transponder(redirected from Mode C)
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A radio or radar transmitter-receiver activated for transmission by reception of a predetermined signal.
[tran(smitter) + (re)sponder.]
1. (Telecommunications) a type of radio or radar transmitter-receiver that transmits signals automatically when it receives predetermined signals
2. (Broadcasting) the receiver and transmitter in a communications or broadcast satellite, relaying received signals back to earth
[C20: from transmitter + responder]
a radio, radar, or sonar transceiver that automatically transmits a signal upon reception of a designated incoming signal.
A receiver-transmitter which will generate a reply signal, upon proper interrogation. See also responsor.