Basic Countermeasures Equipment
VCD - VIDEO COUNTERMEASURES DEVICE
One of the more perplexing problems that has faced countermeasure technicians is the detection of video transmitters. Effective audio countermeasures have been around for some time. Probably the simplest form of audio detection is by the "feedback" technique. That is where the detector picks up the audio from the transmitter and feeds it to a loud speaker. The speaker, in turn, is heard by the microphone in the suspect device, amplified and retransmitted. The detection and retransmission process repeats itself rapidly and thus feedback is established.
Another simple audio detection mode is accomplished by placing a "known noise source", such as a radio or beeper, in the area being swept and listening for it through the countermeasure detector or receiver.
But what about video signals? A great deal of time and effort has been spent on actually viewing the signal to determine if it is of interest. Devices such as Raster Analysis Systems or broadband video demodulators have long been a part of the countermeasure scene but not everyone can afford or understand the use of these types of devices. Sometimes, the simpler, the better. Here is an easy way to tell if a video camera or transmitter is looking at YOU!
By using a lamp flasher (VCD). Place a lamp with a 60 to 100 watt bulb in the center of the search area. Turn on the lamp and make sure the bulb works. Unplug the lamp, plug it into the flasher (VCD) and plug the flasher into the power outlet. In a few moments the bulb will begin flashing. The flashing lamp becomes a visual "known noise source" instead of an audible one.
Turn off all the lights in the search area with the exception of a dim light source by which to work. Now, sweep the area with an RF detector. Any detected video signal (raster buzz) will produce audio which is synchronized with the flashing lamp as the video signal goes from white to black and visa versa. Once it has been established that the camera is looking into the search area, turn off the flasher and sweep the walls, etc. with a flashlight while listening to the detected raster buzz.
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