Bug -A hidden microphone, usually connected to a radio transmitter. Also, may be wired directly to a listening post.
Bumper Beeper - A radio transmitter which is attached to a vehicle for use as a beacon or homing device for tailing.
Carrier Current Device - Transmits a signal, modulated by audio, along a pair of wires (electrical or phone line) to a compatible receiver. The signal travels along the wires with very little radiated from the lines.
Contact Mic - A microphone that picks up sounds by amplifying vibrations from a solid surface such as a door, window or wall.
Harmonics - Multiples of a basic frequency. Their presence indicates a clandestine transmitter.
Hookswitch Bypass - A modification to the telephone instrument so that room sounds are picked up and passed down the phone line to a listening post even with the telephone handset hung up. Turns the telephone into a room bug.
Hot mic - See Hookswitch Bypass.
Jammer - A device that produces noise in hidden microphones, so that conversations are unintelligible to the listener.
Mail Cover - Interception of mail by the Post Office for a government agency.
Parallel Tap - Connected across both wires of a telephone line. Usually used to activate a tape recorder. DC resistance ranges from 10 megohms to 35 megohms. May also be a radio transmitter, in which case, a separate battery is required for powering the transmitter.
Parasitic Device - A type of eavesdropping device that pirates its operating power from a source such as the telephone line or house wiring. It requires no battery of its own.
Series Tap - Usually a radio transmitter. It obtains its power from the telephone line to which it is attached. It is installed in series (in line with one wire). Generally has a DC resistance of 70 to 300 ohms. Can also be used to activate a tape recorder.
Spike Mic - Similar to a contact microphone, but has a metal spike that is driven into a wall, etc. to pick up voice vibrations.
Tap - See Wiretap.
Wired Mic - An installation where a microphone is connected to a listening post by a pair of wires.
Wiretap - Clandestine interception of a telephone conversation. Operates when the phone is in use.
