Crossword clues for transponder
Longman Dictionary of Contemporary English
Douglas Harper's Etymology Dictionary
1945, from trans(mit) + (res)pond + agent noun suffix -er (1).
Wiktionary
n. A radio or radar transceiver that transmits some signal in response to receive a predetermined signal.
WordNet
n. electrical device designed to receive a specific signal and automatically transmit a specific reply
Wikipedia
In telecommunication, a transponder is one of two types of devices. In air navigation or radio frequency identification, a flight transponder is a device that emits an identifying signal in response to an interrogating received signal. In a communications satellite, a transponder gathers signals over a range of uplink frequencies and re-transmits them on a different set of downlink frequencies to receivers on Earth, often without changing the content of the received signal or signals.
The term is a portmanteau for transmitter-responder. It is variously abbreviated as XPDR, XPNDR, TPDR or TP.
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. Aircraft have transponders to assist in identifying them on air traffic control radar; and collision avoidance systems have been developed to use transponder transmissions as a means of detecting aircraft at risk of colliding with each other.
Air traffic control units use the term "squawk" when they are assigning an aircraft a transponder code, e.g., "Squawk 7421". Squawk thus can be said to mean "select transponder code" or "squawking" to mean "I have selected transponder code xxxx".
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 communication to transfer the received signals.
A transponder is typically composed of:
- An input band limiting device (a band pass filter)
- An input low-noise amplifier (LNA), designed to amplify the (normally very weak, because of the large distances involved) signals received from the earth station
- A frequency translator (normally composed of an oscillator and a frequency mixer) used to convert the frequency of the received signal to the frequency required for the transmitted signal
- An output band pass filter
- A power amplifier (this can be a traveling-wave tube or a solid state amplifier)
Most communication satellites are radio relay stations in orbit, and carry dozens of transponders, each with a bandwidth of tens of megahertz. Most transponders operate on a principle, sending back to earth of what goes into the conduit with only amplification and a shift from uplink to downlink frequency. However, some modern satellites use on-board processing, where the signal is demodulated, decoded, re-encoded and modulated aboard the satellite. This type, called a "regenerative" transponder, has many advantages, but is much more complex.
With data compression and multiplexing, several video (including digital video) and audio channels may travel through a single transponder on a single wideband carrier.
Original analog video only had 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.
NASA distinguishes between a "transponder" and a " transceiver", where the latter is simply an independent transmitter and receiver packaged in the same unit, and the former derives the transmit carrier frequency from the received signal. This linkage allows an interrogating ground station to recover the Doppler and thus infer range and speed from a communication signal without allocating power to a separate ranging signal.
Usage examples of "transponder".
Earlier, NSA had succeeded in intercepting a weak beacon transponder signal transmitted from a small spiral antenna on the tail of the Soviet SA-2 surface-to-air missile.
There were pea-sized transponders buried every thousand meters of the winding route between where Luna was being built and the Waterworks, which was up nearer to the north pole.
He ran into a north-south transponder road, and followed it up a short rise to the southern rim of Melas Chasma, and got out of the rover to have a proper look.
Whatever they transmitted would go to transponder 21 on the satellite, then instantly by downlink to New York to be rerecorded.
Half the pirates and three-quarters of the privateers roaming Silesian space were probably running on faked transponder IDs.
Comsat kept track of Cerberus personnel when they were away from the redoubt through telemetric signals relayed by subcutaneous transponders.
The transponder beeped softly, lights flickering briefly in the heads-up display, and Cerise gave a sigh of relief.
However, while the forcefield is able to keep out the relatively passive signals generated by bioreadings and combadges, it cannot deter the more active signals of the artifact or the transponder.
Robinette came up on the assigned frequency, contacted Baghdad, and switched her commercial IFF transponder to the assigned squawk.
And, as Komulakov had planned, the GPS transponder in the little encryption device provided the exact location of the QRF every time Coombs communicated.
Their radars are set up to receive coded signals from aircraft transponders, not pick up skin paints.
Not only had the ulation risen by almost fifty percent, but more military skimmers reduced its traffic patterns to they cut across them, their shrill transponder raring a path through the carefully-nurtured ore air traffic authorities, the Peaceforce skimmer ng Government House was only one more flaw beaw puzzle of their job.
But if Cabell had discovered how it worked, the source of its power remained a mystery-one he hoped to solve by analyzing the transponder.
The color change flowed through the formation in a cascade, one LAC squadron at a time as each of them brought its transponders online.
However, in this day and age an equal priority went to its shorter neighbour, a two-way transponder for amplifying and relaying mobile phone service signals.