Signal tracer For long pulse trains, a cyclic redundancy check may be calculated and displayed, giving the tech insight into the content of circuits that are switching rapidly. Signal tracer A signal tracer is a piece of electronic test equipment used to troubleshoot radio and other electronic circuitry. Usually a very simple device, it normally provides an amplifier, and a loudspeaker, often battery-powered and packaged into a small, hand-held test probe. An optional diode detector is usually also provided, allowing the detection of amplitude-modulated signals. The technician injects a test signal into the device under test. Then, by using the signal tracer,
The Thing (listening device) with a simple diode detector/demodulator, similar to some field strength meters. Two additional State Department employees, John W. Ford and Joseph Bezjian, were sent to Moscow in March 1951 to investigate this and other suspected bugs in the British and Canadian embassy buildings. They conducted a technical surveillance counter-measures "sweep" of the Ambassador's office, using a signal generator and a receiver in a setup that generates audio feedback ("howl") if the sound from the room is transmitted on a given frequency. During this sweep, Bezjian found the device in the Great Seal carving. The Federal Bureau of Investigation set about