TRANSPONDER

1 . An automatic device that receives, amplifies, and retransmits a signal on a different frequency . ( 188 ) 2. An automatic device that transmits a predetermined message in response to a predefined received signal. ( 188 ) Note: An example of transponders is in identification-friend-or-foe systems and air-traffic-control secondary radar (beacon radar) systems. 3. A receiver-transmitter that will generate a reply signal upon proper interrogation . [ JP1 ]