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TEKTRONIX TEST INSTRUMENTS
INTRO
The increasing sophistication of CCTV
technology has brought with it a growing need for equally advanced test and
measuring equipment. We’ve been looking at two portable instruments from
Techtronix now being targeted at the video surveillance market
COPY
Twenty-five years ago the only test equipment
many experienced security installation engineers ever needed was a neon screwdriver
and a damp finger, a few also ran to a multimeter, but in general life was simple...
Things have become a lot more complicated; you can’t get by with just a passing
acquaintance of Ohm’s law and an Avo meter anymore. Security technology has
advanced in leaps and bounds, especially with the proliferation of video surveillance.
Installation, alignment and fault-finding demands a considerable range of
skills and specialist test instruments.
The good news is that CCTV technology has become
a lot more reliable and installation is normally quite straightforward. Most
video systems have simple to follow set-up routines, and automated or pre-set adjustments,
but when things go wrong, they often do so in a spectacular manner. Fault-finding
can become very time-consuming, particularly when faced with complex multi-component
systems, with devices that interact with one another on several different
levels, that can make it extremely difficult to isolate a fault. Down-time is
not just frustrating for the end-user, it can result in a compromised security system,
with very serious consequences, so anything that makes a trouble-shooting
easier has to be welcome.
The need for specialised video test equipment
is not in doubt and there’s no shortage of products on the market, but most of
them are designed for static bench operation. They’re often far too cumbersome
to be of much use in the field, where conditions may be cramped and precarious,
or in a remote location with no access to a mains supply. Tektronix, one of the
world’s leading manufacturers of test and measuring instruments have long recognised
the need for rugged portable test equipment. Their range of video signal
generator and analysis systems includes devices designed for use in the
broadcasting and cable TV industry; broadcast and CCTV technologies share a
good deal of common ground so it’s reasonable to suggest that most general
purpose video test instruments are applicable to surveillance applications.
The two instruments we’re looking are here are
the TSG 95 ‘Pathfinder’ hand-held signal generator; and the WFM 90 signal
analyser. Potentially they have a wide range of uses, including alignment, verification
and testing of virtually all of the components and functions in a video surveillance
system, from a simple door-entry set-up, to a sophisticated multi-camera
installation with remote sites and recording facilities.
TSG 95 SIGNAL GENERATOR
It looks a bit like an oversize remote control
handset, measuring 56 x 91 x 191mm and weighing in at 0.68kg, with batteries. There
are no less that 41 buttons on the top panel but it looks a lot worse than it
is. Only a half a dozen or so are used in normal operation, the rest are
concerned with various set-up functions. Above the buttons there’s a small
illuminated LCD panel that shows mode, status and set-up information. The output
connections are mounted on the top-end of the case, there’s a male BNC for the composite
video signal, and two XLR sockets carrying line-level audio. It can be powered
from a variety of sources, including alkaline or re-chargeable AA cells, a 9.6
volt battery pack or a plug-in mains adaptor.
The TSG 95 generates a range of 20 PAL, 20 NTSC
and 21 Japan NTSC formatted video test patterns plus 14 pre-set and two user-definable
stereo audio signals. For the record the video patterns consist of two sets of
colour bars (100% and 75% modulation), either full-screen or split-screen with
a red field. It has a convergence grating, pluge, safe area delineation, red/green/blue
fields, 100/50/0% flat fields, multiburst, 5-step grey scale, 4.43 modulated
5-step scale, field square wave, bounce and a PAL signal Matrix.
Up to 26 PAL and NTSC test patterns can be combined
into a user-configured signal set. There are number of additional options,
including insertion of vertical interval test signals (VITS), and up to 8
superimposed ident message consisting of two lines of 16 characters; these may
be display singly, or sequenced, and the ident can be positioned anywhere with
the picture ‘safe-area’.
The audio signal generator produces 13 fixed
tones, from 50Hz to 20kHz, plus a sweep output and user-set frequencies. The
output level has four settings (-10, 0, +4 and +8 dB), ID ‘click’ sequences can
be added to either channel, to aid identification.
Despite the forest of buttons it’s very easy
to set up and use, though the use of XLR connectors -- a clear reminder of this
equipment’s origins in the broadcasting industry -- is slightly irritating as
it is rarely used on CCTV products and systems. A more fundamental problem is
the lack of an S-Video (Y/C) video output, which could prove to be a limitation
as the number of cameras and systems that utilise this signal format increases.
This is a quality item, rugged and well-built.
However, many of the test patterns have specialised applications that would be
rarely -- if ever -- be required on routine CCTV installations. Nevertheless, staples,
like colour bars, gratings and colour field signals are invaluable for a wide
range of tasks, including checking cable and microwave links, plus testing and
aligning control systems, switchers, VCRs and monitors.
FM 90 SIGNAL ANALYSER
The WFM 90 is a remarkably compact
combination of analytical instruments, that previously existed only as
stand-alone devices. It’s quite a handful though, the case measures 243 x 127 x
81mm and it weighs a hefty 1.4kg; it is fitted with a carry strap, so it’s reasonably
easy to hold one-handed. The key component is a high-performance 4-inch colour TFT
LCD screen. This acts as a display for a range of measuring instruments, that
include a vectorscope and what amounts to a dedicated oscilloscope, for showing
video and audio waveforms. The screen also acts as a colour monitor, checking
camera and VCR outputs or monitor inputs, and it has a facility to inset a
vector or waveform display into the monitor picture.
The main audio and video input and output
sockets are mounted in a recess at the top end of the case. They include three
male BNC connectors for the composite video input, (no S-Video facilities again
...), a second input for an external sync signal and a video output, for
connection to an external monitor or switcher. An XLR connector handles the single
audio channel input. On the right side of the case there’s a DC power socket
and 3.5mm minijack for a headphone output. Power is supplied by a 9.6 volt
battery pack, alternatively it can be fitted with 6 alkaline or nickel cadmium
cells.
Controls are simple and to the point. There are
basically five operating modes: video waveform display, vector display, audio
display, monitor and WIP or waveform in picture. Four buttons along the bottom
edge of the screen are used for mode selection of the various items that appear
on the display, that pop up when using the menu or configuration facilities.
The WFM 90 is even more exotic than the TSG
95 in that many of its functions are way beyond the everyday requirements of
CCTV installation and alignment. However, it’s worth taking a close look at what
it can do.
The video waveform display shows a specified picture
line, (chosen by pressing a pair of up/down buttons); the display can be moved
around the screen, using the four cursor buttons surrounding the ‘config’ key, and enlarged for inspection
or detailed analysis. There’s a number of additional display facilities, for
selecting one-line, two-line or two-fields, it also has a luminance-only (low
pass) filter, and variable gain. An alarm function changes the colour of the
waveform when the amplitude exceeds pre-set limits. Applications include
precise adjustment of video levels, matching video sync and burst levels on multi-camera
systems and setting lighting levels.
The vectorscope accurately depicts colour
values in terms of amplitude and phase, it’s a fairly sophisticated measurement
that has comparatively little bearing on most run-of the mill CCTV installations,
though it could conceivably be used to match the colour characteristics of some
advanced cameras, and setting colour balance on devices that have that
capability. The audio waveform display has only a very limited application on
systems with an audio capability. The human ear is still the most reliable and easy
to use sound measuring and quality control instrument!
The picture display mode is the major
justification for this device in a surveillance role. It’s useful to be able to
check camera outputs in the field, where it may be inconvenient or difficult to
use a conventional monitor. Picture performance is very good for an LCD screen,
though resolution is not as sharp as a CRT. It can be difficult to see the
screen clearly in bright or strong direct incident light; the optional viewing
hood could well be a necessity when used outdoors, on a sunny day. Colour rendition
is quite reasonable it’s capable of showing up moderate to serious colour aberrations;
more subtle errors can be difficult to see though. Arguably that’s a point in favour
of the vectorscope, though it would take a good deal of experience to be able
to identify a white balance error from the vector display alone; they’re far
easier to spot by eye, on a proper colour monitor.
SUMMARY
Two very sophisticated instruments. They’re superbly well made with outstanding
specifications, performance and pedigree. However, it’s fair to say that they’re
both rather over-qualified for this particular task. Their broadcasting heritage
is clearly stamped all over them, from the highly specialised test and analysis
functions, to studio-standard XLR connectors,
and the lack of S-Video inputs and
outputs. Within the context of the TV
broadcasting industry the price for both devices (£1000 for the TSG 95 and
£2000 for the WFM 90) is quite reasonable, but it would amount to a considerable,
possibly prohibitive investment for a
small to medium-sized installation company, who will have to weigh up the cost
of these instruments against cheaper and generally more appropriate
alternatives. Tectronix probably won’t object to us calling them the
Rolls-Royce of the portable test instrument market, but a Ford gets you from A
to B just as quickly and efficiently...
PRODUCT SPECIFICATIONS
TSG 95 PAL/NTSC SIGNAL GENERATOR
PAL test patterns: 75% colour bars, 100% colour bars, 75% bars over red,
100% bars over red, convergence, pluge, safe area, green field, blue field, red
field, 100% flat field, 50% flat field, 0% flat field, multiburst, 60% reduced
line sweep, 5-step grey scale, PAL modulated 5-step, Matrix, field square wave,
bounce
NTSC test patterns: SMPTE bars, 75% colour bars, SNG colour bars, convergence, safe
title/safe area, red field, 100 IRE flat field, 50 IRE flat field, black burst,
5-step grey scale, multiburst, NTC7 composite, NTC7 combination, FCC composite,
cable multiburst, cable sweep, sin (x)/x, matrix, 0 IRE no burst, field square
wave, bounce
PAL Characteristics:
Luma amplitude accuracy +/- 1% of 700mV
Chroma to luma gain +/- 2% of 700mV
Subcarrier stability +/- 10 Hz of
4.43361875 MHz
Frequency response to 4.8MHz,
flat within +/- 2%
to
5.8MHz, flat within +/- 3%
Power
DC input 9-15
volts
Typical battery life 7-10 hours
(alkaline)
3-4
hours (nicad)
General
Dimensions 191
x 91 x 56mm
Weight 0.68kg (inc batteries).
PRODUCT SPECIFICATIONS
WFM 90 WAVEFORM MONITOR
Waveform modes
Sweep modes 1H,
2H, 2V
Vertical gain 1X,
5X & variable
Filters flat,
luminance
Alarm waveform
colour change above 100 IRE
Vector Modes
Gain 1X,
5X & variable
Phase control 360
degree rotation
Bar amplitude 75% or 100%
Audio Mode amplitude/time
display, reference levels MIC, o, 4, 8 and 12dBu.
Power 12VDC, rechargeable battery pack included
General
Dimensions 243
x 127 x 81mm
Weight 1.4kg
(with batteries)
PSI RATINGS
TSG 95
Product
Product design 8
Build quality 9
Ruggedness 9
Operation
General functions 9
CCTV functions 7
Ease of use 8
Instructions 9
Manuf. support 9
Performance
Pattern accuracy 9
Pattern stability 9
WFM 90
Product
Product design 9
Build quality 9
Ruggedness 8
Operation
General functions 8
CCTV functions 5
Ease of use 7
Instructions 9
Performance
Image accuracy 7
Image stability 8
Image resolution 7
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Ó R. Maybury 1996 1101
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