TRANSPONDER
Pilot/Controller Glossary with JO 7110.65BB, Change 3, effective July 9, 2026 · Official text on faa.gov
The airborne radar beacon receiver/transmitter portion of the Air Traffic Control Radar Beacon System (ATCRBS) which automatically receives radio signals from interrogators on the ground, and selectively replies with a specific reply pulse or pulse group only to those interrogations being received on the mode to which it is set to respond.
See INTERROGATOR; TRANSPONDER ICAO.
Refer to AIM.
ICAO definition
A receiver/transmitter which will generate a reply signal upon proper interrogation; the interrogation and reply being on different frequencies.