transponder
/trænsˈpɑndər/
noun
- An electronic device that receives a signal and automatically transmits a reply, used in communication, navigation, and identification systems.
- The airplane's transponder sends a signal to air traffic control so they can track its location.
- Each car in the race has a transponder that records its time as it crosses the finish line.
- The satellite's transponder relays television signals from the broadcaster to homes around the world.
- A device on a vehicle or vessel that responds to a radar or sonar signal, used for identification and tracking.
- Hikers in remote areas carry a personal transponder that can send an emergency signal if they get lost.
- The submarine activated its transponder to confirm its position to the naval base.
- The ship's transponder allows coast guard radar to identify it even in fog.