transponder
n. countablen. a piece of equipment that receives a radio signal and automatically sends a different signal back. You find these on planes and ships so that radar can identify them.
n. an electronic device that emits a response upon receiving a specific radio-frequency interrogation signal. Commonly used in aviation and maritime contexts for identification and tracking.
The pilot turned on the transponder before takeoff.
Air traffic control lost the aircraft's position on the screen after its transponder stopped transmitting.
Modern satellite communications rely on multiple transponders to receive signals from Earth and retransmit them across a broad geographic area on different frequencies to avoid interference.
Blend of transmitter + responder.
Often used in technical contexts involving telecommunications, aviation, or satellite technology.