also: トランスポンダ
transponder
A device that receives a radio signal and automatically transmits a reply; used in aviation, telecommunications, and satellite systems.
Aircraft are equipped with transponders.
The radar site received a signal from the transponder.
This aircraft is equipped with the latest transponder.
The transponder responded to the signal from the radar.
Borrowed from English 'transponder', a blend of 'transmitter' and 'responder'.