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Audio Masking
Homepage Crypto Spy radio Burst encoders Intercept Covert Index Glossary Cameras Recorders Radio Bugs Microphones Earpieces Optics Concealments Dead drops Tools Stories Software Tracking Radio PC Telex Telephones People Agencies Manufacturers DONATE Publications Standards For sale Kits Shop News Events Wanted Contact About us Links × Audio masking Audio masking, or just masking , is a technique that is often used with covert listening devices , or bugs , for hiding the intelligence of the intercepted audio (e.g. human speech), from a casual or professional interceptor.
By injecting a very strong 50 Hz hum into the baseband, it was hoped that a sweep team checking the room for bugs, would discard it as interference from a domestic applience or a transformer. When using it in combination with a directional antenna, such as the HE-100, the spectrum in the building or room under investigation can be searched for the typical fingerprint of the SRT transmitter, which consists of a 6 to 10 MHz wide carrier and several sidebands at either side. A quick test with the portable Audiotel Delta-V differential RF detector, shown in the image on the right, immediately revealed the presence of a bug in the room.
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