Transponder

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Transponder

In telecommunication

Telecommunication

Telecommunication is the assisted Transmission of Signal over a distance for the purpose of communication. In earlier times, this may have involved the use of smoke signals, Drum , Semaphore line, flag signals or heliograph....
, the term transponder (short-for Transmitter-responder and sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following meanings:

class="link1" onMouseover='showByLink("m36633",this)' onMouseout='hide("m36633")'href="http://www.absoluteastronomy.com/topics/Communications_satellite">communications satellite

Communications satellite

A communications satellite 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 and low Earth orbits....
’s channels

Channel (communications)

Channel, in communications , refers to the :wikt:medium used to information transfer information from a sender to a receiver ....
are called transponders, because each is a separate transceiver

Transceiver

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....
or repeater

Repeater

A repeater is an Electronics device that receives asignal and retransmits it at a higher level and/or higher power, or onto the other side of an obstruction, so that the signal can cover longer distances without degradation....
.

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Encyclopedia

In telecommunication

Telecommunication

An automatic
Automatic

Automatic may refer to:* Automatic transmission* Automatic firearm* Automatic watch*Automatic , a List of defunct United States automobile manufacturers United States automobile company...
device
Information appliance

An information appliance is an appliance specializing in information, a personal device designed to perform a specific activity, such as playing music, photography, or editing text, in a simple and user-friendly way....
that receives
Receiver (radio)

This article is about a radio receiver, for other uses see Radio .A radio receiver is an electronics circuit that receives its input from an antenna , uses electronic filters to separate a wanted radio signal from all other signals picked up by this antenna, electronic amplifier it to a level suitable for further processing, and finally...
, amplifies
Amplifier

Generally, an amplifier or simply amp, is any machine that changes, usually increases, the amplitude of a Signal . The "signal" is usually voltage or current....
, and retransmits
Transmission (telecommunications)

In telecommunications, transmission is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired or wireless....
a signal on a different frequency
Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency....
(see also broadcast translator).
An automatic device that transmits a predetermined message
Message

A message in its most general meaning is an Object of communication. It is something which provides information; it can also be this information itself....
in response
Response

A response is the following:* Often a response is the result of a stimulus.* In data transmission, a response is the content of the control field of a response frame advising the primary station concerning the processing by the secondary station of one or more command frames....
to a predefined received signal.
A receiver-transmitter
Transceiver

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....
that will generate a reply signal upon proper electronic
Electronics

Electronics refers to the flow of charge through nonmetal electrical conductor , whereas electrical refers to the flow of charge through metal electrical conductor....
interrogation
Interrogation

Interrogation or questioning is interviewing as commonly employed by officers of the police and military.The interviewee is also referred to as a "source"....
.

Satellite communications

A communications satellite

Communications satellite

Channel (communications)

Transceiver

Repeater

Digital video

Digital video is a type of video recording system that works by using a digital rather than an analog signal video signal.The terms camera, video camera, and camcorder are used interchangeably in this article....
data compression

Data compression

In computer science and information theory, data compression or source coding is the process of encoding information using fewer bits than an code representation would use through use of specific encoding schemes....
and multiplexing

Multiplexing

In telecommunications and computer networks, multiplexing is a process where multiple analog message signals or digital data streams are combined into one signal over a shared medium....
, several video

Video

Video is the technology of electronics Videography, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing Scene in motion....
and audio channels may travel through a single transponder on a single wideband

Wideband

In Telecommunication, wideband is a relative term used to describe a wide range of frequencies in a spectrum. A system is typically described as wideband if the message bandwidth significantly exceeds the channel's coherence bandwidth....
carrier

Carrier wave

In telecommunications, a carrier wave, or carrier is a waveform that is Modulation with an signal for the purpose of conveying information....
. Original analog video only has one channel per transponder, with subcarrier

Subcarrier

A subcarrier is a separate analog or digital signal carried on a main radio transmission , which carries extra information such as voice or data....
s for audio and automatic transmission identification service ATIS

ATIS

ATIS or Atis may refer to:*American Transportation Insurance Services Professional insurance for professional bus companies.*Automatic Terminal Information Service at airports...
. Non-multiplexed radio station

Radio station

This article is about radio broadcasting, for other uses see Radio .Radio broadcasting is an audio broadcasting service, traditionally broadcast through the air as radio waves from a transmitter to an antenna and a thus to a receiving device....
s can also travel in single channel per carrier

Single channel per carrier

Single channel per carrier refers to using a single Signalling at a given frequency and Bandwidth . Most often, this is used on broadcast satellites to indicate that radio stations are not multiplexing as subcarriers onto a single video carrier wave, but instead independently share a transponder....
(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 landline

Landline

A landline, main line or fixed-line is a telephone line which travels through a solid medium, either metal wire or optical fibre. This is distinguished from a mobile phone, where the medium used is the radio waves....
s to send it to an earth station for multiplexing with other stations.

Aviation

Another type of transponder occurs in identification friend or foe

Identification friend or foe

In telecommunications, identification, friend or foe is a cryptographic identification system designed for command and control. It is a system that enables military, and national interrogation systems to distinguish friendly aircraft, vehicles, or forces, and to determine their bearing and range from the interrogator....
systems in military aviation and in air traffic control

Air traffic control

Air traffic control is a service provided by ground-based Air traffic controller who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other support for pilots when able....
secondary surveillance radar

Secondary surveillance radar

Secondary surveillance radar is a radar system used in air traffic control , which not only detects and measures the position of aircraft but also requests additional information from the aircraft itself such as its identity and altitude....
(beacon radar) systems for general aviation

General aviation

Commercial aviation

Commercial aviation is the part of civil aviation that involves operating aircraft for hire. In most countries, a flight may be operated for money only if it meets three criteria:...
. Primary radar

Radar

Radar is a system that uses electromagnetic radiation waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain....
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 avoiding overinterogation of the transponder (having many radars in busy areas) and to allow automatic collision avoidance. Mode S transponders 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

General aviation

General aviation is one of two categories of civil aviation. It refers to all flights other than military aviation and scheduled air transport flights, both private aviation and commercial 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 glider

Glider

Heavier-than-air unpowered aircraft do not need propulsion once airborne. Gliders, balloons and kites are unpowered aircraft.Gliders such as gliders, hang gliders and paragliders gain their initial flying speed from some launch mechanism, and then gain additional energy from gravity and from updrafts such as thermal currents....
s, the power requirements during long flights.

Marine

Navigational aids often have transponders called RACON

Racon

A Racon is a type of radar transponder commonly used to mark maritime navigational hazards. The word is an acronym for RAdar beaCON.When a racon receives a radar pulse, it responds with a signal on the same frequency which leaves an image on the radar display....
designed to make them standout on a ship's radar screen.

Automotive

Many modern automobiles (especially the more expensive models) have keys with transponders hidden inside the plastic head of the key. The owner of the car may not even be aware that the transponder is there because there are no buttons to press. When a key is inserted into the ignition lock cylinder and turned, the car's computer sends a radio signal to the transponder. Unless the transponder replies with a valid code, the computer will not allow the engine to be started. Transponder keys have no battery; they are energized by the radio signal itself.

Road

The E-ZPass

E-ZPass

E-ZPass is an electronic toll collection system used on most tolled roads, bridges, and tunnels in the northeastern United States. Currently, there are 24 agencies spread across 13 states that make up the ....
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.

Passive and active RFID systems are used in off road events such as Enduro

Enduro

Enduro is a form of motorcycle sport run on courses that are predominantly off-road. Enduro consists of many different obstacles and challenges....
and Hare and Hounds racing, the riders have a transponder on their person, normally on their arm. When they complete a lap they swipe or touch the receiver which is connected to a computer and log their lap time. The Casimo Group Ltd make a system which does this.

NASCAR

NASCAR

The National Association for Stock Car Auto Racing is the largest sanctioning body of stock cars in the United States. The three largest racing series sanctioned by NASCAR are the Sprint Cup Series, the Nationwide Series and the Camping World Truck Series....
uses transponders and cable loops placed at numerous points around the track to determine the lineup during a caution period. This system replaced a dangerous race back to the start-finish line

Racing back to the caution

In automobile racing, specifically NASCAR stock car racing, "racing back to the caution" is a term used to describe a procedure about what drivers did after a caution flag was displayed....
.

Underwater

Sonar

Sonar is a technique that uses sound propagation to navigation, communicate with or detect other vessels. There are two kinds of sonar: active and passive....
transponders operate under water and are used to measure distance and form the basis of underwater location marking, position tracking and navigation

Navigation

Navigation is the process of reading, and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks....
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Gated communities

Transponders may also be used by residents to enter their gated communities

Gated community

In its modern form, a gated community is a form of residential community containing controlled entrances for pedestrians, bicycles, and automobiles, and sometimes characterised by a closed perimeter of walls and fences....
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Transponder

Satellite communications

Aviation

Marine

Automotive

Road

Motorsport

Underwater

Gated communities

See also