A transducer is a device, USUALLY electrical, electronic, electro­mechanical, electromagnetic, PHOTONIC, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.

In telecommunication, the TERM transponder (shortforTransmitter­responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:

1. An automatic device that receives, amplifies, andretransmits a signal on a different frequency (see alsobroadcast TRANSLATOR).
2. An automatic device that transmits a predetermined messagein response to a predefined received signal.
3. A receiver­transmitter that will generate a reply signal upon proper electronic interrogation.
4. A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater.

A transducer is a device, usually electrical, electronic, electro­mechanical, electromagnetic, photonic, or photovoltaic that converts one type of energy or physical attribute to another for various purposes including measurement or information transfer.

In telecommunication, the term transponder (shortforTransmitter­responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings: