The Sony Guide to
CCTV
Issue
3
this is not a rehearsal.
Introduction
In recent years...
there has been no shortage of innovations in the CCTV
industry with manufacturers competing to better meet
the needs of crime prevention. Most visibly, more
surveillance cameras have appeared in more public areas
than ever before, proving their effectiveness and generating
interest in maximising the benefits of operating a surveillance
system.
The bewildering choice of different equipment and the desire for practical
knowledge in this area demonstrates that, as with most disciplines, a little research
into the subject will yield higher quality decisions and an improved cost/benefit
ratio. It is intended that this Guide should assist you to ask the right questions and
direct you towards the best possible solution.
The generalised use of crime statistics, of which there are many varieties, conceal
the fact that every situation is different and requires a tailored approach. Most
businesses, for example, take an economic approach to the use of security measures
– how much will a system cost and how much loss will it prevent? An often quoted
but nevertheless true precept is that businesses, particularly retail, often
underestimate the true extent of losses. The importance of conducting a detailed audit
and survey before even considering technology cannot be over-emphasised.
Where CCTV is used in town centre schemes, the principal objective is to
improve the quality of life for the inhabitants by reducing actual and perceived
crime. Continuing Government support for video surveillance in public areas reflects
the value of a properly specified scheme and its place in providing information for a
measured police response.
To be an effective deterrent, the system must provide actual as well as
theoretical results and be introduced as one part of an overall crime prevention
initiative. Where this ‘system credibility’ has been established, the greatest benefits
have been derived.
Included in this Guide are some examples of highly credible surveillance
schemes where the users have achieved the maximum benefit from their systems,
together with detailed background information on the selection and operation of
CCTV. We have also included information about how new technology is offering
higher levels of performance in video surveillance than ever before.
Brian Kelly,
Marketing Manager, CCTV & Components
Sony Broadcast & Professional UK
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case study
Sony gives Newham
a clearer picture
Newham District Council has the largest local authority CCTV control room in
the country, monitoring over 200 cameras in the heart of London’s East End.
Recently, it has installed additional Sony Trinitron colour video monitors, bringing
the total in the system to 73 screens. As well as fighting crime, the system is used
for traffic surveillance, including monitoring a new bus lane system, controlling
vandalism, general council activity and ensuring local authority response to
maintenance problems.
The Newham Control Room is also the first in the country to use facial
recognition technology and has recently acquired a Sony Mavica digital camera.
The camera is being used in the prevention of doorstep fraud to build up a
database of employees for the production of ID cards.
The new colour video monitors – nine SSM-20N5E
and two SSM-14N5E – were chosen for their
clarity and sharpness of picture – particularly
suited to surveillance monitoring. The
Trinitron CRT (Cathode Ray Tube), which
has upgraded resolution from a typical
250 to 600 lines, gives a markedly
crisper and more stable image. The
face of the Trinitron is based on the
shape of a cylinder rather than a sphere
ensuring that not only is the geometry of
the image more accurate, but operator
eye-fatigue is reduced.
Operations Manager Bob Lack explains: “The
Council has a policy of making the best use of the technology currently available
and with the help of optimum funding obtained through the CCTV Challenge
scheme and support from local businesses, we have invested £2 million in the last
four years.
“We already had 54 Sony SSM-20 and eight SSM-14 monitors in the system,
some of which were installed when the control room was first set up five years
ago. As the control room monitors are never switched off, durability has also been
an important factor.”
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The Sony Guide to CCTV Issue 3
case study
Underground
Security
Expanded
The latest phase in London Underground’s
multi-million pound refurbishment programme
includes the installation of 60 Sony CCTV
cameras at three of South London's busiest
central stations: Brixton, Pimlico and Vauxhall.
Part of an integrated passenger security system, pictures from the cameras at all
three stations can be selected and received at a specially built control room at the
Brixton station where Sony S-VHS time-lapse VCRs are located, providing real-time
recording when necessary.
At Vauxhall and Pimlico, individual control rooms are also equipped with two
Sony recorders set in real-time mode, which receive pictures from their own
station cameras.
The SSC-DC50P CCD colour cameras are line-fed, simplifying installation by using
a single coaxial cable to send both video and sync signals. Chosen for their high
degree of resolution and identification capability, the cameras are located on
platforms, in passages and ticket halls as well as close to the new Help Points where
customers can communicate with London Underground staff (or with British
Transport Police).
As British Transport Police Public Affairs Manager, Simon Lubin explains, crime on
the Underground has reduced by 22 per cent since 1990 with one important
contributing factor being the installation of CCTV throughout the system.
“CCTV is a vital weapon in the police armoury helping to prevent and deter crime,
as well as to detect it. Our customer surveys show that CCTV also reassures people
travelling and is an important investment by London Underground in passenger and
staff security.
“Officers are using CCTV daily as a key investigative tool to trace and confirm
identities of suspects, as well as to obtain evidence for presentation in court. If it is
to perform those functions effectively, picture quality has to be as high as possible.”
The SSC-DC50P cameras use digital signal processing and Sony HyperHAD
technology to achieve high quality pictures in the most demanding circumstances.
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For more information contact the Sony Business Information Centre: 01932 816340
case study
Daewoo savings
with Sony PMS
In the face of rising manned guarding costs, Daewoo Cars has installed a new
remote surveillance alternative – a monitoring codec from Sony.
Daewoo was spending over £1 million a year on manned guarding services for its
25 forecourt and showroom sites until a remote video monitoring service
introduced a complete design, commissioning and monitoring package based
around remote CCTV surveillance.
Daewoo's brief was to protect
vehicles and premises while
allowing customers free access to
the forecourt even after showroom
hours. At the same time there had
to be an obvious deterrent and the
means to identify criminal activity
and summon assistance.
Key to the effective running of
the system has been a pilot of the
Sony PMS 400/500 at Daewoo’s
Slough showroom.
The Sony Codec is designed to
control CCTV equipment and
transmit information from any
number of remote sites, in the form
of high quality pictures and audio,
to a central point using a dial-up
ISDN telephone line. The use of the
ISDN line eliminates the
considerable costs associated with
the laying of cables for
transmission, such as fibre optics.
Any suspicious activity on a
Daewoo forecourt or in the
showroom, such as attempts to steal car radios, trim or wheels, can now be quickly
identified, confirmed and acted upon from the central monitoring station.
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The Sony Guide to CCTV Issue 3
case study
Farsight Chooses
the HSR-1P
One of the UK’s largest remote video monitoring
companies has chosen the Sony HSR-1P to replace
its existing complement of time-lapse video recorders and multiplexers.
On a weekly basis Farsight (UK) Ltd, based in Peterborough, makes and receives in
excess of 20,000 video patrols/alarms from its diverse mix of clients situated
throughout the UK.
Farsight is currently using two HSR-1P digital surveillance recorders and 40
DV270 tapes to meet all its recording requirements. Farsight Operations Manager,
Paul Dadford, explains: “Traditionally, all video was recorded to VCR. However, as
each video receiver requires a VCR and at least 30 tapes, retrieving video data from
archive was a time-consuming, inefficient and labour-intensive task.”
Farsight’s R&D department was therefore tasked to provide a recording solution
that would reduce the time taken to retrieve archive video and reduce the overall
effort required to manage video recording across 14 video receivers.
Four digital surveillance recorders were chosen for evaluation. Only the HSR-1P
provided a complete integrated solution with the digital recording cached to hard
disk and then copied to the integral DV tape.
Paul Bromley, Farsight IT Manager, says the HSR can be linked with Sony’s PMS
video transmission system, allowing both units to be controlled from one software
platform giving a totally integrated solution. “The use of DV technology gives the
HSR-1P an impressive storage capability. The system is easy to use, compact and
extremely robust.”
The integration of the DV tape also had unexpected benefits, in that software
written at Farsight to log the incoming and outgoing video patrols, now controls the
HSR-1P directly, enabling retrieval of archive video footage in minutes instead of
hours as was the case with the old VCR recording system.
“Instead of wading through banks and banks of video cassette tapes, I only have
to enter the time and date in search mode and the incident is immediately retrieved.
Additionally, the unique Sony water-mark on every recorded frame gives our client
base a guarantee that no digitally stored information has been tampered with.
“The introduction of the HSR-1P has enabled us to provide better quality video
recording for our clients while at the same time reduce the overall work required to
administer a complex video recording system.”
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For more information contact the Sony Business Information Centre: 01932 816340
What is Closed Circuit
Television?
Closed Circuit Television (CCTV) is a television system which operates on a
‘closed loop’ basis. Unlike broadcast television, which is available to anyone
with a suitable receiver, CCTV pictures are only available to those directly
connected to the loop.
Colour Video Monitor
Video Out
(Coaxial cable)
DC12 V
DC12 V
AC outlet
power supply
CCTV was first used in the 1950s and has since become an essential element in
any professional security system.
In most installations, the loop is a physical link – a cable which carries the
picture from the camera to the viewer. With very few exceptions, the pictures are
transmitted as a composite video signal at 75ohms, 1 volt peak-to-peak. Where
very high resolution (>400TV lines) is required, some equipment offers a Y/C facility
where the luminance signal (Y) and the chrominance (C) is divided. Over long
distances, for example in Town Centre systems, fibre optic transmission has
become popular. Where this option is too expensive, ISDN offers a cost-effective
alternative for event-driven surveillance systems.
As well as the full range of property protection and control applications, CCTV
offers benefits in many other areas, for example:
■ Assisting police authorities in the monitoring of traffic flow and the
implementation of prompt action in case of accidents and other emergencies
■ Supporting process industry managers as they control the flow of work, identify
production bottlenecks and take corrective action
■ Monitoring of hostile environments that are not accessible to man, i.e. nuclear
reactors, furnaces, etc.
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The Sony Guide to CCTV Issue 3
When and where
should it be used?
Security and surveillance are the most accepted applications for CCTV
systems. With the use of CCTV, managers and supervisors can control risks
and minimise costs efficiently and with the minimum of disruption.
Security applications
As well as acting as an effective deterrent, CCTV helps managers to monitor:
■ Access to secure areas
■ Unauthorised activities
■ Theft or criminal damage
■ Personal safety
Surveillance applications
CCTV has many applications in public safety:
■ Traffic control
■ Alarm Verification
■ Crowd control
■ Insurance claim assessment
■ Public access
■ Staff control
■ Car park security
■ Shopping precinct security
■ Industrial process control
Benefits
CCTV offers increased efficiency and the faster
detection of problems. As a result, its benefits include:
■ Reduced security running costs
■ Faster response to problems
■ Increased peace of mind
■ Simplicity and reliability
■ Improved quality of environment for owners, operators and the public
■ Easier identification of suspects
■ Increased management control
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For more information contact the Sony Business Information Centre: 01932 816340
Light
The human eye and the camera lens operate on completely different lines.
Although the human eye adjusts automatically to various light conditions,
the camera is inherently less flexible.
In a CCTV system, lighting has to be ‘designed in’ from the beginning if the best
results are to be obtained. The type of lighting used, and the correct positioning, are
vital to maximum security.
Everyday ‘white light’ is actually a mixture of colours of different frequencies.
CCTV is more receptive to certain colour combinations than others. The best results
are usually obtained by matching the spectral response of the camera to the light
illuminating the scene.
The amount of light reflected from an object determines how ‘bright’ it appears.
Here are some typical reflective figures:
Asphalt
Foliage
Concrete
5%
10-20%
25-30%
Red Brick 35%
Snow 95%
These figures relate to the minimum level of lighting required for security purposes
to everyday light. It can easily be seen that today’s CCTV technology will give good
results under very low light levels. Sony ‘Exwave’ cameras can operate in colour as
low as 0.8Lux (F1.2) without switching to monochrome or reducing frame rate.
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The Sony Guide to CCTV Issue 3
Light
LUX*
DESCRIPTION
50,000
British summer sunshine
5,000
500
300
50
Overcast sky
Well lit office
Minimum for easy reading
Passageway/outside working area
Good main road lighting
Sunset
15
10
5
Typical side road lighting
Minimum security risk lighting
Twilight
2
1
0.3
0.1
0.001
0.0001
Clear full moon
Typical moonlight/cloudy sky
Typical starlight
Poor starlight
*Metric unit of measurement of light.
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For more information contact the Sony Business Information Centre: 01932 816340
Light
Backlight Compensation
It is also important to consider whether there are bright spots in the picture such as
car headlights which can make identification of the vehicle registration or model
impossible.
This can also be a major problem where it is necessary to identify persons who
are moving from bright daylight into artificial light. Very often this will result in the
subject becoming an unidentifiable silhouette. The problem is exacerbated where
bright spots in the images cause vertical smearing.
The answer is to specify a camera which has effective backlight compensation.
This can be operated automatically by Smart Control within the camera or, where
the position of the subject is pre-determined, can be pre-selected.
It is helpful to be able to see how effective the backlight compensation is before
making final camera selection.
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The Sony Guide to CCTV Issue 3
Choosing a
Camera
The camera is the ‘eye’ of a CCTV
system and at its core lies CCD
(charge coupled device) technology.
The CCD is comprised of about 500,000 light sensitive cells called picture elements
(pixels) which convert the light falling onto its surface into an electrical signal. The
performance of the camera, and ultimately the surveillance system, is more
dependent upon the quality of the CCD than any of the other camera components.
Currently, the popular formats are:
■ Half-inch
High performance for high sensitivity and low noise
Most popular and ideal for a wide range of applications
A more recent development
■ Third-inch
■ Quarter-inch
Benefits of CCD Technology
■ Long Life
Produced with a design life of up to 10 years
■ Shock Resistant
■ Size and Weight
■ Spectral Response
Much more rugged than older tube technology
Have enabled the miniaturisation of cameras
Responsive in the near infra red area
Pixels (Picture Elements)
■ Total Pixels
This is the total number of pixels on the CCD faceplate.
They are not all usable
■ Active Pixels
This is the real figure giving the number of pixels
that are actually in use
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For more information contact the Sony Business Information Centre: 01932 816340
Choosing a Camera
Sensitivity
Colour cameras generally perform less well in low light than monochrome cameras,
all other things being equal. Sensitivity is usually measured by reference to the lux
level at which a camera can produce an image (see page 9).
The lux valuation, although usually referred to as a metric unit of measurement
of light, is very often applied subjectively to the ability of a camera to produce
images.
Comparisons based on the lux levels given by different manufacturers do not
usually lead to a valid determination. A more valid comparison can be made where
the F-stop of the lens is also quoted together with the video level, although the best
solution is to make a live visual evaluation of the cameras under consideration.
i) Lux level at the face plate
This measures how the camera performs when all light falls directly on the chip
faceplate. Whilst technically valid, this never actually happens. You cannot get a
picture unless you use a lens and the lens cuts down the available light.
ii) At the lens
This is closer to the specification we are looking for because it goes some way to
describing the specification in real life.
Which lens?
The lower the ‘F’ number of the lens used the better the result. For example:
■ Camera one quotes 0.8 lux full video with an F1.0 lens
■ Camera two quotes 0.8 lux full video with an F1.2 lens
Camera two is the more sensitive camera as it quotes 1 lux with a slower F1.2
lens. With the faster F1.0 lens, it would probably give a full video signal at only
0.6lux.
Colour Rendition
Any assessment of a camera’s operating capabilities should include how accurately
it can reproduce colour. If, for example, a target subject is dressed in a brown
jacket and blue trousers it will not be helpful for the police if they are looking at a
CCTV image of a person apparently wearing an orange jacket and turquoise
trousers. This will also have severe limitations on the evidential value of such an
image. Cameras offering better colour rendition will have both auto and selectable
white balance to handle varying lighting conditions.
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The Sony Guide to CCTV Issue 3
Choosing a Camera
Camera Resolution
The higher the resolution the sharper the picture. The best resolution available at
present for CCD cameras is approaching 750 horizontal lines (TV lines) (3-CCD,
DXC-950P) and 500 vertical lines.
Resolution is not necessarily the key decision point. Low resolution CCTV, which
is usually lower cost, is often perfectly adequate and the final choice depends on
the combination of camera features and build quality together with site conditions
and available funds. As a general rule, a high resolution is preferable in low light
levels and when identification of points of fine detail are required.
Sony ExwaveHAD CCD Technology
A key question to consider is whether colour or black and white cameras should be
selected. Not many people now watch black and white television in their homes – a
colour picture is easier to interpret, provides more information and is more natural
than a monochrome one.
In surveillance applications, the split currently between colour and monochrome
is about 50/50. In recent years, the price difference between the two has
diminished. The principal limiting factor against the use of colour cameras has been
the ability of colour cameras to operate effectively in poorly lit areas.
To meet this demand for colour images in low light, manufacturers have
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For more information contact the Sony Business Information Centre: 01932 816340
Choosing a Camera
developed a range of
solutions, the most
Hyper HAD CCD
Ineffective area
popular of which include
hybrid cameras that
operate in colour when
lighting is adequate,
switching to monochrome
as darkness falls. Some
cameras operate in low
light by reducing the
number of frames
Transfer register
Exwave HAD CCD
Hole accumulated layer
captured to produce a
brighter picture although
this causes problems
when there is movement
within the image.
Sony has developed a
more radical approach by
improving the sensitivity
of the CCD chip. On Chip
Lens technology (OCL)
increases the surface
area and sensitivity of the
CCD by locating a microlens on each pixel which results in more light being
collected on the photosensitive layer. This technology has been developed most
recently with the introduction of the ExwaveHAD CCD which has a highly advanced
OCL structure. The result of these developments is a degree of sensitivity that can
handle twilight light levels while still producing accurate colour images even with
rapidly moving objects.
Smear is caused by the leakage of light onto the vertical shift register, creating
a vertical bar across the image which can render it useless and is a common
problem with cameras in low light or where there are bright spots in the picture.
With ExwaveHAD, this leakage is reduced because the improvement in the
structure of the CCD minimises the undesirable reflection of light onto its surface.
As a result, smear is reduced to a minimal level of -120dB – comparable to the
frame interline transfer CCDs commonly used in broadcast cameras.
Sony now produces both colour and monochrome cameras which benefit from
the advanced technology of ExwaveHAD technology.
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The Sony Guide to CCTV Issue 3
Selecting the
Correct Lens
The quality of the lens is vital in determining the quality of the final image.
The basic optical characteristics of a lens are the focal length (in zoom lenses
the focal length range) or angle of coverage, and the aperture range. We’ll
look at these two characteristics together with a third important
characteristic, the format.
Focal Length (F)
The focal length represents the distance from the optical centre of the lens to the
point at which the image is in sharpest focus and where the pick-up device in the
CCTV camera is located.
The focal length determines the angle of coverage of the lens. The longer the
focal length, the narrower the angle of coverage and the shorter the focal length,
the wider the angle of coverage.
One particular angle of coverage produces a picture very similar to that seen by
the human eye. A lens giving this angle is called a ‘normal’ lens. The focal length of
a normal lens is approximately equal to the diagonal of the picture area. For
example, for a 2/3 inch camera, the normal lens would have a focal length of
16mm. A 1/2 inch camera would have a normal lens of 12.5mm and a 1/3 inch
camera, an 8mm normal lens.
A focal length shorter than a normal
focal length produces a wide angle
view. A longer focal length
produces a telephoto image.
Some lenses have variable
focal lengths and are called
zoom lenses.
d
F
Basic Lens
F = Focal Length
d = Lens Diameter or Aperture
f = Lens Stop Expressed as a ratio
of Focal Length to Aperture
F
d
f =
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For more information contact the Sony Business Information Centre: 01932 816340
Selecting the Correct Lens
Aperture range
The aperture is the clear opening in the centre of the lens that allows light to pass
to the pick-up device.
The aperture size is described in relation to the focal length (F). Thus the
aperture is specified by an F number. If the lens has a focal length of 50mm and if
the diameter of the clear opening of the lens is 25mm, then the lens is said to have
an aperture of F:2 (50mm divided by 25mm = 2). A 50mm lens with an aperture of
F:2 has the same light gathering ability as a 150mm F:2 lens but the glass
components will be more complex in order to achieve the telephoto effect.
Most CCTV lenses have a built-in mechanism called an iris. This allows the
aperture to be changed to accommodate varying light levels. The largest aperture
setting is often used to define the maximum light gathering capability of the lens,
the lens speed. A lens with a maximum aperture of F:1.6 is referred to as an F:1.6
lens and is said to be ‘faster’ than, say, an F:4.2 or F:8 lens.
The iris setting of the lens is numbered from the largest F stop down to the
smallest F stop. CCTV systems are rarely installed in situations where light levels
are constant, so lenses with automatic iris adjustment are important components of
most systems.
Focus set to 20m.
Lens f = 1.4
Depth of Field
Depth of Field
Lens f = 5.6
Depth of Field
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The Sony Guide to CCTV Issue 3
Selecting the Correct Lens
Another characteristic of lenses is the ‘depth of field’ (see illustration). If a lens is
focused on an object there will be a certain area of sharp focus in front of and
behind the object. The depth of this area of sharp focus is controlled by three
factors: the focal length of the lens, the distance from the lens to the object
and the F stop.
Lens Format
The lens format relates to the camera format, 1/3 inch, 1/2 inch, 2/3 inch.
There are two lens mounting systems. Most CCTV cameras have a ‘C’ mount,
although many now use a ‘CS’ mount. ‘C’ mount cameras are not able to use ‘CS’
lenses, however adaptors are available.
To avoid the complexities of lenses with automatic irises, manufacturers have
developed ‘electronic shutters’. These achieve the same light adjustment with
simpler, fixed iris lenses. The CCD iris common to most Sony CCTV cameras
automatically controls image exposure by electronically adjusting the incoming
light levels.
Cameras with Built-in Lens
Some cameras are now available with a built-in lens. Sony manufactures a 1/3 inch
colour camera with an integral 5.4mm - 64.8mm zoom lens (SSC-CX34P) which
can be used in place of the conventional camera and motorised lens set-up. This
saves installation time and the resultant set-up is lighter, allowing the use of more
compact camera housing and pan and tilt head.
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For more information contact the Sony Business Information Centre: 01932 816340
Which Monitor?
A control room operator may be required to view images on a bank of
monitors for prolonged periods. As the effectiveness of the surveillance
system is crucially dependent upon the degree to which the operator can
remain alert and avoid fatigue, correct monitor selection is vital.
The monitor converts the video signal generated by the camera back into a visual
image. It consists of a cathode ray tube (CRT) and a number of signal processing
circuits.
These circuits separate the ‘luminance’ part of the signal from the ‘sync signals’.
The luminance signal is routed to an amplifier, which boosts the signal to a level
that can be used by the CRT. The sync signals are split onto horizontal (H) pulses
and vertical (V) pulses. These in turn are amplified and modified so that they can
control the vertical and horizontal deflection of the final picture.
Where the video signal is being looped through the monitor to another piece of
equipment (for example, another monitor or video recorder), it is important to
ensure that the system is correctly terminated. Some monitors will do this
automatically, but others have a switch located at the rear. This should be set
according to whether the signal is being looped out of the monitor – High
Impedance – or is terminating, in which case it should set to 75 ohms.
The last item of equipment in the system should be set to 75 ohms if it does not
auto terminate. Video signals usually travel over coaxial cable, which has
impedance of 75 ohms. The best and most efficient transfer of the video signal
from camera to monitor is when the camera, cable and monitor all have all the
same impedance values. Contrast levels can be improved where a DC clamp facility
is incorporated into the monitor. This can usually be selected via a switch at the
rear of the unit.
Monitor sizes
Monitor size is designated by the length of a diagonal line measured from one
corner of the viewing screen to the opposite corner. Thus a 9-inch monitor refers to
a 9-inch diagonal picture tube. Sizes typically used in CCTV include 9, 12, 14, 17,
21 and 27 inches with different manufacturers offering different variants.
The choice of size depends in part on the distance between the viewer and
monitor.
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The Sony Guide to CCTV Issue 3
Which Monitor?
CCTV monitors may be
free standing,
Monitor Size
Typical Viewing Distance
9˝
suspended from a wall
or ceiling, or rack
12˝
17˝
21˝
mounted. Wall and
ceiling mounts allow the
monitor to be rotated
and tilted for viewing
from different angles.
5´
10´
15´
Monitor costs
Why does a 17-inch black and white CCTV monitor cost more than the equivalent
black and white TV? The answer is that the CCTV monitor has specialist features
and characteristics. For example, the average TV set has around 300 lines of
resolution while the CCTV monitor would normally have over 700 lines. The CCTV
monitor also has regulated power supply to maintain performance during power
fluctuations, an isolation transformer and a fast acting automatic frequency control
(AFC) loop to reduce radio frequency interference.
Colour monitors
Colour monitors are also available in a similar range of sizes. These monitors
usually accept only composite colour signals, although where very high quality
images are required, monitors with a Y/C (luminance and chrominance) input
should be used.
Two principal types of colour CRTs are currently in use: the shadow mask CRT
and the Trinitron. The face of the shadow mask type is based on the shape of a
sphere, whereas the Trinitron is based on
the shape of a cylinder. This means that
the Trinitron is curved only in the horizontal
plane providing an image which is more
geometrically accurate and which reduces
operator eye-fatigue caused by reflected
light from above. Close examination of the
shadow mask CRT reveals how the image
is constructed from dots or ellipsoids
whereas the Trinitron images consist of
continuous stripes resulting in a cleaner
and more stable image.
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For more information contact the Sony Business Information Centre: 01932 816340
Transmission of
Video Signals
A CCTV signal contains a wide range of frequencies from around 30 hertz to
around 10 Megahertz. As a result special circuits are required to cope with
the wide band-width if signal quality is to be maintained during transmission.
Because signals from CCTV cameras often have to travel long distances to reach
the control centre, the choice of transmission medium depends upon the particular
installation and its requirements.
Coaxial Cable
P.V.C. Outer Protective Sheath
Braided Copper ‘Outer’ Screen
Polythene Insulation
‘Inner’ Copper Conductor
Coaxial Cables
The most widely used cable is the coaxial type. It should have characteristic
impedance of 75 ohms and be of a high quality. The cable consists of an ‘inner’
solid copper conductor or twisted copper wires surrounded by a flexible insulating
material such as polythene. It is recommended that for CCTV a solid polythene type
coaxial should be used to give maximum high frequency performance. The ‘outer’
conductor consists of a copper braid wound around the insulation. To protect the
cable from moisture and damage, it is covered with a tough PVC sheath.
Sony CCTV cameras can be powered via the Triple Multiplex transmission
system, to ensure maximum ease of installation. With this system, the video signal
from the camera, the sync signal and the DC power are all supplied via a single
coaxial cable.
The Sony system also allows for cable lengths of more than 600 metres without
any loss of image quality.
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The Sony Guide to CCTV Issue 3
Transmission of Video Signals
Twisted Pair
An alternative to the use of coaxial cable is the ‘twisted pair cable’. A twisted pair
cable is known as a ‘balanced’ cable and can be similar to telephone wires. Most of
the same considerations apply to twisted pair as apply to the coaxial but there are
some expectations. The twisted pair system will accept the standard 75 ohms, 1
volt composite video signal and convert it to a balanced video signal of 2 volts
with an output impedance of 50 to 150 ohms to suit the particular twisted pair
being used.
The approach is relatively inexpensive and can transmit over longer distances
than conventional coaxial cable. The major disadvantage is that transmitter and
receiver units are required for every video signal source. This is because units such
as monitors which process base band video signals will not accept the balanced
twisted pair type of transmission.
Fibre Optics
Fibre optic transmission of video signals is now widely used within the CCTV
industry, most particularly on large projects such as town centres. Optical fibres are
fine strands of glass with a high quality of optical transparency which act as wave
guides for light beams. They have lower transmission losses than conventional
cables and are virtually immune to electrical interference.
Developments in laser technology have made optical fibre a useful means of
video transmission. The video signal modulates the laser beam, which is then
transmitted through the fibre. Picture quality remains excellent over distances
greater than 50km.
ISDN Transmission
An increasingly popular method of transmitting video signals is to use ISDN. This is
a digital phone line which transmits video signals at 128 kilo bits per second. The
signals are encoded at site, transmitted across the telephone network, and then
decoded at the monitoring centre. These systems are event driven which means
that they only transmit video when an event has occurred – for example a break-in
at a property activates a PIR which then causes the transmitter to dial the
monitoring centre which can then take appropriate action.
These systems do not provide live video images because of bandwidth
constraints but some systems, like the Sony PMS-500 Codec, can transmit up to 15
frames per second. The PMS-500 can also transmit and receive full duplex audio,
together with data signals for control of telemetry and other remote devices via the
RS232 and RS485 communication ports.
21
For more information contact the Sony Business Information Centre: 01932 816340
Transmission of Video Signals
Personal Computer
Local
Remote
RS232C
ISDN
PMS-400P/500P
PMS-400P/500P
These devices facilitate a flexible range of applications and are increasingly being
manufactured to international standards H.320 & H.261 (ITU-T recommendation).
.
22
The Sony Guide to CCTV Issue 3
Video Switching
and Multiplexing
If a system consists of a single camera and monitor, then a switching device
will not be required. It would not, of course, be practical or desirable in a
multi-camera system to have a monitor for every camera. In these cases, a
switcher will enable the video signal from several cameras to be viewed on
just one monitor.
Time Lapse VCR
(ex. SVT-L230P)
Video Camera 1
Video OUT
(coaxial cable)
Video OUT
Video IN
Video INPUT
1 to 16
SW OUT
Rec
PB
IN
OUT
Alarm IN
Alarm OUT
Mon 1 OUT
YS-DX316P/
DX216E
Colour Video Monitor
(ex. SSM-20N5E)
Video OUT
(coaxial cable)
Video Camera 16
Mon 2 OUT
Colour Video Monitor
(ex. SSM-20N5E)
Switchers
Manual switchers are the most basic form. Here, the operator selects the camera
they wish to view. Automatic switchers are the most popular versions. These run a
sequence of displays in the order that the operator selects. The operator can also
hold one particular camera if he wishes to observe some relevant activity, can skip
channels if they do not at that time require monitoring, and adjust the dwell time
for each camera. Automatic switchers also normally have an alarm programming
option which can override any manual settings.
23
For more information contact the Sony Business Information Centre: 01932 816340
Video Switching and Multiplexing
Multiplexers
Multiplexers are a more functionally useful way of handling a multi-camera system.
Like a switcher, several cameras (usually up to 16) can be connected to the
multiplexer. A single field or frame from each camera is successively output via the
multiplexer onto a video recording. Playback would take place again via the
multiplexer which would decode the recording to the monitor.
So, for example, if four cameras were connected to the multiplexer, on playback,
the particular camera to be reviewed would be selected and an updated image
produced every 0.87 seconds (Sony YS-DX316P and SVT-5050P). The more
cameras that are recorded onto one tape, the fewer images per camera are
captured – if eight cameras were connected, that refresh rate would extend to one
image every 1.73 seconds.
In the majority of cases, these types of refresh rates provide sufficient
information to enable incidents to be reviewed effectively. Problems may arise if the
video recorder is a time-lapse machine recording many cameras over long periods.
For example, if 16 cameras were recorded over 72 hours you would have to wait
9.87 seconds for the image from each camera to be updated. It is therefore
important to ensure that an acceptable ratio of cameras to multiplexers/VCRs is
utilised.
Duplex multiplexers can display in multi-picture mode at the same time as
recording, as above. Simplex multiplexers can either record or display, but cannot
do both simultaneously.
.
24
The Sony Guide to CCTV Issue 3
CCTV Systems Control
While the majority of cameras are installed in a fixed position, in order for the
operator to be able to follow an incident it can be very useful to have the
facility to pan, tilt and zoom the camera.
This is achieved by the use of a mechanical pan and tilt head on which the camera
is mounted and a zoom lens which are controlled remotely by telemetry signals. As
in most instances the camera will be fitted outdoors and therefore it will be
necessary to use a housing which will protect it from the elements or to use a
dome camera.
Telemetry
There are two types of electronic telemetry: one uses a twisted pair, where long
distances are involved; the second uses coaxial cable – in fact, the same cable that
carries the video signal. The basic form of telemetry control system uses digital
techniques to produce a pulse code modulated (PCM) signal. This is a signal which
has a series of 16 pulses and, depending upon the function required (pan/tilt or
zoom), sends the appropriate pulses to a receiver which interprets them and carries
out the function.
Housings and Enclosures
These protect the CCTV camera/lens assembly. Used in both internal and external
applications, housings also protect against dust, vandalism and extreme weather
conditions.
Many different housings are available with accessories, such as thermostatically
controlled viewing windows, sunshields, blowers for hot environments and heaters
for use in extreme cold.
Domes
Domes operate in much the same way as a conventional pan, tilt and zoom camera
except that they are generally more compact and have the added advantage of
being discreet – both aesthetically and for the purpose of surveillance. It is not
usually possible to see in which direction the camera within the dome is directed.
Conventional housings score over domes in terms of robustness and there is less
chance of the optical distortion created by the spherical dome cover.
25
For more information contact the Sony Business Information Centre: 01932 816340
Recording
While a proportion of surveillance systems are continuously monitored, these
are in the minority. The majority of systems are not actively monitored and,
even when they are, in most cases, the images are still recorded.
The underlying principle to be considered in relation to the recording of images is
that they may ultimately be required as evidence in criminal proceedings. Despite
sometimes poor quality recordings, many spectacular successes have recently
been achieved in the detection and conviction of serious offenders, thanks to the
existence of recording material.
Analogue Recording
The preferred medium for recording and storing activity has been, and still is, VHS
videotape, usually recorded on a time-lapse video cassette recorder (VCR). These
machines are very similar to domestic video recorders but have extended record
and playback facilities, time and date encoding and alarm inputs.
The extended recording facility is achieved by reducing the frequency of fields
that are recorded, thereby extending the recording period of the tape. The number
of fields is further reduced when the VCR is recording multiple cameras from, for
example, a multiplexer.
VHS VCRs record around 300 TV lines horizontal resolution in monochrome and
240 TV lines in colour. The requirement to record higher resolution images has led
to an increase in the use of Super-VHS VCRs which record about 400 TV lines.
These are recommended where it is intended to record vehicle registration
numbers or other fine points of detail.
VCRs have many moving parts which require regular service to maintain
performance. For this reason, it is recommended that VCRs are serviced once a
year.
Digital Recording
Increasing demand for higher quality, more flexibility and lower maintenance has
encouraged manufacturers to develop recording equipment which more closely
matches the needs of surveillance systems.
This new technology is based on digital processing and storage and, in most
cases, produces higher quality images than analogue systems. Greatly increased
storage capacity also allows higher picture refresh rates and selectable resolution
modes. Camera inputs are multiplexed, stored on a hard disk and, periodically
.
26
The Sony Guide to CCTV Issue 3
Recording
DV Tape Drive
DV Signal Transfer
Hard Disk Drive
HSR-1P Recording Process
archived to Digital Video (DV) tape. Resolution modes of up to 500 TV lines can be
accessed which are simply not possible on conventional analogue VCRs.
The evidential value of digital recording has been considered by a distinguished
committee of Law Lords who have concluded that the same procedural
requirements which apply to analogue recording are also applicable to this more
recent technology.
Video Printers
A useful part of larger systems – a printer can produce hard copy images either
from live or recorded cameras.
27
For more information contact the Sony Business Information Centre: 01932 816340
Sony CCTV Products
Colour CCD Cameras
SSC-DC50/54/58AP
SSC-DC10/14/18P
SSC-C104/8P
ExwaveHAD, half-inch, 470 TVL, 0.8Lux
Third-inch, 470 TVL, 1.7Lux
Third-inch, 330 TVL, 1.2Lux
SSC-CX34P
Third-inch, 470 TVL, c/w 12x motorised
zoom lens
Monochrome CCD Cameras
SSC-M370CE
Half-inch, 570 TVL, 0.3Lux
Third inch, 570 TVL, 0.25Lux
ExwaveHAD, third-inch, 570 TVL
Third-inch, 380 TVL, 0.1Lux
SPT-M304/308CE
SPT-M320/324/328CE
SPT-M122/4/8CE
.
28
The Sony Guide to CCTV Issue 3
Sony CCTV Products
Colour Video Monitors
SSM-14N5E
Trinitron,14-inch, 600 TVL, Y/C and audio
SSM-20N5E
Trinitron, 20-inch, 600 TVL, Y/C and audio
Trinitron, 9-inch, 250 TVL
SSM-9040P
Monochrome Video Monitors
SSM-930CE
9-inch, 750 TVL, DC clamp
SSM-125CE
12-inch, 750 TVL, DC clamp and dual
inputs
SSM-175CE
17-inch, 850 TVL, DC clamp and dual
inputs
SSM-Q177CE
17-inch, 850 TVL, built in quad processor and
sequential switcher
29
For more information contact the Sony Business Information Centre: 01932 816340
Sony CCTV Products
Time-Lapse Video Recorders
SVT-124P
24-hour compact VHS
SVT-1000P
72-hour VHS, RS-232C option
SVT-L230P
72/96 hour VHS, ‘RealAction’,
RS232C option
SVT-5050P
SVT-S3050P
SVT-RS1A
SVT-RM10
TPK-Series
960-hour VHS, RS232C option
168-hour Super-VHS, RS-232C option
RS-232C Interface Board
Wired Remote Control
10,000 hour service kits for all VCRs
ISDN Transmission
PMS-500P
Transmitter/receiver codec
Transmitter codec
PMS-400P
.
30
The Sony Guide to CCTV Issue 3
Sony CCTV Products
Digital Surveillance Recorder
HSR-1P
DV-based, up to 6,480,000 image storage
capacity, built-in 16 channel multiplexer
Multiplexers
YS-SX210CE
YS-SX310P
YS-DX216CE
YS-DX316P
Mono, simplex, 10 channel
Colour, simplex, 10 channel
Mono, duplex, 16 channel
Colour, duplex, 16 channel
Quad
YS-Q440P
Colour, 4 channel
31
For more information contact the Sony Business Information Centre: 01932 816340
Basic CCTV Terminology
APC
CCTV
Adaptive Picture Control. VCR function which
automatically detects the condition of the
recording head and the video tape and then
sets the optimum record head current to
prevent over-modulation.
A Closed Circuit Television System which is
for private purposes only, and not for public or
general broadcasting.
CODEC
Short for coder/decoder. An ISDN transmission
system designed to the international
teleconferencing standard, H.320.
AGC
Automatic Gain control. Usually a switchable
circuit that allows the camera to provide a
‘useable’ picture during low light levels. You
can generally tell when the circuit is operating
because the picture appears to be ‘grainy’.
CONTINUOUS STRIPE PHOSPHORS
Method employed within Trinitron monitors to
increase brightness and resolution over
conventional dot pattern CRTs.
AMBIENT LIGHT
C MOUNT
Lighting level that is normal for a certain area.
It generally does not alter. It also can mean
the background light level of a certain area.
The industry standard type of screw threaded
lens mount.
CS MOUNT
Same thread as C-mount.
APERTURE CORRECTION
Switchable correction circuit which sharpens
the image of a picture electronically.
COMPOSITE VIDEO
1. A video signal in which the luminance and
chrominance components have been combined
(encoded) as in NTSC, PAL or SECAM.
2. A video signal obtained by combining parts
of at least two video signals, for example by
keying or matting.
AUTO IRIS
Causes the aperture of a lens to automatically
adjust to varying light levels, thus providing a
constant picture.
BNC
Commonly used video connector for
composite video.
CROSS TALK
Electrical interference caused by
electromagnetic or electrostatic couplings
from nearby conductors or external sources. It
can also refer to interference between two or
more signals in close proximity within a
bandpass.
BALANCING LINE
A circuit for transmission of video signals
which are equal in voltage, but of opposite
polarity.
BANDWIDTH
A value which expresses the difference
between the upper and lower limits through a
range of frequencies.
CRT
Cathode Ray Tube. Means by which the
picture is displayed on a monitor.
BLACK LEVEL
dB
A measurement of a video signal that
matches a specified maximum limit for black
peaks in the picture.
Decibel, a ration of input power. It is also a
measurement of sound levels.
DARK CURRENT
Leakage signal from a CCD sensor in the
absence of incident light.
CCD
Charge Coupled Device. The latest technology
for imaging devices. There are two main
types: Interline transfer and Interframe
transfer.
DARK NOISE
Noise caused by the random nature of the
dark current.
.
32
The Sony Guide to CCTV Issue 3
Basic CCTV Terminology
DEPTH OF FIELD
HAD SENSOR
The distance between the furthest and
nearest points at the same level of definition
within a certain view.
An improved type of semi-conductor sensor
which gives cameras a better smear and
noise performance.
DIGITAL VIDEO
HDR
A video storage media using 5:1
compression method.
Hard Disk Recorder. A device which
captures images to hard disk.
DWELL TIME
HSR
Amount of time that a sequential switcher
allows between the viewing of the different
cameras connected to it.
Hybrid Surveillance Recording. A combination
of hard disk and Digital Video in one recording
machine which greatly increase the storage
capacity over HDR.
EXWAVEHAD
Trademark of latest Sony Hole Accumulated
Diode charge coupled device.
HYPER HAD
An improved version of the Sony HAD sensor,
using on-chip lens technology to provide
increased sensitivity.
ELECTRONIC SHUTTER
CCD iris which eliminates the need for an
auto iris lens. The CCD iris automatically
controls the light intensity by adjusting the
electronic shutter speed.
IMAGE INTENSIFIER
Device which uses photo multiplier
technology to amplify the available light to
increase the sensitivity of a camera.
FRAME
A single television or film image. In European
television, 25 frames per second is used to
give an illusion of continuous movement.
Each frame in TV is normally two fields.
ISDN
Integrated Services Digital Network. Digital
phone line with transmission speeds of up to
128Kb per second. Used with PMS video
transmission systems.
FOCAL LENGTH
Distance from the optical centre of a lens to
the focal plane. Generally referred to in
millimetres.
INFRA-RED
A range of frequencies just below the
visible spectrum. Can be used for the
transmission of information or for providing
additional illumination for cameras.
FOCAL POINT
Point at which light passing through a lens
is concentrated.
INTERLACE 2:1
Scanning process for reducing the image
flicker consisting of successively scanned
lines which adjacent lines belong to
different fields.
F STOP
Figure given of the ratio between a lens
aperture and its length.
GAMMA
LINE FED CAMERA
See Triple Multiplex.
Unit of measurement for one amount of
contrast in an image.
LINE LOCK
Method of synchronising AC powered
cameras.
GENLOCK
A means of locking a video source to a
second video source or reference signal.
LUX
GROUNDLOOP
Metric unit of measurement of light.
A condition that occurs when two or more
grounded points in an electrical system
develop a conductive loop between them.
MEGASTREAM
A network (normally fibre optic) allowing
the transmission of data at 1Mbits per second
or faster.
33
For more information contact the Sony Business Information Centre: 01932 816340
Basic CCTV Terminology
MECHANICAL FOCUS
Focusing of a camera lens or pick-up device
by mechanical means.
wavelengths of light. Typically between the
ultra violet and infra-red spectrum.
SYNC GENERATOR
MONOCHROME
Device that produces a synchronisation signal.
Black and white picture comprising of a
number of levels of grey scales.
SUPER-VHS
VCR recording system that enables recording
of 400 TV lines horizontal resolution as
compared with ordinary VHS of 240 TV lines.
MULTIPLEX
Method of transmitting or recording many
video signals at the same time.
TELEMETRY
ND
Electronic method of controlling functions,
such as pan, tilt, zoom, focus, generally via
coaxial cable or a twisted pair of fibre optic.
Neutral Density. Filter which is positioned on
the rear of the lens, enabling the camera to
operate in difficult lighting conditions, by
widening its operating parameters.
TIME LAPSE
Video cassette recorder which allows the
compression of real time recordings onto tape
using time lapse mode. Can be up to 960
hours onto a single hour tape.
PEAK TO PEAK
Value between the maximum positive and
negative points on a waveform.
PIXEL
TRINITRON CRT
A word derived from Picture Element. This is
the smallest unique point of digital video
image. In digital video, a picture is divided up
into thousands of Pixels, each specified by
luminance, chrominance and position
information.
Cathode Ray Tube which is completely flat in
the vertical plane to enable better monitor
image geometry.
TRIPLE MULTIPLEX
A transmission of video, sync and DC power
over a single coaxial cable.
REAL ACTION RECORDING
VERTICAL PHASE
Feature on some AC cameras to adjust line
lock and synchronise multi-camera system.
High density VCR recording which provides
three times as many fields as conventional
time-lapse VCRs.
VHS
RESOLUTION
Video Home System domestic video recorder
format giving 240 TV lines horizontal resolution.
The definition of a TV picture in terms of the
finest detail that can be recorded and played
back.
WATERMARKING
Technical method of ensuring the integrity of
images recorded digitally.
RS232/485
Serial Interface commonly used to commu-
nicate between different control equipment.
WHITE BALANCE
Term which only applies to colour cameras.
Where white is the reference to determine all
other colours in the visible spectrum.
SMART CONTROL
Developed by Sony in 1994, this digital
technology allows Sony cameras to
automatically adjust iris, gain, white balance
and flicker to external lighting conditions.
Y/C
Method of separating and transmitting video
signals divided into Chrominance C (colour)
and Luminance Y (brightness) for higher
resolution and quality. Usually employed
between multiplexer/recorder/monitor.
SEQUENCE SWITCHER
A switcher that displays camera pictures in a
set order and dwell time, predetermined by
the user.
ZOOM RATIO
SPECTRAL RESPONSE
Term where the lens has moveable elements.
For example it is generally defined as 6:1 or
10:1 (i.e. 12.5 – 75mm or 10 – 100mm)
This is the response of the light sensing
(charge coupled) device to different
.
34
The Sony Guide to CCTV Issue 3
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CTVG 3
The Sony Guide to CCTV
Issue 3
Written by: Brian Kelly
Edited by: Carey Green
Designed by: Peter Courtley
Sony Publications Manager: Jackie Cook
Sony Broadcast & Professional UK
A Division of Sony United Kingdom Limited
The Heights
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