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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

 

 

---end---

Ó R. Maybury 1996 1101

 

 

 

 

 

 

 

 

 

 

 

 


 

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