Observation 3377133: AISTECHSAT-2 (43768)

Quite a few packets this pass. Looking at the ASCII decodes I see what looks to be aircraft ADS-B messages with callsigns/flight number. Haven’t taken the time to try and run it through some ADS-B decoder software to see if it’s a verbatim repeat of the received ADS-B data.

Aside: How can that be true, the post above was 29 Dec 2020; it’s still Jan 2021 now?

Anyway, I had a play and came up with this starting point of a Kaitai struct for messages containing flight number text. e.g. data_3561356_2021-01-30T05-15-04 from Observation 3561356 contains reference to VIV3185 which was flown by XA-VAW which has ICAO ID 0x0D0A77. Until I matched that it seemed odd to have a CRLF 0x0D0A sequence in there.

I don’t think it’s direct ADS-B format. There must be some processing going on as the callsign is encoded into 6-bit text, so wouldn’t appear in plain. Lots of detail at The 1090MHz Riddle. There’s likely latitude, longitude and altitude information in there, but the encoding is horrendous so it’s a bit of a guess to work out what’s been processed and what hasn’t without known ground truth to compare against.