  
resolution (N), and frequency (F) is:  
N
T =  
(
)
1.024F  
For 400 lines of resolution (default) and 1600 Hz span, the time record length should  
be 400/(1.024*1600) 0.25 seconds. The table showing the relationship between  
lines, span, and time record length can be found in the section on Single Channel  
Time Waveforms.  
Displaying Dual Time Waveforms  
Dual time waveforms can be shown in the UPPER/LOWER display format, with  
AUTO SCALE turned ON, as follows:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1)  
Press the [Meas Data] hardkey.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [TIME CHANNEL 1] softkey (F5)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted..  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [TIME CHANNEL 2] softkey (F5)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Arming Dual Channel Time Measurements  
To manually arm a dual channel time measurement, proceed the same as for the  
single channel case:  
Press the [Trigger] hardkey.  
Select the [ARM SETUP] softkey (F7)  
Select the [MANUAL ARM] softkey (F2)  
Press the yellow [Start] hardkey to begin the measurement.  
Press the [Trigger] hardkey.  
Then to arm a single time record,  
Press the [ARM] softkey (F9)  
One time record will be captured and displayed. To capture another time record,  
Press the [ARM] softkey (F9) again.  
Triggering a Dual-Channel Time Measurement  
Either channel may be monitored to initiate a trigger for a measurement. Setting up  
the trigger event is the same as for single channel time waveforms, except that  
channel 1 or channel 2 must be selected as the trigger. To specify the trigger  
channel, proceed as follows:  
Press the [Trigger] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F3) until 1 is highlighted.  
This sets up the analyzer to trigger off an event on channel 1. To set up channel 2 as  
the trigger channel, do the following:  
Press the [Trigger] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F3) until 2 is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Then set up trigger parameters (for a positive event, positive slope) as follows:  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [CHANNEL LEVEL] softkey (F1)  
Enter 5 then press the [PERCENT (%)] softkey (F4)  
Press the [SLOPE POS NEG] softkey (F5) until POS is highlighted.  
Trigger Delay  
Both channels should acquire data using the same pre-trigger delay. To set up a  
0.01s pre-trigger condition, follow these steps:  
Press the [Trigger] hardkey.  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [ALL CHANNELS] softkey (F8)  
Press the [CHANNEL * DELAY] softkey (F9)  
Enter -.01 then press the [S] softkey (F1)  
To start the data acquisition,  
Press the yellow [Start] hardkey.  
The analyzer should show in highlighted text above the trace:  
WAITING FOR CH 1 TRIGGER  
Trigger  
[FFT]  
Arm: Automatic  
Chn Level: 5 %  
Waterfall Steps: 15  
Slope: Positive  
Date: 10-03-96 Time: 05:23:00 PM  
A: CH1 Time  
X:472.168 ms  
Y:371.577 mV  
500  
mV  
Real  
100  
mV  
/div  
-500  
mV  
-9.7656ms  
X:472.168 ms  
489.7461ms  
Y:-241.753 mV  
B: CH2 Time  
500  
mV  
Real  
100  
mV  
/div  
-500  
mV  
-9.7656ms  
489.7461ms  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Using Markers with Dual Channel Time Measurements  
Compare the time trace of Channel 1 with Channel 2 using two techniques: peak  
tracking and coupled markers. With peak tracking active on both channels, it is  
possible to measure an event with two channels and easily compare peak amplitudes.  
Set set up peak tracking for both channels, do the following:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Marker] hardkey.  
Toggle the [PEAK TRK ON OFF] softkey (F6) until ON is highlighted.  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F2).  
Press the [Marker] hardkey.  
Toggle the [PEAK TRK ON OFF] softkey (F6) until ON is highlighted.  
Coupled markers can provide a quick comparison of relative levels during a transient  
event at a specific time. To set up peak tracking on Channel 1 and force the marker  
on Channel 2 to the time of Channel 1 peak, do the follow:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Marker] hardkey.  
Toggle the [PEAK TRK ON OFF] softkey (F6) until ON is highlighted.  
Toggle the [COUPLED ON OFF] softkey (F1) until ON is highlighted.  
Peak tracking looks for the maximum positive level in a trace. Therefore do not use  
peak tracking to determine the maximum absolute amplitude of negative pulses in a  
time trace.  
Section 10 : Measuring Dual Channel Spectra and Time Waveforms  
Two signals can be measured and examined in the time and frequency domains  
simultaneously. To accomplish this, a quad display format must be set up as  
follows:  
First, preset the analyzer:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
This places the analyzer into the default two channel mode. Set up the transducer  
parameters as described previously, if desired. Then, set up the display for four  
traces:  
Press the [Disp Format] hardkey.  
Press the [QUAD] softkey (F6).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Active Trace] hardkey.  
Press the [A B C D] softkey (F7).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted..  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
The default QUAD display shows Channel 1 power spectrum in Trace A, Channel 2  
power spectrum in Trace B, Channel 1 time in Trace C, and Channel 2 time in Trace  
D.  
Individual markers can be used on each trace, or peak tracking and coupled markers  
can be used as described for dual traces.  
If averaging is applied to the power spectrum measurements, then the QUAD display  
will show the averaged power spectra in Trace A and B, and the previously acquired  
time traces in Trace C and D.  
Scale  
Trace: A  
Per Div: 5  
Ref Lvl: 1  
Ref Pos: Top  
Date: 10-02-96 Time: 08:54:00 PM  
A: CH1 Pwr Spec  
X:60  
Hz  
Y:172.071 mVrms  
1
Vrms  
LogMag  
10  
uVrms  
0Hz  
AVG: 10  
AVG: 10  
800Hz  
800Hz  
B: CH2 Pwr Spec  
X:60  
Hz  
Y:88.5405 mVrms  
Y:427.266 mV  
100  
mVrms  
LogMag  
10  
uVrms  
0Hz  
C: CH1 Time  
500  
X:14.6484 ms  
X:14.6484 ms  
mV  
Real  
-500  
mV  
0s  
499.5117ms  
Y:279.515 mV  
D: CH2 Time  
500  
mV  
Real  
-500  
mV  
0s  
499.5117ms  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 11 : Modal Testing Using a Hammer and Accelerometer  
Hammer testing is often the easiest and quickest technique for measuring frequency  
response functions used in modal analysis. Instructions for using a hammer with a  
force transducer and an accelerometer to measure frequency response functions are  
presented.  
Setting Up the Transducer Parameters  
Connect the force transducer on the hammer to Channel 1. Mount the response  
accelerometer to the desired location on the structure, and connect it (or its  
preamplifier) to Channel 2. Preset the analyzer and set up transducer parameters as  
follows, assuming an ICP accelerometer with a sensitivity of 11 mV/g and an ICP  
force transducer on the hammer with a sensitivity of 5 mV/lb:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Wait for the analyzer to finish its preset routine.  
Press the [Pause/Cont] hardkey to pause the current measurement.  
Set up the force transducer parameters as follows:  
Press the [Input] hardkey  
Press [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press [FRONT END CH1 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press the [Input] hardkey.  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 5, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Press the [MORE CHOICES] softkey (F9).  
Select the [ lb ] softkey (F6).  
[XDCR UNIT CH1 SETUP] softkey (F8)  
Set up the accelerometer parameters as follows:  
Press the [Input] hardkey.  
Press [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press [FRONT END CH2 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press the [Input] hardkey.  
Press [XDCR UNIT CH2 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 11, then press the [mV/EU] softkey (F2).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Select the [g] softkey (F2).  
Setting Up Input Range  
Use CH* AUTO UP ONLY as the autorange routine as follows:  
Press the [Input] hardkey.  
Press [ALL CHANNELS] softkey (F2).  
Select the [CH* AUTO UP ONLY] softkey (F5).  
Then tap the structure with the hammer once. A yellow overload light by the input  
BNC connectors will indicate an overload, and the range will increase one step.  
Continue tapping on the structure, one tap at a time, allowing time for the input range  
to increase, until an overload is no longer indicated. This may take many hammer  
strikes. When an overload on either channel is no longer indicated, then the ranges  
are set correctly.  
Choosing a Preliminary Frequency Span  
Setting up a frequency response measurement is an interative process. A span is  
selected, a measurement is made, and the results are examined to determine if a  
narrower or wider span is required. To start measuring frequency response, you  
must select an initial span:  
Press the [Freq] hardkey.  
Enter 1600 and then press the [Hz] softkey (F2).  
Note: span should be any frequency that encompasses all modes of interest. If in  
doubt, start with a wider span.  
Specifying Trigger Parameters  
Hammer testing is triggered by the signal from the hammer. Without a force  
transducer, the trigger must come from the accelerometer that is attached to the  
hammer and connected to Channel 1. To set up a Channel 1 trigger, follow these  
steps:  
Press the [Trigger] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F3) until 1 is highlighted.  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [CHANNEL LEVEL] softkey (F1)  
Enter 5 then press the [PERCENT (%)] softkey (F4)  
Press the [SLOPE POS NEG] softkey (F5) until POS is highlighted.  
Press the [Trigger] hardkey.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [ALL CHANNELS] softkey (F8)  
Press the [CHANNEL * DELAY] softkey (F9)  
Enter -.01 then press the [S] softkey (F1)  
Now to check that the trigger parameters are correct,  
Press the yellow [Start] hardkey.  
The analyzer should show in highlighted text above the trace:  
WAITING FOR CH 1 TRIGGER  
Tap the hammer on the test structure to see if the measurement will trigger. If it will  
not, adjust the trigger level and slope until successful.  
Setting Up Time Displays  
View both the time trace and the windowed time trace for both channels using the  
QUAD display format as follows:  
Press the [Disp Format] hardkey.  
Press the [QUAD] softkey (F6).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [TIME CHANNEL 1] softkey (F5)  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F1)  
Press the [TIME CHANNEL 2] softkey (F5)  
Press the [Active Trace] hardkey.  
Press the [C] softkey (F1)  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [MORE CHOICES] softkey (F9)  
Press the [WINDOWED TIME CH 1] softkey (F5)  
Press the [Active Trace] hardkey.  
Press the [D] softkey (F1)  
Press the [WINDOWED TIME CH 2] softkey (F5)  
Press the [Active Trace] hardkey.  
Press the [A B C D] softkey (F7).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
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Supplemental Operator’s Guide  
Window  
[FFT]  
Type: Force/Expo  
Width: 15 ms  
Decay: 30 ms  
Date: 10-02-96 Time: 09:02:00 PM  
A: CH1 Time  
X:488.281 us  
X:488.281 us  
X:488.281 us  
X:488.281 us  
Y:67.1154 mV  
80  
mV  
Real  
-20  
mV  
-9.766ms  
115.112ms  
115.112ms  
115.112ms  
115.112ms  
B: CH2 Time  
300  
Y:-74.925 mV  
Y:48.1237 mV  
Y:-53.234 mV  
mV  
Real  
-200  
mV  
-9.766ms  
C: CH1 Win Time  
70  
mV  
Real  
-30  
mV  
-9.766ms  
D: CH2 Win Time  
250  
mV  
Real  
-250  
mV  
-9.766ms  
Using Force/Response Windows  
Hammer measurements for modal analysis typically require special windows, named  
Force/Response windows, to maximize measurement quality. The force window  
merely zeros out the trace after a fixed time interval, so that noise or bumps from the  
hammer after the desired impact do not get interpreted as excitation applied to the  
structure. The fixed interval must be long enough to capture the whole pulse, so that  
measurement of the impact does not get zeroed out. A typical value for the length of  
a force window is T/7, where T is the record duration in seconds. For a 1600 Hz  
span and resolution of 400 lines, the record length is 250 ms, so a “conservative”  
force window might have a duration of 36 ms. Experience may show that a much  
shorter duration may work better.  
Response windows prevent leakage by artificially decaying the response so that by  
the end of the record the signal is less than 5% of the peak. The artificial decay is  
specified by a time constant, with shorter time constants providing higher decay  
rates. A time constant that is guaranteed to decay a signal to less than 5% is T/4.  
For a span of 1600 Hz and resolution of 400 lines, this translates into a response  
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AGILENT 35670A  
Supplemental Operator’s Guide  
window time constant of 62.5 ms. To set up these Force/Response windows, follow  
these steps:  
Press the [Window] hardkey.  
Press the [FORCE EXPO] softkey (F4).  
Press the [FORCE EXPO SETUP] softkey (F6).  
Press the [FORCE WIDTH] softkey (F6).  
Enter 36 and then press the [mS] softkey (F2).  
Press the [EXPO DECAY] softkey (F7).  
Enter 62.5 and then press the [mS] softkey (F2).  
To view the effects of theForce/Response window,  
Press the yellow [Start] hardkey.  
Tap the structure with the hammer.  
Observe the time trcaes. Compare them to their windowed time records. Determine  
if the Force/Response windows met their object. Adjust windows if necessary. If it  
appears that no window would be required, then it is possible to test with a  
“UNIFORM” (meaning factor of 1) window instead of a force/response window. To  
select a UNIFORM window,  
Press the [Window] hardkey.  
Press the [UNIFORM] softkey (F3).  
Displaying Hammer Test Results  
The results of hammer testing are frequency response functions, and the indicator of  
measurement quality is coherence. These traces can be set up as follows:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [FREQ RESP 2 / 1] softkey (F6)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted..  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [COHERENCE 2 / 1] softkey (F7)  
Averaging  
Averaging is a very effective technique for improving the quality of frequency  
response measurements. A minimum of four averages reduces noise and variance  
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AGILENT 35670A  
Supplemental Operator’s Guide  
significantly. Ten averages may take longer, but may be necessary when testing  
difficult, non-linear structures. To set up five averages, follow these steps:  
Press the [Avg] hardkey.  
Toggle the [AVERAGE ON OFF] softkey (F1) until ON is highlighted.  
Press the [NUMBER AVERAGES] softkey (F2).  
Enter 5 and press the [ENTER] softkey (F1).  
To avoid averaging overloaded data, turn on overload reject as follows:  
Press the [Avg] hardkey.  
Toggle the [OVLD REJ ON OFF] softkey (F1) until ON is highlighted.  
To start taking measurements,  
Press the yellow [Start] hardkey.  
Hammer the structure at one measurement point. After the data is acquired and  
displayed, hammer the structure again, and repeat 5 times until the average is  
complete.  
Avg  
[FFT]  
Type: RMS  
Update Rt: 5  
Number: 5  
Overlap: 0 %  
Date: 10-02-96 Time: 09:06:00 PM  
A: Freq Resp2/1  
100  
X:2.96 kHz  
Y:98.678  
LogMag  
4
decades  
10  
e-3  
0Hz  
B: Coherence2/1  
1
AVG:  
5
3.2kHz  
X:2.96 kHz  
Y:963.738 e-3  
Real  
100  
e-3  
/div  
0
0Hz  
AVG:  
5
3.2kHz  
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Supplemental Operator’s Guide  
Changing Frequency Span  
Changing frequency span or resolution affects three important parameters in hammer  
testing which must be changed to correspond to the new time record length: Trigger  
Delay, Force Window Width, and Response Window Decay Time. The following  
relationship between the parameters can be used as a guideline:  
N
T =  
(
)
1.024F  
Where T is the time record length in seconds, N is the resolution in lines, and F is the  
frequency span in Hz.  
Delay = 0.1(T)  
T
ForceWidth =  
7
T
ExponentialDecay =  
4
When the frequency span is halved, the Time Record length doubles, as does the  
Delay time, Force Width, and Exponential Decay. All three parameters should  
change with the inverse of the change in frequency span.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 12 : Hammer Test Setup Without a Force Transducer  
Hammer testing for modal analysis without a force transducer can yield usable  
results if an accelerometer is placed on the hammer and used to trigger the  
measurement. Although frequency response functions acquired with this technique  
will be affected by the dynamic characteristics of the hammer assembly and also its  
mass-loading effects, approximate mode frequencies and mode shapes can still be  
computed using modal analysis software.  
On the other hand, power spectra obtained by measuring the single-channel response  
to a non-instrumented hammer strike may also provide information regarding modal  
frequencies and shapes, but success is too dependent on the consistency of the  
hammer strike, and therefore this technique is not recommended.  
Setting Up the Hammer Test Without a Force Transducer  
Attach an accelerometer to the hammer using cement or wax, and connect this  
transducer to Channel 1. Attach the response accelerometer to the desired location  
on the structure, and connect it to Channel 2. Preset the analyzer and set up  
transducer parameters as described in the section “Measuring with Transducers.”  
Then proceed with the test in accordance with the proceeding section on “Modal  
Testing with a Hammer and Accelerometer.”  
Avg  
[FFT]  
Type: RMS  
Update Rt: 5  
Number: 5  
Overlap: 0 %  
Date: 10-02-96 Time: 09:24:00 PM  
A: Freq Resp2/1  
X:656 Hz  
Y:444.409  
1
e+3  
LogMag  
5
decades  
10  
e-3  
0Hz  
B: Coherence2/1  
1
AVG:  
5
3.2kHz  
X:656 Hz  
Y:939.573 e-3  
Real  
100  
e-3  
/div  
0
0Hz  
AVG:  
5
3.2kHz  
32  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 13 : Order Domain Results in List Mode  
Machinery run-ups and run-downs can be analyzed with order analysis, which is  
spectral analysis normalized to RPM. Results can be simplified by examining only a  
list of amplitude versus order, so that only desired results are examined.  
To set up and measure a list of 10 orders for a machinery run-up, follow these steps:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Pause/Cont] hardkey if desired.  
Press the [ORDER ANALYSIS] softkey (F3).  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Press the [Input] hardkey  
Press the [CH1 AUTO UP ONLY] software (F5).  
Order analysis requires a tachometer signal connected to the TACH BNC at  
the back of the analyzer. To set up the AGILENT 35670A for the tachometer  
signal, follow these steps:  
Press the [TACHOMETR SETUP] softkey (F9).  
Toggle the [TACH DISP ON OFF] softkey (F6) until ON is highlighted.  
Press the [TACH PULS PER REV] softkey (F1).  
Enter the number of tachometer pulses per shaft revolution  
and press the [ENTER] softkey (F1).  
Press the [LEVEL] softkey (F3).  
Enter the tachometer level and press the [ENTER] softkey (F1).  
If in doubt about the tachometer level, enter 0.5 V and experiment with  
level, slope, and trigger range until a tachometer display is shown.  
Prepare the order display as follows:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3).  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F1)  
Prepare the order results list as follows:  
Press the [Analys] hardkey.  
Press the [DATA TABLE] softkey (F5).  
Toggle the [TABLE ON OFF] softkey (F1) until ON is highlighted.  
Press the [INSERT X VALUE] softkey (F4).  
Enter 1 and press the [ORDERS] softkey (F1).  
Enter 2 and press the [ORDERS] softkey (F1).  
Enter 3 and press the [ORDERS] softkey (F1).  
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Supplemental Operator’s Guide  
Enter 4 and press the [ORDERS] softkey (F1).  
Enter 5 and press the [ORDERS] softkey (F1).  
Enter 6 and press the [ORDERS] softkey (F1).  
Enter 7 and press the [ORDERS] softkey (F1).  
Enter 8 and press the [ORDERS] softkey (F1).  
Enter 9 and press the [ORDERS] softkey (F1).  
Enter 10 and press the [ORDERS] softkey (F1).  
After the data table is built, it can be saved to disk with the following steps:  
Insert a 3.5” diskette into the AGILENT 35670A  
Press the [Save/Recall] hardkey.  
Press the [SAVE MORE] softkey (F3).  
Press the [SAVE DATA TABL] softkey (F4).  
Press the [ENTER] softkey (F1) to save the data table to the default  
filename “DATA1.TBL”  
“DATA1.TBL” can be recalled later to set up the structure of the data  
table.  
To start taking measurements,  
Press the yellow [Start] hardkey.  
Marker  
Trace: A  
X Ref: 0  
Y Ref: 100 u  
Date: 10-02-96 Time: 09:36:00 PM  
A: CH1 Pwr Spec  
X:2  
Order  
Y:837.946 uVrms  
Entry Label  
Order  
Vrms  
1
2
4.797  
837.946  
21.182  
96.302  
21.047  
59.76  
21.843  
154.291  
58.746  
360.559  
u
u
u
u
u
u
u
u
u
u
3
4
5
6
7
LogMag  
8
9
10  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 14 : Comparing Two-Channel Real-Time Spectra with Recalled Data  
Compare two channels of real-time data with spectra stored in registers using the  
UPPR/LOWR FRNT/BACK display format of the AGILENT 35670A. Note that the  
real-time data should be measured with the same frequency and resolution as the  
stored data if valid, direct comparisons are desired.  
Preset the analyzer as follows:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the yellow [Pause/Cont] hardkey if desired.  
Selecting Measurement Parameters  
Refer to the section entitled “Measuring Dual Channel Spectra” to set up span,  
ranges, coupling, averaging, and windowing. Transducer parameters set up is  
described in the section “Measuring with Transducers.”  
Displaying Dual-Channel Spectra Compared with Recalled Data  
The results of a dual-channel measurement are compared to recalled spectra in data  
registers via the following steps:  
Press the [Disp Format] hardkey.  
Press the [UPPR/LOWR FRNT/BACK] softkey (F5).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [PWR SPEC CHANNEL 1] softkey (F3)  
Press the [Active Trace] hardkey again.  
Press the [B] softkey (F2).  
Press the [Meas Data] hardkey.  
Press the [MORE CHOICES] softkey (F9).  
Press the [DATA REGISTER] softkey (F8).  
Press the [D1] softkey (F1).  
Press the [Active Trace] hardkey.  
Press the [C] softkey (F1).  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [PWR SPEC CHANNEL 2] softkey (F3).  
Press the [Active Trace] hardkey again.  
Press the [D] softkey (F2).  
Press the [Meas Data] hardkey.  
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Supplemental Operator’s Guide  
Press the [MORE CHOICES] softkey (F9).  
Press the [DATA REGISTER] softkey (F8).  
Press the [D2] softkey (F2).  
Recalling the Spectra from Disk  
Use data registers D1 and D2 to contain the spectra used for comparison. D1 is  
compared to Channel 1 real-time data, and D2 is compared to Channel 2 real-time  
data. Comparison data must either be measured, then stored into data registers D1  
and D2, or recalled into registers D1 and D2 from disk or non-volatile RAM. For  
instructions on how to store spectra to disk, see the section “Storing Data to a Disk  
File.” For instructions on how to store spectra to data registers, see the section  
“Storing Data in Data Registers.”  
For this section, the comparison data is assumed to be stored in the disk file  
COMPARE1.DAT” and “COMPARE2.DAT.” To recall these spectra into D1 and  
D2, respectively, follow these steps:  
Insert the 3.5” disk containing the files “COMPARE1.DAT” and  
COMPARE2.DAT.”  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D1] softkey (F1).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter COMPARE1.DAT and press the [ENTER] softkey (F1).  
Data from the file “COMPARE1.DAT” now appears in data register D1. Next, recall  
COMPARE2.DAT” into dataregister D2 as follows:  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D2] softkey (F2).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter COMPARE2.DAT and press the [ENTER] softkey (F1).  
Recalling the Spectra from Non-Volatile RAM  
The comparison data files “COMPARE1.DAT” and “COMPARE2.DAT” are stored in  
the non-volatile RAM. To recall these spectra into D1 and D2, respectively, follow  
these steps:  
Press the [Save/Recall] hardkey.  
Press the [DEFAULT DISK] softkey (F9).  
Press the [NON VOL RAM DISK] softkey (F1).  
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Supplemental Operator’s Guide  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D1] softkey (F1).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter COMPARE1.DAT and press the [ENTER] softkey (F1).  
Data from the file “COMPARE1.DAT” now appears in data register D1. Next, recall  
COMPARE2.DAT” into dataregister D2 as follows:  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D2] softkey (F2).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter COMPARE2.DAT and press the [ENTER] softkey (F1).  
The data registers now contain the comparison data. To make real-time  
measurements, start the measurement as follows:  
Press the yellow [Start] hardkey.  
Scaling the Displays  
Proper trace scaling of the FRONT/BACK displays provides a quick and clear visual  
comparison. Both traces should be set to the same scale, or at least use the same “Y  
PER DIV (DECADES).” This need to be set up for each pair of traces. After  
comparison data has been recalled into D1 and D2, and real-time measurements are  
complete on Channel 1 and Channel 2, set up scale as follows:  
Press the [Active Trace] hardkey.  
Press the [A B] softkey (F1).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the [Y PER DIV (DECADES)] softkey (F6).  
Enter 2 and press the [ENTER] softkey (F1).  
Note: Usually one, two, or three decades offers the best scale for comparison. If the  
scale is not identical, but the top reference is different, then the traces can be made  
identical. Assuming the maximum peak of both traces is about 8 mV, then the top  
reference can be set to 10 mV by the following:  
Press the [TOP REFERENCE] softkey (F2).  
Enter 0.01 and press the [ENTER] softkey (F1).  
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Supplemental Operator’s Guide  
Scaling for traces A and B are now identical. To accomplish the same trace scaling  
for C and D, follow these steps:  
Press the [Active Trace] hardkey.  
Press the [C D] softkey (F1).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the [Y PER DIV (DECADES)] softkey (F6).  
Enter 2 and press the [ENTER] softkey (F1).  
As with Traces A and B, if the top reference of C and D are not identical, set the top  
reference level as shown above.  
Using Markers to Compare  
Coupled markers can be activated for all traces, but not independently for each pair  
of traces. Use coupled markers to compare one set of traces at a time.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 15 : Waterfall Spectra at Time Intervals  
Waterfalls on the AGILENT 35670A can be used to examine and compare spectra at  
fixed intervals of time. This is especially useful when measuring non-stationary  
signals from machinery, such as during run-ups and run-downs. To see a waterfall  
display of the vibration signature, follow these steps:  
Preset the analyzer as follows:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Pause/Cont] hardkey if desired.  
Selecting Single Channel Operation  
Specify the single-channel instrument mode to measure one waterfall. Note that it is  
possible to measure and display waterfalls for two channels simultaneously. For  
single channel operation, however, the display performance will be better with only  
one channel active. To measure a single-channel waterfall, turn on the AGILENT  
35670A and then:  
Press the [Inst Mode] hardkey  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Selecting Measurement Parameters  
Refer to the section entitled “Measuring Single Channel Spectra” to set up span,  
ranges, coupling, averaging, and windowing. Transducer parameters set up is  
described in the section “Measuring with Transducers.”  
Setting Up the Waterfall Display  
The best view of a waterfall includes the current power spectrum above the waterfall  
trace. In the AGILENT35670A this is implemented with the UPPER/BIG LOWER  
display format as follows:  
Press the [Disp Format] hardkey.  
Select the [UPPER/ BIG LOWER] softkey (F4).  
Press the [Active Trace] hardkey.  
Select the [A] softkey (F2).  
Press the [Meas Data] hardkey.  
Toggle the [CHANNEL 1 2 3 4] softkey until 1 is highlighted.  
Press the [PWR SPEC CHANNEL 1] softkey (F3).  
Continuing to set up a waterfall display,  
Press the [Active Trace] hardkey.  
Select the [B] softkey (F2).  
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Supplemental Operator’s Guide  
Press the [Disp Format] hardkey.  
Press the [WATERFALL SETUP] softkey (F8).  
Toggle the [WATERFALL ON OFF] softkey (F1) until ON is highlighted.  
The default number of waterfall steps is 15, which means only 15 spectra are kept in  
memory and as new data is taken, the oldest spectra is discarded. The maximum  
number of waterfall steps which can be kept in memory depends on the RAM option  
installed in the AGILENT 35670A and the lines of resolution in each spectra. With  
standard memory and one channel active, 130 spectra can be stored with 400 lines of  
resolution. With maximum optional RAM, over 1000 spectra may be kept in  
memory.  
The z-axis range describes how many spectra will be displayed in the waterfall  
simultaneously. The default number is 15.  
Setting Up Time Step Arm  
Waterfall spectra can be acquired at constant intervals of time by arming the  
measurement using TIME STEP ARM as follows:  
Press the [Trigger] hardkey.  
Select the [ARM SETUP] softkey (F7).  
Select the [TIME STEP ARM] softkey (F4).  
Select the [TIME STEP SIZE] softkey (F8).  
Enter 1.5 and press the [S] softkey (F1).  
This sets up a 1.5 second time interval between spectra in the waterfall. Note that if  
the time record for a frequency span is too long, data cannot be acquired at the  
specified time interval. For example when the frequency span is 200 Hz and the  
resolution is 400 lines, the time record length is about 2 seconds. Waterfall spectra  
cannot be acquired any faster than a 2 second interval.  
On the other hand if the time record length is equal to or shorter than the specified  
time interval, the measurement will be armed (and triggered, when FREE RUN  
TRIGGER is selected) exactly at the time interval increment.  
To acquire a waterfall with 15 spectra at 1.5 second intervals, start the measurement:  
Press the yellow [Start] hardkey.  
Using Slice Markers with Waterfall Data  
Examine amplitude vs. time for a specified frequency using the AGILENT 35670A’s  
waterfall slice marker. Select the frequency using the waterfall marker, then display  
the time history at that frequency as follows:  
Press the [Active Trace] hardkey.  
Select the [B] softkey (F2).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
This makes the waterfall trace active.  
Press the [Marker Fctn] hardkey.  
Press the [WATERFALL MARKERS] softkey (F5).  
The SLICE SELECT softkey will be active. Use the marker knob to move the cursor  
to the frequency of interest.  
Press the [SAVE AND DISP DATA] softkey (F5).  
This one keystroke saves the selected slice into data register D2 and changes the  
Meas Data of Trace A to display data register D2. Trace A will show the amplitude  
in the selected frequency band vs. time.  
Collecting a Specified Number of Spectra During a Time Interval  
Acquire a specified number of spectra into a waterfall during a fixed interval using  
time step arm. Divide the total measurement interval by the number of spectra  
desired during the interval to determine the desired TIME STEP SIZE. For example  
to measure 10 spectra during a one minute interval, select a 6 second TIME STEP  
SIZE as follows:  
Press the [Trigger] hardkey.  
Select the [ARM SETUP] softkey (F7).  
Select the [TIME STEP ARM] softkey (F4).  
Select the [TIME STEP SIZE] softkey (F8).  
Enter 6 and press the [S] softkey (F1).  
Then specify the total number of spectra to be collected (10):  
Press the [Active Trace] hardkey.  
Select the [B] softkey (F2).  
Press the [Disp Format] hardkey.  
Select the [WATERFALL SETUP] softkey (F8).  
Select the [WATERFALL STEPS] softkey (F8).  
Enter 10 and then press the [ENTER] softkey (F1).  
When Start is pressed, a new spectra will be acquired every six seconds.  
41  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 16 : Waterfall Spectra at RPM Intervals  
Spectra can be acquired at fixed RPM intervals with RPM STEP ARM. This feature  
allows spectra to be taken at uniform RPM intervals even during erratic run-ups.  
Setting Up the Tachometer  
Connect the tachometer signal to the TACH BNC connector on the back of the  
AGILENT 35670A. Set up tachometer parameters as follows, assuming that the  
tachometer is a 1 V peak signal with 2 pulses per revolution:  
Press the [Trigger] hardkey.  
Press the [TACHOMTER SETUP] softkey (F8).  
Press the [TACH PULS PER REV] softkey (F8).  
Enter 2 then press the [ENTER] softkey (F1).  
Toggle the [TACH DISP ON OFF] softkey (F6) until ON is highlighted.  
Specifying the Start RPM  
To set up RPM interval triggering, refer to the preceding section regarding Time  
Step Arm, then follow these instructions:  
Press the [Trigger] hardkey.  
Press the [ARM SETUP] softkey (F7).  
Select the [RPM STEP ARM] softkey (F3).  
Press the [START RPM] softkey (F6).  
Press 1000 then the [RPM] softkey (F1).  
This starts the measurement when 1000 RPM.  
Press the [RPM STEP SIZE] softkey (F7).  
Press 25 then the [RPM] softkey (F1).  
This arms the measurement every 25 RPM.  
Collecting a Specified Number of Spectra During an RPM Interval  
Acquire a specified number of spectra into a waterfall during an RPM run-up using  
RPM step arm. Divide the total RPM interval by the number of spectra desired  
during the interval to determine the desired RPM STEP SIZE. For example to  
measure 15 spectra during an RPM run-up from 1000 RPM to 1750 RPM, select an  
RPM STEP SIZE of 50 as follows:  
Press the [Trigger] hardkey.  
Select the [ARM SETUP] softkey (F7).  
Select the [RPM STEP ARM] softkey (F4).  
Press the [START RPM] softkey (F6).  
Press 1000 then the [RPM] softkey (F1).  
Press the [RPM STEP SIZE] softkey (F7).  
42  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press 50 then the [RPM] softkey (F1).  
Then specify the total number of spectra to be collected (15):  
Press the [Active Trace] hardkey.  
Select the [B] softkey (F2).  
Press the [Disp Format] hardkey.  
Select the [WATERFALL SETUP] softkey (F8).  
Select the [WATERFALL STEPS] softkey (F8).  
Enter 15 and then press the [ENTER] softkey (F1).  
When Start is pressed, spectra will be acquired as soon as the tachometer reaches  
1000 RPM, and every 50 RPM thereafter until 15 spectra have been measured.  
Starting and Pausing a Measurement  
To start a waterfall measurement, press the yellow [Start] hardkey. To pause  
waterfall at any moment, press the yellow [Pause/Cont] hardkey. A measurement  
can be continued by pressing the yellow [Pause/Cont] hardkey again. The ability to  
pause a machinery run-up measurement allows the user to capture and observe  
critical data, such as a vibration resonance build-up over a certain rpm range.  
Scaling the Display  
Because a waterfall contains so much spectral information, it is often desirable to  
eliminate unwanted data from view, such as the noise floor, so that the critical data  
can be examined and compared. This is readily accomplished with display scaling.  
To scale the waterfall data acquired from Track 31 of the AGILENT Dynamic  
Signals II CD:  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F2).  
Press the [Scale] hardkey.  
Press the [TOP REFERENCE] softkey (F1).  
Press 5 then [ENTER].  
Press the [Y PER DIV (DECADES)] softkey (F6).  
Press 4 then [ENTER].  
Mechanical resonances at around 4170 RPM should become clearly visible with  
these scaling parameters.  
43  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Marker Fcn  
[Watrfall]  
Trace: B  
Base Supr: 0 %  
Save Reg: D2  
Height: 57 %  
Date: 07-24-96 Time: 11:31:00 PM  
A: D2 Pwr Spec  
1
Vrms  
LogMag  
4
decades  
100 u  
0Hz  
B: CH1 Pwr Spec  
800Hz  
Slice:122 Hz  
Trace:4.311 kRPM  
1
Vrms  
LogMag  
100  
uVrms  
4.883  
kRPM  
3.383  
kRPM  
0Hz  
800Hz  
A Properly Scaled, RPM Triggered Waterfall Display  
44  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 17 : Two-Channel Absolute and Differential Amplitude Measurement  
Measuring the relative motion between points on a machine can provide information  
regarding clearances and forces. These measurements may also demonstrate a  
susceptibility of a machine to a particular mode of vibration.  
Absolute motion can be measured as a power spectrum, with units of peak-to-peak  
displacement in mils. Relative motion is measured as the vector difference between  
two channels. It also can be displayed with units of peak-to-peak displacement in  
mils.  
When acquiring these measurements, it is very important to know the relative  
polarity of each transducer. If their polarity is opposite, then the signals must be  
added, not subtracted, to obtain differential motion.  
The best technique is to use two identical accelerometers. If the transducers are not  
the same model, then it is best to determine their relative polarity.  
Accelerometer Polarity  
To determine the polarity of two accelerometers, follow these steps:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Pause/Cont] hardkey if desired.  
Press the [Freq] hardkey  
Enter 3200 and then press the [Hz] softkey (F2).  
Press the [Input] hardkey.  
Press the [ALL CHANNELS] softkey (F2).  
Select the [CH* AUTO UP ONLY] softkey (F5).  
Set up transducer parameters as described in the section “Measuring with  
Transducers.” Then follow these steps to display a time trace of the two  
accelerometers:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [TIME CHANNEL 1] softkey (F5)  
Press the [Scale] hardkey.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted..  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F1)  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [TIME CHANNEL 2] softkey (F5)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Set up triggering on Channel 1 to 5% of range:  
Press the [Trigger] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F3) until 1 is highlighted.  
Press the [TRIGGER SETUP] softkey (F6)  
Press the [CHANNEL LEVEL] softkey (F1)  
Enter 5 then press the [PERCENT (%)] softkey (F4).  
Press the [ALL CHANNELS] softkey (F8).  
Press the [CHANNEL * DELAY] softkey (F9).  
Enter -0.01 then press the [S] softkey (F1).  
Mount the accelerometers on top of each other or very close together on a light test  
structure, then:  
Press the yellow [Start] hardkey.  
Tap the structure in the area around the two accelerometers to trigger a  
measurement.  
If the measurement overloaded, then tap again after the range has  
increased. Tap again until a trace is not overloaded.  
Press the [Marker] hardkey.  
Toggle the [COUPLED ON OFF] softkey (F2) until ON is highlighted.  
Examine the two time traces with the coupled markers to determine if the  
accelerometers are in phase or out of phase.  
Note whether the accelerometers are in phase or out of phase. The function to  
determine differential amplitude depends on this relationship.  
Measuring Amplitudes, Differential Amplitude, and Phase  
For machinery motion measurements, one display setup can show:  
displacement of Channel 1 in mils peak-to-peak  
displacement of Channel 2 in mils peak-to-peak  
46  
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AGILENT 35670A  
Supplemental Operator’s Guide  
difference in motion between Channel 1 and Channel 2 in mils peak-to-  
peak  
phase angle between the two channels.  
Set up the AGILENT 35670A  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Pause/Cont] hardkey if desired.  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2).  
Press the [Input] hardkey.  
Press the [ALL CHANNELS] softkey (F2).  
Select the [CH* AUTO UP ONLY] softkey (F5).  
Set up transducer parameters on Channel 1 and Channel 2 as per the section  
“Measuring with Transducers.” Mount the accelerometers to the machinery and  
connect them to Channel 1 and Channel 2. The following procedures assume that  
Using a Math Function to Measure Differential Motion  
For accelerometers with the same polarity  
Press the [Analys] hardkey.  
Press the [DEFINE FUNCTION] softkey (F1).  
Press the [DEFINE F1] softkey (F1).  
Press the [MEAS DATA] softkey (F1).  
Press the [LIN SPEC CHANNEL 1] softkey (F3).  
Press the [ - ] softkey (F2).  
Press the [MEAS DATA] softkey (F1).  
Toggle the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [LIN SPEC CHANNEL 2] softkey (F3).  
Press the [ENTER] softkey (F7).  
For accelerometers with opposite polarity  
Press the [Analys] hardkey.  
Press the [DEFINE FUNCTION] softkey (F1).  
Press the [DEFINE F1] softkey (F1).  
Press the [MEAS DATA] softkey (F1).  
Press the [LIN SPEC CHANNEL 1] softkey (F3).  
Press the [ + ] softkey (F1).  
Press the [MEAS DATA] softkey (F1).  
47  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Toggle the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [LIN SPEC CHANNEL 2] softkey (F3).  
Press the [ENTER] softkey (F7).  
Set up display  
Press the [Disp Format] hardkey.  
Press the [QUAD] softkey (F6).  
After a instrument preset the QUAD display format normally places PWR SPEC  
CHANNEL 1 in Trcae A and PWR SPEC CHANNEL 2 in Trace B. If this is not the  
case, then follow these steps:  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [PWR SPEC CHANNEL 1] softkey (F3)  
Press the [Active Trace] hardkey again.  
Press the [B] softkey (F2).  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press the [PWR SPEC CHANNEL 2] softkey (F3).  
Put the math function of the differential motion in Trace c:  
Press the [Active Trace] hardkey.  
Press the [C] softkey (F1).  
Press the [MORE CHOICES] softkey (F9).  
Press the [MATH FUNCTION] softkey (F7).  
Press the [F1] softkey (F1).  
Press the [Active Trace] hardkey again.  
Press the [D] softkey (F2).  
Press the [Meas Data] hardkey.  
Press the [FREQ RESP 2 / 1]] softkey (F6).  
Set up trace coordinates as peak-to-peak mil  
Press the [Active Trace] hardkey.  
Press the [A B C D] softkey (F7).  
Press the [Trace Coord] hardkey.  
Press the [Y UNITS] softkey (F8).  
Toggle the [AMPLITUDE PK PP RMS] softkey (F1) until PP is  
highlighted.  
Press the [XDCR UNIT CONVERT] softkey (F4).  
Press the [mil (DISP)] softkey (F8).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Active Trace] hardkey again.  
Press the [D] softkey (F2).  
Press the [Trace Coord] hardkey.  
Press the [PHASE] softkey (F4).  
Start measurement  
Press the yellow [Start] hardkey.  
The AGILENT 35670A will now measure motion of Channel 1 and 2 and show the  
results in Traces A and B. The difference in motion between Channel 1 and Channel  
2 is shown in Trace C. The phase angle between channels is shown in Trace D.  
Disp Frmat  
Date: 01-01-04 Time: 08:35:00 AM  
A: CH1 MOTION  
X:468 Hz  
X:468 Hz  
X:468 Hz  
X:468 Hz  
Y:39.2406 mmilpp  
Y:15.8415 mmilpp  
Y:24.6051 mmilpp  
Y:-170.713 deg  
100  
milpp  
LogMag  
10  
umilpp  
0Hz  
AVG: 10  
AVG: 10  
1.6kHz  
1.6kHz  
1.6kHz  
1.6kHz  
B: CH2 MOTION  
1
milpp  
LogMag  
10  
umilpp  
0Hz  
C: DIFFERENCE  
100  
milpp  
LogMag  
10  
umilpp  
0Hz  
D: PHASE DIFF  
180  
deg  
Phase  
-180  
deg  
0Hz  
AVG: 10  
49  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 18 : Measuring Frequency Response with the AGILENT 35670A  
Frequency response functions characterize the behavior of systems to external  
stimuli. For mechanical systems, the stimulus can be a transient force such as an  
impact from a hammer, or a broadband stimulus, such as random excitation from an  
electrodynamic shaker. The response is usually motion of the system, measured with  
and accelerometer, velocity transducer, or displacement probe.  
In either case the stimulus and the response measured with two channels of the  
AGILENT 35670A. The stimulus is usually measured on Channel 1, and the  
response is measured on Channel 2. The resulting frequency response is averaged to  
reduce noise and variance, and the result is displayed in a variety of formats that will  
be described in this section, including:  
Magnitude and phase  
Real and imaginary components (  
Nyquist Diagrams  
The quality of the frequency response measurement is determined by how much of  
the response is due to the stimulus instead of being due to noise or other undesirable,  
unmeasured forces. Quality is described by coherence, which ranges from zero to  
one, where zero means none of the response is due to the stimulus. A coherence of  
one means that the response was entirely due to the stimulus  
Measuring Frequency Response Using Impact Excitation  
Refer to the section “Modal Testing Using a Hammer and Accelerometer” to  
measure frequency response using an impact as a stimulus. An impact provides  
broadband excitation, however the impact has a high peak to RMS ratio which tends  
to reduce measurement quality.  
Measuring Frequency Response Using Broadband Excitation  
Excite a system using the AGILENT 35670A built-in source to provide broadband  
excitation with low peak to RMS ratio and the best measurement quality. Use burst-  
random noise to eliminate window distortion and reduce leakage. The following  
instructions show how to set up a modal test with these example parameters:  
electrodynamic shaker with amplifier  
ICP force transducer with sensitivity of 8 mV/lb.  
ICP accelerometer with sensitivity of 10.2 mV/G  
wire sting to connect shaker to force transducer  
burst random excitation, uniform window  
frequency span of 800 Hz, 4 averages  
results viewed as log magnitude and phase  
Set up the shaker  
Attach force transducer to structure  
50  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Attach one end of stinger to shaker and one end to force transducer  
Connect amplifier output to shaker  
Connect amplifier input to AGILENT 35670A source  
Connect the transducers  
Connect force transducer to Channel 1  
Connect accelerometer to Channel 2  
Preset the AGILENT 35670A  
Turn on the AGILENT 35670A, or  
Press the green [Preset] hardkey  
Press the yellow [Pause/Cont] hardkey if desired.  
Enter Channel 1 input parameters  
Press the [Input] hardkey  
Press [CH1 AUTO UP ONLY] softkey (F5).  
Press [FRONT END CH1 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press the [Input] hardkey  
Press [XDCR UNIT CH1 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 8, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Press the [MORE CHOICES] softkey (F9).  
Select the [ lb ] softkey (F6).  
Enter Channel 2 input parameters  
Press the [Input] hardkey  
Press [CHANNEL 1 2 3 4] softkey (F1) until 2 is highlighted.  
Press [CH2 AUTO UP ONLY] softkey (F5).  
Press [FRONT END CH2 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press the [Input] hardkey  
Press [XDCR UNIT CH2 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 10.2, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Select the [ g ] softkey (F2).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Choose measurement parameters  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2)  
Press the [Avg] hardkey.  
Press the [NUMBER AVERAGES] softkey (F2), enter 4, then press the  
[ENTER] softkey (F1).  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
Press the [Window] hardkey  
Press the [UNIFORM] softkey (F3).  
Set up display parameters  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3)  
Press the [Active Trace] hardkey.  
Press the [ AB ] softkey (F5).  
Press the [Meas Data] hardkey.  
Press the [FREQ RESP 2 / 1 ] softkey (F6)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the [Active Trace] hardkey.  
Press the [ B ] softkey (F2).  
Press the [Trace Coord] hardkey.  
Press the [PHASE] softkey (F4).  
Set up the AGILENT 35670A source (if amplifier has level control)  
Check the following connections:  
AGILENT 35670A source connected to amplifier input  
amplifier plugged in  
amplifier output connected to shaker  
force transducer connected to Channel 1  
Reduce amplifier level control the lowest setting  
Turn on amplifier  
Press the [Source] hardkey.  
Press the [RANDOM NOISE] softkey (F5)  
Press the [LEVEL] softkey (F2)  
Enter 0.5, then press the [Vpk] softkey (F1).  
Toggle the [SOURCE ON OFF] softkey (F1) until ON is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Turn up the level control on the shaker amplifier until the excitation is  
noticeable, but does not buzz or rattle. If buzzing or rattling is heard,  
then either the level is too high or the structure is loose and must be  
quieted.  
Press the [MORE CHOICES] softkey (F9)  
Press the [BURST RANDOM] softkey (F2)  
Set up the trigger  
Press the [Trigger] hardkey.  
Press the [SOURCE TRIGGER] softkey (F4).  
To acquire a burst random frequency response of the structure:  
Press the yellow [Start] hardkey.  
Avg  
[FFT]  
Type: RMS  
Update Rt: 5  
Number: 10  
Overlap: 0 %  
Date: 10-02-96 Time: 09:49:00 PM  
A: Freq Resp2/1  
1
X:0  
Hz  
Y:84.6724 e-3  
LogMag  
3
decades  
1
e-3  
0Hz  
B: Freq Resp2/1  
180  
AVG: 10  
400Hz  
X:0  
Hz  
Y:0  
deg  
deg  
Phase  
36  
deg  
/div  
-180  
deg  
0Hz  
AVG: 10  
400Hz  
Viewing Frequency Response Results with a Nyquist Diagram  
The previous display shows frequency response results with Log Magnitude and  
Phase traces. Other trace coordinates are available. To examine results in a Nyquist  
Diagram, proceed as follows:  
53  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Disp Format] hardkey.  
Press the [SINGLE] softkey (F1)  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F1).  
Press the [Trace Coord] hardkey.  
Press the [MORE CHOICES] softkey (F6).  
Press the [NYQUIST DIAGRAM] softkey (F4).  
Trac Coord  
[FFT]  
A: Nyquist  
C: Real  
B: Phase  
D: Real  
Date: 10-02-96 Time: 09:49:00 PM  
A: Freq Resp2/1  
R:-117.6 e-3  
I:-101.3 e-3  
X:262 Hz  
+j  
200  
e-3  
Imag  
Nyquist  
50  
e-3  
-1  
+1  
/div  
-300  
e-3  
-j  
AVG: 10  
-366.456e-3  
Real  
266.456e-3  
Viewing Results Using Real and Imaginary Traces  
View frequency response measurements using real and imaginary coordinates as  
follows:  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3).  
Press the [Active Trace] hardkey.  
Press the [ AB ] softkey (F5).  
Press the [Meas Data] hardkey.  
Press the [FREQ RESP 2 / 1] softkey (F6).  
Press the [Scale] hardkey.  
54  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F2).  
Press the [Trace Coord] hardkey.  
Press the [MORE CHOICES] softkey (F6).  
Press the [REAL PART] softkey (F2).  
Press the [Active Trace] hardkey.  
Press the [ B ] softkey (F2).  
Press the [IMAGINARY PART] softkey (F3).  
Assessing Measurement Quality  
Measurement quality is described by coherence, which varies from 0 to 1. To set up  
a coherence display, follow these steps:  
Press the [Meas Data] hardkey.  
Press the [COHERENCE 2 / 1] softkey (F7).  
A coherence value of 1 means the response measured by Channel 2 was due to the  
excitation of Channel 1. A coherence of 0 means that none of the response of  
Channel 2 was due to the input measured by Channel 1.  
Burst random excitation usually exhibits excellent coherence unless non-linearities  
are excited.  
55  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 19 : Two Spectral Traces Showing Mils and Ips while EU is G  
Measure an accelerometer signal and display velocity and displacement spectra with  
the UPPER/LOWER display format in the AGILENT 35670A as follows:  
Preset the AGILENT 35670A  
Turn on the AGILENT 35670A, or  
Press the green [Preset] hardkey  
Press the yellow [Pause/Cont] hardkey if desired.  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Set up transducer parameters for a 10 mV/g accelerometer:  
Press the [Input] hardkey  
Press [FRONT END CH1 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press [Input] hardkey.  
Press [XDCR UNIT CH1 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 10 (for an accelerometer with 10 mV/g sensitivity), then press the  
[mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Select the [g] softkey (F2).  
Set up display format and Trace A to measure displacement in mil (0-pk):  
Press the [Disp Format] hardkey.  
Press the [UPPER/LOWER] softkey (F3)  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F5).  
Press the [Trace Coord] hardkey.  
Press the [Y UNITS] softkey (F8)  
Toggle the [AMPLITUDE PK PP RMS] softkey (F4) until PK is  
highlighted.  
Press the [XDCR UNIT CONVERT] softkey (F4)  
Press the [mil (DISP)] softkey (F8)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the yellow [Start] hardkey.  
Set up Trace B to measure velocity in inch/s (0-pk):  
Press the [Active Trace] hardkey.  
Press the [ B ] softkey (F2).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Trace Coord] hardkey.  
Press the [Y UNITS] softkey (F8)  
Toggle the [AMPLITUDE PK PP RMS] softkey (F4) until PK is  
highlighted.  
Press the [XDCR UNIT CONVERT] softkey (F4)  
Press the [inch/s (VEL)] softkey (F6)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
57  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 20 : Peak Hold During a Machine Run-up and Coast-Down  
Peak amplitudes experienced during run-ups and coast-downs can be measured  
directly with the AGILENT 35670A using peak hold. Although the resulting spectra  
will indicate the maximum amplitude measured in each frequency bin during the  
course of the run-up and run-down, it is not possible to determine from this  
information whether the peak was due to the fundamental frequency or a harmonic.  
To measure peak amplitudes, peak hold averaging is selected with enough averages  
specified so that peaks can be accumulated during the entire run-up and run-down,  
after which the measurement is paused and the results examined.  
To set up a single-channel peak hold average for a run-up duration of 1 minute,  
proceed as follows:  
Select a frequency span and resolution, for example 800 Hz and 400  
lines.  
Determine the time record length for this combination,  
T=N/F=400/800=0.5 s  
Determine how many averages are required to last for the measurement  
duration. Navg=Duration/T=60/.5=120 averages  
Specify number of averages to be greater than this number.  
Preset the AGILENT 35670A  
Turn on the AGILENT 35670A, or  
Press the green [Preset] hardkey  
Press the yellow [Pause/Cont] hardkey if desired.  
Press [CHANNELS 1 2 4 ] softkey (F7) until 1 is highlighted.  
Specify measurement parameters  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2)  
Press the [Avg] hardkey.  
Press the [NUMBER AVERAGES] softkey (F2), enter 200, then press the  
[ENTER] softkey (F1).  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
Press the [AVERAGE TYPE] softkey (F3).  
Press the [PEAK HOLD] softkey (F5).  
Set up display format to measure peak amplitude  
Press the [Disp Format] hardkey.  
Press the [SINGLE] softkey (F1)  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F5).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
Press the yellow [Start] hardkey.  
When the run-up and run-down is completed,  
Press the yellow [Pause/Cont] hardkey and examine results.  
Avg  
[FFT]  
Type: Peak Hold  
Update Rt: 5  
Number: 100  
Overlap: 0 %  
Date: 10-02-96 Time: 09:55:00 PM  
B: CH1 Pwr Spec  
100  
X:0  
Hz  
Y:994.858 uVrms  
mVrms  
LogMag  
4
decades  
10  
uVrms  
0Hz  
AVG: 25  
400Hz  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 21 : Using an External Trigger for Time Averaging  
Use external triggering for synchronous averaging of linear spectra. With a reliable,  
consistent trigger, the resulting noise floor tends to be eliminated and the signal-to-  
noise ratio of the measurement can be optimal.  
If the trigger is TTL, with little noise and jitter, then trigger setup is accomplished as  
follows:  
Press the [Trigger] hardkey.  
Select the [EXTERNAL TRIGGER] softkey (F2).  
Press the [TRIGGER SETUP] softkey (F6)  
Toggle the [EXT LEVEL USER TTL] softkey (F1) until TTL is  
highlighted.  
Other trigger parameters such as USER EXT LEVEL and EXT RANGE do not need  
to be specified when using a TTL trigger.  
Specify User Levels for Triggering  
When the external trigger is not a TTL signal, the trigger level, slope, and range can  
be specified to accommodate a broad range of external triggers. Successful  
triggering is easiest to obtain when the external trigger signal is well characterized.  
Trigger range, level, and slope must be determined.  
Characterizing the External Trigger  
External trigger pulses can be noisy and of an unknown shape and amplitude.  
Reliable use of an external trigger requires knowledge of trigger characteristics so  
that the AGILENT 35670A can be set up properly. This section provides guidance  
in capturing and analyzing trigger signals so that reliable external triggering is  
attained.  
Connect the signal and preset the AGILENT 35670A  
Connect the external trigger signal to Channel 1.  
Turn on the AGILENT 35670A, or  
Press the green [Preset] hardkey  
Press the yellow [Pause/Cont] hardkey if desired.  
Select the Histogram/Time measurement mode. This mode turns off the anti-alias  
filter so that the actual analog signal can be examined.  
Press the [HISTOGRAM / TIME] softkey (F6).  
Press the [Meas Data] hardkey.  
Press the [UNFILTERD TIME CH 1] softkey (F6).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Acquire and Display the Trigger Signal  
Press the yellow [Start] hardkey.  
Press the [Freq] hardkey.  
Press the [UP ARROW] hardkey until only a few trigger pulses are  
visible.  
Press the yellow [Pause/Cont] hardkey to stop the measurement and  
characterize the trigger signal with the marker.  
Characterize the Trigger Signal  
Use the market knob to determine the highest and lowest level of the  
trigger pulse.  
Note if the trigger level exceeds 2V. If it does not, then the external  
trigger range can be set to 2 V and the trigger level can be set with good  
resolution. If the trigger level exceeds 2 V, then set the trigger range to  
10 V.  
Find a good trigger point on the trigger signal. Look for fast transitions or  
steep slopes, and locate the trigger point in the middle of or just before  
these areas. Note the trigger level in volts and the slope, either positive  
or negative, at the best transition point.  
Trigger range, level, and slope have now been determined.  
Setting Up External Trigger  
Set up a non-TTL trigger as follows:  
Press the [Trigger] hardkey.  
Select the [EXTERNAL TRIGGER] softkey (F2).  
Press the [TRIGGER SETUP] softkey (F6)  
Toggle the [EXT LEVEL USER TTL] softkey (F2) until USER is  
highlighted.  
Press the [USER EXT LEVEL] softkey (F3).  
Enter the trigger level in volts as determined above, and then press the  
[V] softkey (F1).  
Toggle the [EXT RANGE +/- 10 2] softkey (F4) until 2 is highlighted,  
unless the trigger exceeded 2 V, then toggle the softkey to 10 V.  
Toggle the [SLOPE POS NEG] softkey (F5) until the slope at the  
selected trigger point is highlighted.  
If the trigger appears noisy or erratic, try activating the 100 kHz external trigger  
noise filter as follows:  
Toggle the [EXT FILTER ON OFF] softkey (F6) until ON is  
highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Measuring Time Averaged Spectrums with External Triggering  
Now that the external trigger has been set up, the analyzer is ready to measure a  
signal with time averaging as follows:  
Connect the external trigger signal to the EXT TRIG port on the back of  
the AGILENT 35670A.  
Turn on the AGILENT 35670A, or  
Press the green [Preset] hardkey  
Press the yellow [Pause/Cont] hardkey if desired.  
Set up measurement parameters  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2)  
Press the [Avg] hardkey.  
Press the [AVERAGE TYPE] softkey (F3).  
Press the [TIME] softkey (F3).  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
Press the yellow [Start] hardkey.  
62  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 22 : Saving Trace Data to a 3.5” Disk or Non-Volatile RAM  
Save trace data into non-volatile RAM or 3.5” disk using the AGILENT 35670A  
Save/Recall capabilities. All AGILENT 35670A data is stored as a Standard Data  
Format (SDF) file. This data format is compatible across Agilent Technologies’s  
line of Dynamic Signal Analyzers. Utilities are available to view and plot SDF files  
from a PC and to access the data programmatically.  
Saving Trace to 3.5” Disk  
To store Trace A data as a file named “T1.DAT” on a 3.5” disk, insert a IBM-PC  
formatted disk into the AGILENT 35670A and follow these steps:  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F5).  
Press the [Save/Recall] hardkey.  
Press the [SAVE DATA] softkey (F1).  
Press the [SAVE TRACE] softkey (F1).  
Press the [INTO FILE] softkey (F9).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter T1.DAT and then press the [ENTER] softkey (F1)  
Note that the AGILENT 35670A automatically increments a numeric ending to a file  
name. To store Trace B data to a file named “T2.DAT”:  
Press the [Active Trace] hardkey.  
Press the [ B ] softkey (F5).  
Press the [Save/Recall] hardkey.  
Press the [SAVE DATA] softkey (F1).  
Press the [SAVE TRACE] softkey (F1).  
Press the [INTO FILE] softkey (F9).  
T2.DAT will be the default name  
Press the [ENTER] softkey (F1)  
Confirming Contents of 3.5” Disk File  
To confirm that data was stored on disk successfully, view the contents of the disk  
with the catalog command:  
Press the [Save/Recall] hardkey.  
Toggle the [CATALOG ON OFF] softkey (F8) until ON is highlighted.  
The entire contents and file details of the disk are displayed. To return to the trace  
view:  
Toggle the [CATALOG ON OFF] softkey (F9) until OFF is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Saving Trace to Non-Volatile RAM (NV-RAM)  
To store Trace A data as a file named “N1.DAT” into NV-RAM, follow these steps:  
Press the [Active Trace] hardkey.  
Press the [ A ] softkey (F5).  
Press the [Save/Recall] hardkey.  
Press the [DEFAULT DISK] softkey (F9).  
Press the [NON-VOL RAM DISK] softkey (F9).  
Press the [Save/Recall] hardkey.  
Press the [SAVE DATA] softkey (F1).  
Press the [SAVE TRACE] softkey (F1).  
Press the [INTO FILE] softkey (F9).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter N1.DAT and then press the [ENTER] softkey (F1)  
Confirming Contents of NV-RAM  
To examine the contents of NV-RAM, turn on the catalog as follows:  
Press the [Save/Recall] hardkey.  
Toggle the [CATALOG ON OFF] softkey (F8) until ON is highlighted.  
To return to the Trace view:  
Toggle the [CATALOG ON OFF] softkey (F8) until OFF is highlighted.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 23 : Recalling Trace Data From 3.5” Disk or Non-Volatile Memory  
Recall trace data from a file in non-volatile RAM or 3.5” disk using the AGILENT  
35670A Save/Recall capabilities. Recalled data is placed in a data register where it  
can be viewed, plotted, printed, analyzed, or used to compare.  
Recall Trace From 3.5” Disk  
To recall data from a file named “T1.DAT” on a 3.5” disk into data register D1,  
follow these steps:  
Insert the 3.5” disk containing the data file into the AGILENT 35670A.  
Press the [Save/Recall] hardkey.  
Press the [DEFAULT DISK] softkey (F9).  
Press the [INTERNAL DISK] softkey (F3).  
View the contents of the 3.5” disk by turning on the catalog  
Toggle the [CATALOG ON OFF] softkey (F9) until ON is highlighted.  
Return to the Trace view  
Toggle the [CATALOG ON OFF] softkey (F9) until OFF is highlighted.  
Set up display format to view data register D1  
Press the [Disp Format] hardkey.  
Press the [SINGLE] softkey (F1).  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted..  
Press the [Meas Data] hardkey.  
Press the [MORE CHOICES] softkey (F9).  
Press the [DATA REGISTER] softkey (F8).  
Press the [D1] softkey (F1).  
Recall the Data into data register D1  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D1] softkey (F1).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter T1.DAT and then press the [ENTER] softkey (F1)  
Recall Trace Data from Non-Volatile RAM (NV-RAM)  
To recall data from a file stored in NV-RAM named “N1.DAT” into data register  
D2, follow these steps:  
Press the [Meas Data] hardkey.  
Press the [MORE CHOICES] softkey (F9).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [DATA REGISTER] softkey (F8).  
Press the [D2] softkey (F2).  
Press the [Save/Recall] hardkey.  
Press the [DEFAULT DISK] softkey (F9).  
Press the [NON-VOL RAM DISK] softkey (F9).  
Press the [Save/Recall] hardkey.  
Press the [RECALL DATA] softkey (F4).  
Press the [RCL TRACE AND SCALE] softkey (F1).  
Press the [FROM FILE INTO D2] softkey (F2).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter N1.DAT and then press the [ENTER] softkey (F1)  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 24 : Plotting and Printing Trace Data  
Use the plotting and printing capability of the AGILENT 35670A to generate  
hardcopy documentation of measurement results. Any trace can be documented,  
however to plot or print data stored on disk or in NV-RAM, the data must first be  
recalled into a Trace. To recall trace data from a file, see the section “Recalling  
Trace Data From 3.5" Disk or Non-Volatile Memory.”  
Generating Output with the AGILENT 35670A  
All traces displayed on the screen are output to the printer, plotter, or file. Therefore  
if it is desired to plot one trace at a time, then the SINGLE display format should be  
used. Complete control over the plotting and printing parameters is available from  
the front panel of the AGILENT 35670A. For plotting, choose pen color for grids,  
annotation, each trace, and each marker. Traces can each have their own line type.  
Describe the test with two lines of plot titles that will appear at the top of the plot. A  
date stamp can be selected to show when the data was acquired.  
Enter Trace A Title (if desired). Repeat for traces B, C, and D if displayed.  
Press the [Active Trace] hardkey.  
Press the [A] softkey (F1).  
Press the [Disp Format] hardkey.  
Press the [MORE] softkey (F9).  
Press the [TRACE TITLE] softkey (F7).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter a description of the Trace, for example the accelerometer location,  
such as “MACH 1 - Y” and then press the [ENTER] softkey (F1). Note  
that trace titles can be up to 13 characters long.  
Enter a plot title (if desired)  
Press the [Plot/Print] hardkey.  
Press the [MORE SETUP] softkey (F9).  
Press the [TITLE LINE 1] softkey (F7).  
Enter first line of test description, maximum 44 characters, then press the  
[ENTER] softkey (F1)  
Press the [TITLE LINE 2] softkey (F8).  
Enter second line of test description, maximum 44 characters, then press  
the [ENTER] softkey (F1)  
Plotting the Display  
To plot the current display, connect an GPIB plotter, with the plotter address set to 5,  
to the AGILENT 35670A. Then follow these steps:  
Press the [Local/GPIB] hardkey.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Select the [SYSTEM CONTROLLR] softkey (F2).  
Check the Plot/Print Destination  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DESTINATN] softkey (F4).  
Select the [OUTPUT TO GPIB] softkey (F1).  
Plot the Trace  
Place a sheet of paper in the plotter and locate P1 and P2, if not done  
automatically.  
Press the [Plot/Print] hardkey.  
Press the [START PLOT] softkey (F1).  
Printing the Display  
Results may be sent to a printer using the serial or parallel ports. The parallel port  
requires no setup. The serial port must be configured to match the parameters of the  
printer.  
Print over Serial Interface to Raster Device  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DEVICE] softkey (F3).  
Select the [RASTER PRINTER] softkey (F2).  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DESTINATN] softkey (F4).  
Select the [OUTPUT TO SERIAL] softkey (F2).  
Press the [Plot/Print] hardkey.  
Press the [MORE SETUP] softkey (F9).  
Press the [SERIAL SETUP] softkey (F9).  
Choose serial setup parameters that match the printer. With luck the  
default choices will already match the printer.  
Print over Parallel Interface to Raster Device  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DEVICE] softkey (F3).  
Select the [RASTER PRINTER] softkey (F2).  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DESTINATN] softkey (F4).  
Select the [OUTPUT TO PARALLEL] softkey (F4).  
Print the Trace  
Press the [Plot/Print] hardkey.  
Press the [START PLOT] softkey (F1).  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 25 : Importing Plots into Microsoft Word  
The plotter output of the AGILENT 35670A conforms to the HP-GL/2 Graphics  
Language. When the PLOT/PRINT output device is specified as a 3.5” disk file, not  
a printer or plotter, then the resulting graphics files can be imported directly into  
Microsoft Word using the Insert Picture command.  
Determining if MS Word Has HP-GL Graphics Import Filter  
Before importing a plot file, Word must have the HP-GL graphics import filter  
installed. To determine if it is, follow these steps:  
On a PC, start Microsoft Word or open a new document.  
Select Insert Picture  
In the “Insert Picture” dialog box, at the bottom, click on the arrow next to  
“Files of Type”.  
Scroll up and down the list, looking for “HP Graphics Language.”  
If “HP Graphics Language” is present, then the HP-GL filter is installed. If it is not  
listed, then you must use the Word Setup program to install the HP-GL graphics  
import filter.  
Installing the MS Word HP-GL Graphics Import Filter  
Run Word Setup, by running “a:setup” from 3.5” disks, Word or Office CD-ROM,  
and proceed as follows:  
After setup has initialized, select “Add/Remove” (components).  
In the Maintenance Dialog Box, click on the “Converters, Filters and Data  
Access” option.  
Click on the “Change Option” button.  
Click on “Graphics Filters”  
Click on the “Change Option” button.  
Scroll down to the HP Graphics Language entry. The check box next to  
it should be empty.  
Click on the HP Graphics Language check box.  
Click on the “OK” button.  
Click on the “OK” button.  
Click on the “Continue” button.  
Click on the “OK” button.  
The HP Graphics Language import filter has now been installed and activated. To  
make sure the filter has been installed,  
Return to Word.  
Select Insert Picture  
In the “Insert Picture” dialog box, at the bottom, click on the arrow next to  
“Files of Type”.  
Scroll up and down the list, looking for “HP Graphics Language.”  
It should now be an import option.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Plot to a File Using the AGILENT 35670A  
The AGILENT 35670A has the ability to route plotter output to a file. If the file is  
named with a “.HGL” file extension, then Word will recognize this file immediately  
as an HP Graphics Language file.  
Set up plotter output to a file  
Press the [Plot/Print] hardkey.  
Press the [PLOT/PRNT DESTINATN] softkey (F4).  
Select the [OUTPUT TO FILE] softkey (F4).  
Press the [OUTPUT FILENAME] softkey (F5).  
Press the [CLEAR ENTRY] softkey (F9).  
Enter P1.HGL and then press the [ENTER] softkey (F1)  
Insert a 3.5” Disk into the AGILENT 35670A and ensure DEFAULT DISK is  
INTERNAL DISK:  
Press the [Save/Recall] hardkey.  
Press the [DEFAULT DISK] softkey (F9).  
Press the [INTERNAL DISK] softkey (F3).  
Plot to file “P1.HGL”  
Prepare Trace Titles and Plot Titles as described in the section “Plotting  
and Printing Trace Data.”  
Press the [Plot/Print] hardkey.  
Press the [START PLOT] softkey (F1).  
Inserting Picture of an HP-GL Plot File Into a MS Word document.  
To import the plot file into the Word document, follow these steps:  
Insert the 3.5” disk with the plot file “P1.HGL” into a PC.  
Open a Word document  
Select Insert Picture  
Click on the “Look in” arrow to change directories  
Select A: (3½ Disk)  
Double-Click on file “P1.HGL”  
Word will automatically detect that it is an HP-GL file, because of the  
.HGL file extension, and import the graphic directly.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 26 : Running a Single Calibration Test on Command  
The AGILENT 35670A automatically runs periodic self-calibration tests which  
ensure that all measurements will meet published performance specifications. If a  
calibration is desired at a specific time, then a single caibration may be performed as  
follows:  
Press the [System Utility] hardkey.  
Press the [CALIBRATION] softkey (F2).  
Press the [SINGLE CAL] softkey (F3).  
The calibration will start immediately and be completed in less than 15 seconds.  
Section 27 : Returning the AGILENT 35670A to a Preset Condition  
The AGILENT 35670A can generally return from an unknown state to a preset  
condition by using the following command:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
This does not turn off the analyzer, but it does stop data acquisition and reset most  
measurement parameters. If the AGILENT 35670A is locked up due to a software  
bug and no response can be generated by the Preset key, then a hard shutdown may  
be required.  
Section 28 : Precautions to Prevent Loss of Data  
The most important aspect of preventing data loss with the AGILENT 35670A is to  
avoid interrupting data acquisition. This can happen as easily as by tripping on the  
power cord, but can also occur by accidentally re-starting a long measurement,  
prematurely triggering an event, overloading the front ends, or unplugging  
connectors.  
Two situations call for careful planning and precautions: the first is when  
frequencies are low and data acquisition times are very long, such as very low  
frequency seismic testing. An interruption may waste hours of data acquisition. The  
second situation worthy of precaution is when the test involves a one time event, like  
the initial run-up of large machine during a plant re-start, or like a crash test, where  
the test article is destroyed. In either case the data is valuable and care should be  
taken to save it to disk before the data is lost by another measurement.  
Manual arming along with a Channel 1 trigger and pre-trigger delay is the preferred  
technique of acquiring transient crash tests. The pre-trigger delay ensures that the  
entire transient event is captured even if the trigger is a little late. Manual arming  
prevents re-triggering and loss of data if the transducer encounters a post-test bounce  
or hit. Of course manual arming REQUIRES that the measurement be manually  
armed before the test, otherwise the measurement will not be armed and data will be  
missed.  
71  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 29 : Transducer Unit Conversion with the AGILENT 35670A  
Automatic conversion between acceleration, velocity, or displacement units is  
available with the Trace Coord capability in the AGILENT 35670A. Transducer  
sensitivity and transducer unit label is first specified for the input channel, then the  
desired unit is specified using XDCR UNIT CONVERSION.  
Measuring Acceleration, Displaying Displacement  
To set up and display a measurement of acceleration, proceed as follows:  
Press the green [Preset] hardkey  
Press [DO PRESET] softkey (F1).  
Press the [Input] hardkey  
Press the [FRONT END CH1 SETUP] softkey (F7).  
Press [ICP SUPLY ON OFF] softkey (F8) until ON is highlighted.  
Press the [Input] hardkey  
Press [XDCR UNIT CH1 SETUP] softkey (F8)  
Press the [XDCR SENSITVTY] softkey (F6).  
Enter 10.8, then press the [mV/EU] softkey (F2).  
Toggle the [XDCR UNIT ON OFF] softkey (F4) until ON is highlighted.  
Press the [XDCR UNIT LABEL] softkey (F7).  
Select the [g] softkey (F2).  
Specify an averaged measurement  
Press the [Freq] hardkey  
Enter 800 and then press the [Hz] softkey (F2)  
Press the [Avg] hardkey.  
Turn on averaging by pressing the [AVERAGE ON OFF] softkey (F1)  
until ON is highlighted.  
Press the yellow [Start] hardkey.  
After the measurement is complete, set up the display to show acceleration and peak-  
to-peak displacement simultaneously. RMS acceleration is already displayed on  
Trace A. Set up Trace B to show peak-to-peak displacement as follows:  
Press the [Active Trace] hardkey again.  
Press the [B] softkey (F2).  
Press the [Meas Data] hardkey.  
Press the [CHANNEL 1 2 3 4] softkey (F1) until 1 is highlighted.  
Press the [PWR SPEC CHANNEL 1] softkey (F3)  
Press the [Trace Coord] hardkey.  
Press the [Y UNITS] softkey (F8)  
Toggle the [AMPLITUDE PK PP RMS] softkey (F4) until PP is  
highlighted.  
72  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [XDCR UNIT CONVERT] softkey (F4)  
Press the [inch (DISP)] softkey (F7)  
Press the [Scale] hardkey.  
Toggle the [AUTOSCALE ON OFF] softkey (F1) until ON is highlighted.  
This accomplishes the equivalent of multiplying “g” by 386.4 to get “inches per  
second squared” (ips^2), and dividing by (jω)^2 to integrate twice in the frequency  
domain to get displacement.  
Math Functions and XDCR UNIT CONVERT  
When you have specified a “provided” transducer label using XDCR UNIT SETUP  
that is a “motion” engineering unit such as:  
g
inch/s^2  
inch/s  
inch  
mil  
m/s^2  
m/s  
m
then do not try to convert acceleration to displacement using Analysis: Math  
Function and divide by (jω). Instead use the above example to convert directly using  
XDCR UNIT CONVERT in Trace Coord, Y UNITS. If this is attempted with Math  
Functions, the analyzer will sense that a power spectrum of a known unit “label” is  
being integrated or differentiated and will do it using trace coordinates anyway. It is  
easier to use the provided capability in XDCR UNIT CONVERT.  
Converting Frequency Response Units to Compliance  
Unlike power spectrum measurements, frequency response measurements cannot be  
automatically converted into other units. Howvere, it is often desired to express a  
frequency response result as the ratio of displacement to force, which are units of  
compliance, instead of acceleration to force, which are units of 1/mass. To convert a  
frequency response measured as “g/lb.” into terms of “inch/lb.”, then proceed as  
follows:  
Converting “g” to “inch/s^2” requires multiplication by 386.4. This must be entered  
as a constant. Converting “inch/s^2” to “inch” requires double integration in the  
frequency domain by dividing by (jω) two times. These steps may be entered as  
follows  
Press the [Analys] hardkey.  
73  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Press the [DEFINE CONSTANT] softkey (F2).  
Press the [DEFINE K1] softkey (F1).  
Enter 386.4 and press the [ENTER] softkey (F1).  
Press the [Analys] hardkey.  
Press the [DEFINE FUNCTION] softkey (F1).  
Press the [DEFINE F1] softkey (F1).  
Press the [CONSTANT (K1-K5)] softkey (F3).  
Press the [CONSTANT K1] softkey (F1).  
Press the [ * ] softkey (F3).  
Press the [OPERATION] softkey (F5).  
Press the [MORE] softkey (F9).  
Press the [ /jOMEGA( ] softkey (F4).  
Press the [OPERATION] softkey (F5).  
Press the [MORE] softkey (F9).  
Press the [ /jOMEGA( ] softkey (F4).  
Press the [MEAS DATA] softkey (F1).  
Press the [FREQ RESP 2 / 1] softkey (F5).  
Press the [ ) ] softkey (F5).  
Press the [ ) ] softkey (F5).  
Press the [ENTER] softkey (F7).  
Now display the function F1 on Trace B  
Press the [Active Trace] hardkey.  
Press the [B] softkey (F2).  
Press the [Meas Data] hardkey.  
Press the [MORE CHOICES] softkey (F9).  
Press the [MATH FUNCTION] softkey (F7).  
Press the [PWR SPEC CHANNEL 1] softkey (F3)  
Press the [F1] softkey (F1).  
Trace B will now convert “g/lb.” into “inch/lb.” This same technique could also be  
used to convert “g” into velocity terms, or to convert between metric and English  
units.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 30 : Using the Agilent Technologies Demostration Unit with the AGILENT  
35670A  
Several of the sections in this User’s Guide are best explained with live data using  
transducers and machines. Because it is usually impractical to bring machinery into  
a laboratory for training purposes, the Agilent Technologies Demonstration Unit  
with the Dynamic Signals Test Disc #1 (The Red CD) provides a practical  
alternative.  
This section describes the AGILENT Demonstration Unit and how to use it. The  
most important strating point is to MAKE SURE THE DEMONSTRATION UNIT  
IS GROUNDED TO THE AGILENT 35670A! This can be done via software by  
grounding Channel 1 via the Input, FRONT END CH1 SETUP. Alternatively a  
BNC can be connected from the AGILENT 35670A Source output to the Demo  
Unit’s notch filter.  
To set up the Demonstration Unit, follow these instructions:  
1. Plug in the Discman power supply and insert the power connector in the  
receptacle on the back of the Demonstration Unit.  
2. Insert the Dynamic Signals I CD in the Sony Discman, close the cover and press  
the play/pause button.  
3. Refer to the summary below to determine, for each section of the User’s Guide,  
the recommended track, port to connect the left CD output channel, and port to  
connect the right CD output channels.  
4. Select track repeat mode (Play Mode 1) by pressing the PLAY MODE button on  
the front of the Discman twice until “1” appears in the Discman’s LCD display  
75  
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AGILENT 35670A  
Supplemental Operator’s Guide  
above the track number.  
The following descriptions link the Section in this User’s Guide to the appropriate  
CD track. Also described herein is the recommended CD output channel connection  
to the AGILENT 35670A. Finally any setup clues will be described to help utilize  
the signals on the CD.  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 4:  
Measuring a Single Channel Spectrum  
CD Track:  
24  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
160 kHz Calibration Tone  
N/A  
Channel 1 of the AGILENT 35670A  
Section 5:  
Improving Measurement Results  
CD Track:  
24  
CD Track Desc:  
Left Ch. (A Out):  
Right Ch. (B Out):  
160 kHz Calibration Tone  
N/A  
Channel 1 of the AGILENT 35670A  
Section 6:  
Measuring a Single Channel Time Waveform  
CD Track:  
24  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
160 kHz Calibration Tone  
N/A  
Channel 1 of the AGILENT 35670A  
Section 7:  
CD Track:  
Measuring Dual Channel Spectra  
41  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Current Probe, Tachometer  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
Section 8:  
CD Track:  
Improving Dual Channel Measurement Results  
41  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Current Probe, Tachometer  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
Section 9:  
CD Track:  
Measuring Dual Channel Time Waveforms  
41  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Current Probe, Tachometer  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
77  
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AGILENT 35670A  
Supplemental Operator’s Guide  
Section 10:  
Measuring Dual Channel Spectra and Time Waveforms  
CD Track:  
41  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Current Probe, Tachometer  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
Section 11:  
CD Track:  
Modal Testing Using a Hammer and Accelerometer  
44  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Hammer Measurements on a Brake Rotor  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
Section 13:  
CD Track:  
Order Domain Results in List Mode  
28  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Setup Hints:  
Car Engine Run-up and Tachometer Signal  
Channel 1 of the AGILENT 35670A  
TACH input on the back of the AGILENT 35670A  
Pulses per rev: 2  
Tach. Trigger level: 0.15 V  
Section 16:  
CD Track:  
Waterfall Spectra at RPM Intervals  
28  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Setup Hints:  
Car Engine Run-up and Tachometer Signal  
Channel 1 of the AGILENT 35670A  
TACH input on the back of the AGILENT 35670A  
Pulses per rev: 2  
Tach. Trigger level: 0.15 V  
Section 18:  
Measuring Frequency Response with the AGILENT  
35670A  
CD Track:  
58  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Burst Random Frequency Response Measurement  
Channel 1 of the AGILENT 35670A  
Channel 2 of the AGILENT 35670A  
Section 20:  
CD Track:  
Peak Hold During a Machine Run-up  
28  
CD Track Desc.:  
Left Ch. (A Out):  
Right Ch. (B Out):  
Setup Hints:  
Car Engine Run-up and Tachometer Signal  
Channel 1 of the AGILENT 35670A  
TACH input on the back of the AGILENT 35670A  
Pulses per rev: 2  
78  
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