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I searched the placement of ASTERIX Category 240 radar video data fields in a UDP packet. But I cannot find any useful info. Is there a standard for this work?

bogl
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doner_t
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    I don't think the Aviation section of the Stack Exchange is the appropriate section to ask this question. – Skip Miller Jun 08 '19 at 15:20
  • @SkipMiller I think it fits. Not possible for me to answer it from mobile phone now, but I am happy to take it later. – DeltaLima Jun 08 '19 at 16:27

2 Answers2

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The Asterix structure is explained in detail on this document on the Eurocontrol site.

Wireshark.org has a page explaining the protocol as well.

GdD
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  • Thank you @GdD. Will I be able to decide whether the received packets are in CAT 240 protocol? You mean that I can decode & analyze & seen all necessary fields of CAT 240 by using Wireshark? I have downloaded and opened the sample pcap given page you shared. In which ASTERIX category are these UDP packets encoded? Is there a method? I want to say "Yes, this UDP packets in the Wireshark are ASTERIX Category 240 or Cat ..etc" – doner_t Jun 09 '19 at 09:49
  • Wireshark should be able to tell you if it's cat 240, that's just a field in a fixed length packet, so even if the wireshark decoder doesn't say exactly which category it is you could figure it out yourself using wireshark's built in tools. – GdD Jun 09 '19 at 10:02
  • Correct. I got it. For instance, shared Wireshark pcap sample are seen cat 048 and cat 034. – doner_t Jun 09 '19 at 10:11
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It has been some time since this question was asked, but I still decided to answer it. Usually, ASTERIX messages are sent in UDP packets, but there is no dedicated standard port for that kind of messages. Sometimes, you can find information that that port should be 8600, but nobody really uses it.

Therefore, when you open ASTERIX recording, you see just raw data like this.

enter image description here

You have to setup Wireshark to decode ASTERIX data. Since data is usually sent to some predefined ports, you tell Wireshark to decode that data as ASTERIX. Go to Analyze -> Decode As..., and setup the UDP ports, where ASTERIX data is like this:

enter image description here

After you configure Wireshark, you can see decoded ASTERIX data.

enter image description here

However, ASTERIX Category 240 is not supported in Wireshark yet. Please, send me some sample data of Category 240, and I can add it to Wireshark.

nobody
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  • Please see an example capture from Wireshark here for ASTERIX Category 240. https://drive.google.com/file/d/1D0IbSXZxQPXhK8mcVdZiO1NH4PzCDTDV/view?usp=sharing – Bernad Peter Oct 21 '21 at 05:51
  • @Bernard Peter I am not maintaining the ASTERIX dissector in Wireshark directly any more. Right now a new version of dissector has been submitted to Wireshark, which generates the code from ASTERIX specifications. Therefore, the decoding is not coded directly into source code any more, but the ASTERIX spec has to be entered, and from there the new code will be generated. Take a look here https://zoranbosnjak.github.io/asterix-specs/index.html, hos specs are defined, and contact an email published on "SOURCE" subpage to get specs for CAT240. – nobody Oct 28 '21 at 12:40