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Information about Transponders

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A Highway 407 toll transponder
In telecommunication, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR, XPNDR or TPDR) has the following meanings:

Satellite communications

For more details on this topic, see Transponder (Satellite communications).
A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater. With digital video data compression and multiplexing, several video and audio channels may travel through a single transponder on a single wideband carrier. Original analog video only has one channel per transponder, with subcarriers for audio and automatic transmission identification service ATIS. Non-multiplexed radio stations can also travel in single channel per carrier (SCPC) mode, with multiple carriers (analog or digital) per transponder. This allows each station to transmit directly to the satellite, rather than paying for a whole transponder, or using landlines to send it to an earth station for multiplexing with other stations.

Aviation

For more details on this topic, see Transponder (aviation).


Another type of transponder occurs in identification friend or foe systems in military aviation and in air traffic control secondary surveillance radar (beacon radar) systems for general aviation and commercial aviation. Primary radar works best with large all-metal aircraft, but not so well on small, composite aircraft. Its range is also limited by terrain and rain or snow and also detects unwanted objects such as automobiles, hills and trees. Furthermore it cannot estimate the altitude of an aircraft. Secondary radar overcomes these limitations but it depends on a transponder in the aircraft to respond to interrogations from the ground station to make the plane more visible.

Depending on the type of interrogation, the transponder sends back a transponder code (or "squawk code") (Mode A) or altitude information (Mode C) to help air traffic controllers to identify the aircraft and to maintain separation. Another mode called Mode S (Mode Select) is designed to help air traffic control in busy areas and allow automatic collision avoidance. Mode S tranponders are 'backwards compatible' with Modes A & C. Mode S is mandatory in controlled airspace in many countries. Some countries have also required, or are moving towards requiring, that all aircraft be equipped with Mode S, even in uncontrolled airspace. However in the field of general aviation, there have been objections to these moves, because of the cost, size, limited benefit to the users in uncontrolled airspace, and, in the case of balloons and gliders, the power requirements during long flights.

Marine

Navigational aids often have transponders called RACON designed to make them standout on a ships radar screen.

Road

The E-ZPass system in the eastern United States is one of many systems for paying bridge and road tolls by a RFID transponder in the car.

Motorsport

Transponders are used in motorsport for lap timing purposes. A cable loop is dug into the race circuit near to the start/finish line. Each car has an active transponder with a unique id code. When the racing car passes the start/finish line the lap time and the racing position is shown on the score board.

Underwater

Sonar transponders operate under water and are used to measure distance and form the basis of underwater location marking, position tracking and navigation.

See also

Source: partly from Federal Standard 1037C and from MIL-STD-188 and from the Department of Defense Dictionary of Military and Associated Terms
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amplifier is any device that will use a small amount of energy and convert it to a larger amount of energy. In popular use, the term today usually refers to an electronic amplifier, often as in audio applications.
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  • Usually a response is a reply to a query.
  • In data transmission, a response is the content of the control field of a response frame advising the primary station concerning the processing by

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A transceiver is a device that has both a transmitter and a receiver which are combined and share common circuitry or a single housing. If no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s.
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Interrogation is a methodology employed during the interview of a person, referred to as a "source", to obtain information that the source would not otherwise willingly disclose.
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A communications satellite’s channels are called transponders, because each is a separate transceiver or repeater. With digital video data compression and multiplexing, several video and audio channels may travel through a single transponder on a single wideband carrier.
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communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the purposes of telecommunications. Modern communications satellites use a variety of orbits including geostationary orbits, Molniya orbits, other elliptical orbits
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Channel, in communications (sometimes called communications channel), refers to the used to convey information from a sender (or transmitter) to a receiver.

Overview

A Channel can take many forms.
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A transceiver is a device that has both a transmitter and a receiver which are combined and share common circuitry or a single housing. If no circuitry is common between transmit and receive functions, the device is a transmitter-receiver. The term originated in the early 1920s.
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Theory — boolean logic | digital signal processing | computer architecture
Applications — digital photography | digital audio | digital video
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data compression or source coding is the process of encoding information using fewer bits (or other information-bearing units) than an un-encoded representation would use through use of specific encoding schemes.
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The two main classes of sound recording technology are analog recording and digital recording.
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For the automotive term, see .


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ATIS or Atis may refer to:
  • Adventure Thru Inner Space
  • Automatic Terminal Information Service (Airport)
  • Alliance for Telecommunications Industry Solutions
  • Association of Translators and Interpreters of Saskatchewan

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worldwide view of the subject.
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Radio broadcasting is an audio (sound) broadcasting service, traditionally broadcast through the air as radio waves (a form of electromagnetic radiation) from a
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