Interrogator/receiver system for use with a remote transponder

摘要: Interrogator/receiver apparatus is disclosed for transmitting a first signal to, and receiving second from remote transponder. In the preferred embodiment, transponder passive, surface acoustic wave device which receives signal, processes this transmits, in reply, includes unique identification code. The interrogator/receiver (1) common RF unit generating (interrogation) (2) plurality of transmitter/receiver heads, each from, coupled to generator, or transponders its vicinity. Advantageously, head mixer performs four quadrant multiplication by produce third, audio frequency containing frequencies equal instantaneous difference between signals. One inputs transmission line connected transmit amplifier line; other input directional coupler that, turn, transmit/receive antenna. This operates pass line, amplifier, antenna mixer.