Information AboutTransponder |
| CATEGORIES ABOUT TRANSPONDER | |
| avionics | |
| communication circuits | |
| radio electronics | |
| radar | |
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In Telecommunication , the term transponder (short-for ''Trans''mitter-res''ponder'' and sometimes abbreviated to XPDR, XPNDR or TPDR) has the following meanings:
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 Subcarrier s for audio and automatic transmission identification service ATIS . Non-multiplexed Radio Station s 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 Landline s to send it to an Earth Station for multiplexing with other stations. 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 curcuit near to the start/finish line. Each car has an active transponder with an 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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