Transducer and Transponder
A transducer is a device, typically electrical, electronic, electromechanical, electromagnetic, photonic, or photovoltaic, designed to convert one form of energy or physical attribute into another for various purposes, including measurement or information transfer.
In the field of telecommunication, the term “transponder,” often shortened to “XPDR,” “XPNDR,” “TPDR,” or “TP,” holds several meanings:
- It can refer to an automatic device that receives an incoming signal, amplifies it, and then retransmits it on a different frequency. This is similar to what a broadcast translator does in some cases.
- It can also denote an automatic device that, upon receiving a specific pre-defined signal, transmits a predetermined message in response.
- In the context of electronic interrogation, a transponder is a receiver transmitter that generates a reply signal when properly interrogated or prompted electronically.
- In the realm of communications satellites, the term “transponders” is used because each channel on the satellite functions as a separate transceiver or repeater, facilitating the relay of signals between Earth-based communication devices.