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WITNESS CCD OBSERVATION SYSTEM

 

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WHAT OUR EXPERTS SAY...

 

The success of products such as Philips Pro-Vision and Mitsubishi Mel-Guard over the past five years has clearly demonstrated there is a steady demand for easily installed, off-the-peg multi-camera video observation systems. This niche has been created by small businesses and residential users, who do not require heavily featured systems, that may be technically over-qualified and economically unviable for this kind of application.

 

The Witness CCD Observation System from Electronics Line, has clearly been designed to meet the needs of this increasingly important sector. The basic package comprises a 12-inch monochrome monitor with built-in camera switcher; it comes supplied with a single monochrome line-powered camera plus mounting bracket and 20 metres of pre-wired connecting cable. In addition to power and video signals, the cable also carries two-way audio between the monitor and the camera module, plus alarm information from optional PIR sensors.

 

The switcher can accommodate up to four cameras, they connect to the monitor via a bank of modular phone-jack sockets, on the rear of the case. Two similar sockets are fitted to the back of each camera; one connects the camera to the monitor, the other is for an associated alarm sensor. In addition to extra cameras and sensors the monitorís video output can also be connected to a VCR for recording and playback. Although not featured on our sample we understand all new models are now fitted with a slave monitor output. Other options include a weatherproof housing for the cameras, and extension leads, that can increase cable runs up to 100 metres.

 

CUBIC CAPACITY

The cube-shaped cream-coloured monitor measures 304 x 282 x 308mm. Most of the controls are grouped together on the front panel. Thereís a line of seven buttons and LED indicators, for manual camera selection, engaging auto-sequence, selecting VCR input and press-to-talk for two-way audio contact with a camera. Next to that thereís four preset controls for adjusting brightness, contrast and volume, and  setting the camera dwell time, which can be from 1 to 30 seconds. Thereís a small loudspeaker behind a grille on the left side of the fascia, the microphone is mounted just below the main on/off switch.

 

Around the back thereís a row of five modular jack sockets, one for each camera, the fifth carries VCR input and output, a suitable modular jack-to-phono/RCA adaptor lead is supplied. Additionally there are two recessed presets, for adjusting  vertical and horizontal hold. Unfortunately the holes on the back panel on our sample didnít quite line up, making it difficult to carry out any adjustments.

 

The monitor is fairly well built with a sturdy metal chassis and cover, that should be able to withstand a fair amount of punishment. The general standard of construction is quite good, though some aspects of the internal layout could be better, including the position of the mains transformer, which is very close to the side of the case. In fact itís close enough for the transformerís shielding to come into contact with the metal outer cover. The modular jack sockets do not appear to be very strong, the camera cables are quite heavy and look as though they could put the sockets -- and their soldered joints -- under quite a lot of strain; care needs to be taken to ensure the cables are not pulled.

 

CAMERA CHOICE

Two styles of monochrome camera are available. The standard issue item is a neat flat-pack design containing a board camera module and a second PCB for the audio and alarm functions.  The camera also houses a tiny 1.7-inch loudspeaker and electret microphone, itís quite crowded inside the box which measures just 62 x 75 x 35mm. The board camera is fitted with a fixed 4.3mm wide-angle lens; behind that thereís a  1/3-inch CCD image sensor with 315k pixel array, giving a low-light sensitivity of around 0.4 lux (f1.8); stated resolution is in the order of 400 lines. The exposure system is fully automatic, a high-speed shutter varies between 1/50th and 1/100,000th second.

 

The second  type of camera has a similar general specification but is a more conventional shape, and can be fitted with a C-mount lens. Cameras are supplied with a universal mounting brackets that can be fixed to a wall or ceiling. Any type of alarm sensor with an N/O contact can be connected to the second modular jack socket on the back of the cameras, Electronics Line can supply a suitable pre-wired PIR and adaptor cables for other devices. When the sensor is triggered the camera switcher is automatically overridden and an internal siren sounds in the monitor.

 

OPERATION

Alignment is very straightforward, there are no external user adjustments for the cameras; the only preliminaries on the monitor are to set the picture controls, volume and camera dwell time. As soon as the system is turned on the switcher is engaged and continues to operate until a camera selector button is depressed. The alarm system is activated by pressing a button on the back of the monitor -- not a very convenient location -- if  a connected alarm sensor is triggered the switcher stops and displays the relevant camera output. The alarm siren will also sound, this is cancelled by pressing the auto-sequence button on the front of the monitor.

 

Sounds picked up by the microphone on each camera are heard at the same time as the image is displayed; pressing the push to talk button allows the operator to be heard through the cameraís on-board loudspeaker.

 

At this point itís worth pointing out a couple of the systemís shortcomings. The most significant one being the lack of a switched alarm output, which would have enabled the system to be integrated with other security devices. This would have added very little to the cost, yet increased it functionality dramatically. The other feature we would have liked to have seen, would be a means of switching off the monitor screen, so that the switcher and cameras could continue to operate, whilst connected to a VCR.

 

IN USE

The cameras are unsynchronised, nevertheless, when the switcher changes from one camera to the next there is only a very slight jitter on the screen; this lasts for no more than one field. The picture is sharp and clean, contrast is good, and thereís plenty of detail. Picture alignment is fine and there is very little noise.

 

The images from the cameras are crisp and well defined, resolution on our test samples didnít quite manage the 400-lines resolution figure quoted by the manufacturer, though they werenít far short, at around 380-lines. Low-light sensitivity was within spec and although noise levels were quite elevated under those conditions, the image was still useable. At higher illumination levels noise is negligible. The fixed lens provides a wide angle of view, though there is a fair amount of barrelling at the edges.

 

The cameraís on-board microphone is very sensitive and can pick up a conversation -- in quiet surroundings -- at a distance of several metres. Needless to say the tiny loudspeaker built into the camera isnít very loud, itís just about okay if thereís no background noise but if the camera is mounted more than a half or metre or so away from the subject, itís a struggle to hear it. If the camera is fitted in the optional weatherproof housing the audio becomes even more muffled. Incidentally, the transparent window at the front of the housing can produce internal reflections when thereís a strong light source to the side of the camera.

 

OVERALL ASSESSMENT

The lack of a standby facility, so the system can continue to function with the monitor switched off, and an external alarm output, impose some limitations on flexibility. We suspect quality control could be better, and whoever decided to put the alarm enable switch on the back of the monitor needs their heads examining. Against that should be weighed the quite impressive performance -- comparable with similarly specified systems -- plus the lower than average cost of the basic system and add-on components. That firmly swings the balance in the Witness systemís favour and it deserves to do well.

 

PRODUCT ASSESSMENT

Design and design features              ****

Circuitry and components                  ***

Ease of installation and wiring    *****   

Range and variety of functions            ***     

Accompanying instructions                   ***          

Technical advice and backup            ****      

Value for money                         ****                           

 

 

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R.Maybury 1996 2403

 

 

 

 


 

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