GSQ-151 PSIDS Seismic Intrusion Detector

VN-Era Seismic Intrusion Detection System, consisting of
4ea. TRC-3A transmitters which identify themselves by the number of beeps they transmit upon detection, to 1ea. RC-3A receiver and earphone up to a mile away. Transmitters and receiver operate on a pair of 9V batteries in parallel. Detection radius of 10 meters nominal, depending upon sensitivity setting and soil conditions. 149.730 MHz