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I'm dealing with recorded ADS-B data as a part of my thesis (programming-oriented).

I have a table of ADS-B communication of an aircraft (image below) - I know, that some of these recorded data in the table come from Mode S and some from ADS-B system itself. I need to know which of these data (GPS coordinates, heading, TAS, Mach and meteo data) come from the Mode S and which come from ADS-B (or FIS-B).

I'm unable to find any source, that would distinguish between data sources of these data.

recorded ADS-B data

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2 Answers 2

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All the recorded transmissions you have, seem to come from the same aircraft. They come all from the onboard (Mode-S) transponder.

All transmission with Downlink Format (DF) 17 are ADS-B. Those with DF18 are TIS-B (or ADS-R), you don't have any of these (they are rare in Europe, and more common in the US)

Mode-S uses the following DF's:

  • DF4 - altitude reply (short)
  • DF5 - identiy reply (short)
  • DF11 - all call reply / Mode S squitter
  • DF20 - Comm. B / altitude reply (long)
  • DF21 - Comm. B / identity reply (long)
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  • $\begingroup$ Thanks. Yes, this is one aircraft only. So none of these data come from direct SSR Mode S addressed communication but from ADS-B only? I just want to be sure, I am not even sure, if its possible to record direct radar-transponder communication with ads-b receiver. $\endgroup$
    – Václav
    Commented Jun 17, 2019 at 17:23
  • $\begingroup$ Only those with DF=17 are from ADS-B. The DF20 and DF21 in your table are Mode-S replies. It's perfectly possible to record direct transponder>radar communication with an ADS-B receiver. I've done so for a living (and still do sometimes). $\endgroup$
    – DeltaLima
    Commented Jun 17, 2019 at 17:27
  • $\begingroup$ Okey, thank you very much. I understand it now. TIS-B/FIS-B ground systems are not available in Europe (afaik, if you know about some, tell me please :-) ). One more thing (sorry to bother you) - what is the possible source of meteorological data (as in table above) in ads-b communication? FIS-B only? Or is there some alternative like adding it later? $\endgroup$
    – Václav
    Commented Jun 17, 2019 at 17:34
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    $\begingroup$ Meteorological data is not available in the current version ADS-B (ED-102A / DO-260B) but is planned for the next version. $\endgroup$
    – DeltaLima
    Commented Jun 17, 2019 at 18:47
  • $\begingroup$ Okey, thank you very much :-) $\endgroup$
    – Václav
    Commented Jun 18, 2019 at 13:54
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ADS-B has two defined datalinks, 1090ES and UAT978.

UAT978 is, so far, only available in the US.

FIS-B is weather radar and similar data, and is only available on UAT978.

1090ES datalink is an enhancement to Mode S that adds DF17 messages with position, velocity and other ADS-B data.

TIS-B is a ground-based service that transmits ADS-B-like messages on behalf of radar targets that do not send their own. In the case of 1090ES, it uses DF18.

ADS-R is another ground based service that relays ADS-B messages on one datalink to another. Since the only country with two datalinks today is the US, that's the only place you'll see ADS-R messages. For 1090ES, it also uses DF18. It can be distinguished from TIS-B by the address type field.

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  • $\begingroup$ Thank you. What is the DF code for FIS-B messages, please? $\endgroup$
    – Václav
    Commented Jun 17, 2019 at 18:03
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    $\begingroup$ @Václav There is no FIS-B on 1090 MHz, so no DF for FIS-B $\endgroup$
    – DeltaLima
    Commented Jun 17, 2019 at 18:48
  • $\begingroup$ Okey, thank you very much :-) $\endgroup$
    – Václav
    Commented Jun 18, 2019 at 13:54

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