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The cost of digital processing microchips has made sophisticated techniques, such as video motion detection systems far more accessible. We’ve been looking at VideoTracker, a relatively low-cost upgrade, that can be easily incorporated into existing surveillance equipment



In the past few years video motion detection has become one of the fastest growing surveillance technologies. Most of the advances are a a result of recent  developments in digital video processing microchips. Several mid-range cameras and related video products now incorporate motion sensing facilities as standard, but until recently it has been either impractical, or too costly to upgrade a system.


It’s not difficult to see why video motion detection has become such an important surveillance tool. In many cases it removes the need for separate activity sensors -- allied to individual cameras. Moreover they can be more sensitive and more selective than conventional PIR detectors, giving the installer and end-user more control and flexibility.


VideoTracker from Primary Image is a good example of the new generation of video motion sensors, now coming onto the market. It’s a small, fully self-contained,  stand-alone device, designed to be used with a single camera channel, or networked with other VideoTrackers in multi-camera set-ups. It connects between the camera and other any devices (switcher, VCR, monitor etc.), operating independently, but with the facility to interface with peripheral devices, via a set of alarm contacts. This can be used to alert an operator, trigger a VCR, or activate an alarm.


It’s built inside a compact extruded alloy case measuring just 110 x 165 x 33mm, (roughly the size of a VHS cassette), and is powered by a separate plug-in mains adaptor. It has three video connections, using panel mounted BNC sockets. One is for video input, from the camera, there’s a loop-through video output for connection to other components in a CCTV system, and the third carries the ‘Tracker’ display, for display on a monitor. The other connections are a set of screw terminals for the alarm output (NO, NC and common), and two multi-pin terminals, for networking two or more VideoTrackers together. There are just two LED indicators, green for normal operation, red for alarm activity, plus two simple controls: one is for adjusting sensitivity, the other is sued to enable or disable the Track Display video output.


Installation takes just a few moments, and the loop-through facility means it can be incorporated into an existing system, without minimal disruption. Movement within the scene is highlighted by white rectangles of varying size, superimposed onto the video output of the Tracker display, that track with the person or object. Sensitivity is set using a small rotary switch, there are 16 positions. At its most sensitive it reacts to any movement of an object, corresponding to just 2% of screen height. The minimum setting responds to moving objects of up to 12% of screen height. The factory default setting is a good compromise, and it will ignore small amounts of movement --  foliage on a tree or bush etc. -- but will trigger if a person or vehicle enters the scene. The only other adjustment (also using a rotary switch) blanks out the Tracker Display whilst there’s no activity; when triggered the display is enabled for a period of 20 seconds, or continuously, or for as long as the activity continues. In addition to the switched contacts on the alarm terminals, there’s a 12 volt DC and 0 volt reference, so it can be used with a wide range of equipment   


The range of sensitivity adjustment is such that it can be used with a camera on a pan/tilt mount; the unit can be set to ignore the relatively slow movement of the camera, and only respond to more rapid activity. In use it runs quite hot, and it should be mounted in a well ventilated position.



VideoTracker works best on largely static scenes, if the activity exceed the minimum sensitivity setting it just gives up. It is most responsive to changes in contrast, and consequently, is more effective with black and white cameras. Used with a colour camera it sometimes has difficulty detecting movement where the colour of the subject or object is similar to the background.  It has no difficulty compensating for slow changes in scene lighting, though a light switching on for example, will trigger the alarm, so some care needs to be taken with installation and alignment when the VideoTracker is used to monitor outdoor scenes..



The key benefits are the ease with which VideoTracker can be integrated with an existing system, and flexibility of operation. From an installation standpoint the unit could do with some mounting brackets or supports; simply leaving a module to float around on top of a console, rack or other equipment is unsatisfactory and just asking for trouble. Operationally there’s little to complain about, though  a couple of points come to mind. A lot of video motion sensors have the facility to screen out parts of the scene, which can be very helpful, where, for example, the intention is to monitor a doorway or entrance, and ignore other parts of the image. A further enhancement would be to have an internal alarm buzzer, though in both cases we’re aware of the need to keep down costs, and in that context VideoTracker has a significant advantage over rival products.




Video system                            PAL or NTSC

Video in                                    1.0V p-p, 0.3 volt sync (PAL)

Video out (loop-through)            1.0V p-p, 0.3 volt sync (PAL)

Monitor/Track Display 1.0V p-p, 0.3 volt sync (PAL)



Relay contacts              24 volt DC.1.0A (NC/NO/common)


Connections                              Video in/out (BNC), alarm contacts (screw terminal), networking (multi-pin connectors), DC power (DC socket)


Power                                       12 volts DC/1.0A, mains power adaptor supplied



Dimensions                               110 x 165 x 33mm





Product design            8

Build quality                  9

Ruggedness                  9



General functions            8

CCTV functions            8         

Ease of use                   9

Instructions                   8

Manuf. support                          



Track  accuracy            9

Video stability            9



Ó R. Maybury 1996 1509




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