transponder

American  

[tran-spon-der] / trænˈspɒn dər /

Or transpondor

noun

1. a radio, radar, or sonar transceiver that automatically transmits a signal upon reception of a designated incoming signal.

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transponder British  

/ trænˈspɒndə /

noun

1. a type of radio or radar transmitter-receiver that transmits signals automatically when it receives predetermined signals

2. the receiver and transmitter in a communications or broadcast satellite, relaying received signals back to earth

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transponder Scientific  

/ trăn-spŏn′dər /

1. A radio or radar transmitter and receiver that responds to an incoming signal either by broadcasting its own predetermined signal (as in aircraft identification systems) or by relaying the incoming signal at a different frequency (as in satellite communications).

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Etymology

Origin of transponder

First recorded in 1940–45; trans(mitter) + (res)ponder

Example Sentences

A "dark" vessel -- usually a tanker or cargo carrier -- deliberately disables or manipulates transponders in a bid to go undetected by public tracking systems like Kpler's MarineTraffic.

From Barron's

Russian and Iranian ships would often turn off their transponders while making their runs, leaving them even harder to track, analysts said.

From The Wall Street Journal

Homendy added that the runway safety system ASDE-X, designed to track aircraft and ground vehicles, did not generate an alert before the crash because the fire truck was not equipped with a transponder.

From Barron's

Tracking site MarineTraffic said the Karachi transited the strait with its automatic transponder system activated -- where most vessels keep it turned off to avoid being targeted.

From Barron's

A Pakistani oil tanker transited the Strait of Hormuz with its automatic transponder system activated, monitor Marine Traffic said, the first such voyage by a non-Iranian tanker since the start of the war.

From Barron's