Telecommunications – Receiver or analog modulated signal frequency converter – Responsive to an input signal of particular predetermined...
Patent
1987-04-01
1989-02-14
Griffin, Robert L.
Telecommunications
Receiver or analog modulated signal frequency converter
Responsive to an input signal of particular predetermined...
455 67, 455226, 342 20, H04B 1700, H04B 1100
Patent
active
048052310
ABSTRACT:
A method and apparatus for detecting a covert audio transmitter in which a microphone which picks up audio frequencies in the room and a radio receiver tuned to an unidentified audio signal are compared to determine if a "bug" is in the room being searched. An innocuous type of noise is introduced into the area to be searched by having persons converse or by turning on a radio, and these audio frequency signals are picked up directly by a microphone associated with the bug. The signal received by the bug causes the bug's RF carrier to be modulated, and this is picked up by the bug detector's radio receiver. The received signal is demodulated and is compared with the audio signal picked up by the bug detector's microphone to determine if the demodulated radio signal corresponds to the sounds in the room. If the demodulated signal from the detector's radio receiver matches the audio information picked up by the detector's microphone, an indicator light is lit to inform the operator that a bug is present.
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"Scanlock Mark VB", Publication from Technical Services Agency, Inc.
Griffin Robert L.
Smith Ralph E.
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