1945, from trans(mit) + (res)pond + agent noun suffix -er (1).

An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with "pa [..]

Transmitter-receiver device on a satellite that transmits signals automatically when it receives predetermined signals. The term “satellite transponder” refers collectively to a transmitter-receiver s [..]

Satellite receiver/transmitter unit receives uplink signals, which it amplifies and retransmits as a downlink signal back to earth.

An electronic device aboard the airplane that enhances an aircraft's identity on an ATC radar screen.

An automatic device that receives, amplifies, and retransmits a signal on a different frequency. 2. An automatic device that transmits a predetermined message in response to a predefined received signal. Note: An example of transponders is in identification-friend-or-foe systems and air-traffic-control secondary radar (beacon radar) systems. 3. A r [..]

An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with "pa [..]

Communications device that sends out signal allowing air traffic controllers to track an airplane. Transponders were disabled in some of the planes hijacked Sept. 11. President Bush has proposed requiring transponders that cannot be disabled from the aircraft.

A wireless communications device usually attached to a satellite. A transponder receives and transmits radio signals at a prescribed frequency range. After receiving the signal a transponder will at t [..]

The device in a satellite that receives, ‘processes’ and re-transmits the signal from/to Earth.

An acoustic device that scientists place above the seafloor, usually in groups of two or more, to help them navigate deep submergence vehicles. To locate a transponder, a ping is broadcast from a ship to the seafloor. If the transponder hears the ping, it sends a reply ping, letting researchers know they’re in the right place. The transponder and i [..]

An electronic device that "responds" to interrogation by ground-based radar with a special four-digit code that specifically identifies the aircraft on which it is located. Certai [..]

Satellite transmitter and receiver that receives and amplifies a signal prior to retransmission to an earth station.

A wireless communications device that detects and responds to an RF signal.

A receiver that transmits signals when activated by a specific signal. For example, a satellite transponder picks up signals from the earth, translates them into a new frequency, amplifies them, and t [..]

transponder is the portion of a communications satellite that acts as a receiver, amplifier, and retransmitter for the signals communicated up to and down from the satellite.

The in-vehicle device component of a dedicated short-range corporation (DSRC) (or ETC) system. A receiver or transceiver permits the Operator's Road-Side Unit to communicate with, identify, and conduct an electronic toll transaction. Also call On-Board Unit and Tag.

(n) electrical device designed to receive a specific signal and automatically transmit a specific reply

an acoustic signaling device that automatically transmits a sonar signal upon reception of a designated incoming signal. Transponders are used to mark or track underwater objects.

Airborne receiver/transmitter portion of the SSR

An electronic device that "responds" to interrogation by ground-based radar with a special four-digit code that specifically identifies the aircraft on which it is located. Certain transponders have the ability to transmit automatically the altitude of the aircraft in addition to the special code.

A cockpit receiver/transmitter that receives signals from ground-based radar and transmits a specific code back to the ground-based equipment. This allows air traffic controllers to identify specific [..]

A transponder is a piece of avionics that replies to a radar signal with a short identifier and (if it knows it) the altitude of the aircraft. This information makes ATC's life easier, which m [..]

An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with "pa [..]

In SCOOT bus priority, transponders can be fitted to buses so that when a bus travels over a bus detector on-street or goes past a beacon SCOOT knows that a bus is approaching a signal. SCOOT can also take information from AVL systems.

a device aboard the aircraft that will reply to a ground-based probe signal. This reply makes the aircraft more visible on a controller's radar screen. The signal transmitted by a transponder is [..]

An electronic device on board aircraft which sends out coded information which is picked up by radar and other systems. Most importantly the aircraft altitude, and identity code, by which the aircraft can be identified on the radar screen.

An electronic tag attached to a vehicle and scanned by a roadside device that identifies the vehicle and takes appropriate action (e.g., charge a toll).

Device that adheres to the inside of a vehicle's windshield and allows hands-free access to authorized gated facilities.

Batteryless electronic code memory which transmits and receives low frequency messages upon activation by an external electromagnetic field.

Equipment in a satellite which receives a single uplinked channel from a satellite earth station; amplifies it, converts the frequency and changes the polarisation; then transmits it back to the Earth in a given power (EIRP).

Is the equivalent to a satellite channel. The satellite receives, amplifies, and transmits a signal back to earth on various transponders.

A satellite’s own receiver and transmitter.

Electronic device which combines a transmitter and a receiver.

Satellite receiver/transmitter unit receives uplink signals, which it amplifies and retransmits as a downlink signal back to earth.

An electronic device that responds to interrogation by ground-based radar with a special four-digit code that air traffic control specifically assigns to the aircraft on which it is located. Certain transponders have the ability to transmit automatically the altitude of the aircraft in addition to the special code.

The term transponder is a combination of the words transmitter and responder. Transponders usually consist of an antenna and a microchip. There are active transponders that have their own power supply in the form of batteries. With passive transponders, the energy field of a relevant reading device provides the power supply. They are seen as promis [..]

A transponder is an on-board equipment with a dedicated short-range communication (DSRC) interface and a buzzer as the only human-machine interface to the driver

See xpdr

The transmitter that sends automatic coded ID info to radar operators. See "IFF" and "Squawk".

See xpdr

An airborne transmitter that responds to ground-based interrogation signals to provide air traffic controllers with more accurate and reliable position information than would be possible with “passive” radar; may also provide air traffic control with an aircraft’s altitude.

A portmanteau of transmitter-responder, the transponder emits a radio signal based on an interrogation from an outside source, either air traffic control or another aircraft.

A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation. In aviation, aircraft have transponders to assist in identifying them on radar and on o [..]

An airborne electronic device which automatically responds to querying pulses in synchrony with ground radar.  All transponders transmit an assigned ("squawk") code, which identifies the airplane to radar controllers. Only 'Mode C' (altitude encoding) transponders provide a measurement of the aircraft's altitude MSL. Both a [..]

An airborne device that transmits an identifying signal that responds to ground-based interrogation signals. A transponder can also provide an aircraft’s altitude to Air Traffic Control.

A device that transmits a response signal automatically when activated by an incoming signal.

Airborne receiver/transmitter portion of the SSR system which receives the interrogation signal from the ground and automatically replies according to mode and code selected. Modes A and B are used fo [..]

An automatic device that transmits a predetermined message in response to a predefined received signal.

An electronic tag installed in a vehicle for electronic road pricing. The tag is read electronically by an electronic tolling device that automatically assesses the amount of the user fee.

An automatic device that receives, amplifies, and retransmits a signal on a different frequency.

A radio or radar transceiver that transmits some signal in response to receiving a predetermined signal.

In telecommunication, a transponder can be one of two types of devices. In air navigation or radio frequency identification, a flight transponder is an automated transceiver in an aircraft that emits [..]

In telecommunication, a transponder can be one of two types of devices. In air navigation or radio frequency identification, a flight transponder is an automated transceiver in an aircraft that emits [..]

A transponder (short for transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) is an electronic device that produces a response when it receives a radio-frequency interrogation. [..]

A communications satellite's transponder is the series of interconnected units that form a communications channel between the receiving and the transmitting antennas. It is mainly used in satellite [..]