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Transponder: Difference between revisions
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Transponders are radio beacons which make aircraft more identifiable on ATC displays and systems. Modern transponders support transmitting additional data such as an identification ('squawk') code and aircraft altitude. See more at [http://en.wikipedia.org/wiki/Transponder_(aviation) Transponder](Wikipedia) | '''Transponders''' are radio beacons which make [[aircraft]] more identifiable on [[ATC]] displays and systems. Modern transponders support transmitting additional data such as an identification ('squawk') code and aircraft altitude. See more at [http://en.wikipedia.org/wiki/Transponder_(aviation) Transponder] (Wikipedia). | ||
== Id Codes == | == Id Codes == | ||
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== Modes == | == Modes == | ||
See [http://en.wikipedia.org/wiki/Aviation_transponder_interrogation_modes Aviation transponder interrogation modes](Wikipedia) for official description. Civilian Mode-S and Mode-C both transmit pressure altitude (at 10-foot and 100-foot precision, respectively). To do this the transponder needs an altitude source. In real-life this can be a separate box called an encoder, or may be derived for FMC / ADIRU sources. It's important to note this altitude is referenced to standard pressure (29.92 inHg / 1012Hpa), and not corrected for actual barometric pressure in the local environment. | See [http://en.wikipedia.org/wiki/Aviation_transponder_interrogation_modes Aviation transponder interrogation modes] (Wikipedia) for official description. Civilian Mode-S and Mode-C both transmit pressure altitude (at 10-foot and 100-foot precision, respectively). To do this the transponder needs an altitude source. In real-life this can be a separate box called an encoder, or may be derived for FMC / ADIRU sources. It's important to note this altitude is referenced to standard pressure (29.92 inHg / 1012Hpa), and not corrected for actual barometric pressure in the local environment. | ||
Additional support for military modes is possible if anyone wishes to add it. | Additional support for military modes is possible if anyone wishes to add it. | ||
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The default altimeter can act as an altitude encoder; in its configuration, set either or both of the following boolean flags: | The default altimeter can act as an altitude encoder; in its configuration, set either or both of the following boolean flags: | ||
* encode-mode-c | |||
* encode-mode-s | |||
The transponder has various config properties: | The transponder has various config properties: | ||
* bus-volts : required DV volts for operations, defaults to 8.0 | * '''bus-volts''': required DV volts for operations, defaults to 8.0 | ||
* encoder-path | * '''encoder-path''': defaults to '/instruments/altimeter', but can be changed to any other location. The transponder looks for child properties 'mode-c-alt-ft' and 'mode-s-alt-ft' at this path for altitude data. | ||
* kt70-compatability | * '''kt70-compatability''': boolean, default to false. Set this to enable legacy compatibility with the old KT-70 C++ instrument. Do not use in new/updated aircraft! | ||
* mode | * '''mode''': this is 0 for Mode-A, 1 for Mode-C and 2 for Mode-S. Other modes can be added, ask on the [[Mailing list|devel list]]! | ||
=== Run-time properties === | === Run-time properties === | ||
* id-code allows the id-code to be read and set | * '''altitude''': gives the transmitted altitude in feet (or -9999 for invalid) | ||
* transmitted-id gives the value being transmitted, including over the network via MP | * '''altitude-valid''': indicates if altitude value is valid data or not | ||
* '''id-code''': allows the id-code to be read and set | |||
* '''serviceable''': can be set to control the instrument serviceability | |||
* '''transmitted-id''': gives the value being transmitted, including over the network via MP | |||
====Input properties | ====Input properties==== | ||
These live under <tt>/inputs</tt>. | |||
* knob-mode sets the transponder operating mode. This corresponds to the KT-70 knob positions for convenience, but the actual modes should work for any transponder instrument. Knob modes are documented below | * '''knob-mode''': sets the transponder operating mode. This corresponds to the KT-70 knob positions for convenience, but the actual modes should work for any transponder instrument. Knob modes are documented below | ||
* ident-button can be set to place the transponder in ident mode for 18 seconds. Note this property is not spring-loaded, i.e you must manually reset it to false | * '''ident-button''': can be set to place the transponder in ident mode for 18 seconds. Note this property is not spring-loaded, i.e you must manually reset it to false | ||
* digit[0]-[4] properties allow the id code individual digits to be read and set | * '''digit[0]-[4]''': properties allow the id code individual digits to be read and set | ||
In KT-70 compatibility mode, additional properties are read and set, to preserve legacy aircraft. Do not use these properties in new aircraft. | In KT-70 compatibility mode, additional properties are read and set, to preserve legacy aircraft. Do not use these properties in new aircraft. | ||
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* 4 - On, normal operation but altitude transmission is inhibited | * 4 - On, normal operation but altitude transmission is inhibited | ||
* 5 - Alt, same as on but altitude is broadcast if transponder was configured in Mode-S or Mode-C | * 5 - Alt, same as on but altitude is broadcast if transponder was configured in Mode-S or Mode-C | ||
[[Category:Aircraft enhancement]] | |||
[[Category:Aircraft instruments]] | |||