If you are into reverse engineering, the EU Galileo navigation satellites are currently transmitting a new signal that enables centimeter level accurate positioning. But! They haven't yet released a description of this format, but the data is there & unencrypted. 1/2
Let me know if you want a dump of many hours of data. The data likely includes a distance vector that describes a correction to a satellite's position, plus a velocity vector, plus a time offset correcting the atomic clock, plus administrative details ('issue of data number') 2/2
Ok, the data is here: berthub.eu/galileo/galile…
C/NAV for 2,25,8 means this is a signal from Galileo (2) satellite E25 over E6 (8). Slide 16 and onwards of geopp.com/pdf/gpp_ppprtk… may be helpful.
Feel free to drop by the #galileo IRC channel on irc.oftc.net -> webchat.oftc.net/?channels=gali…, where there is lots of expertise to guide your reverse engineering.
Ok! It turns out an earlier version of a spec is available on the EU eTendering site! I suspect this will be pretty close: etendering.ted.europa.eu/document/docum… from etendering.ted.europa.eu/cft/cft-docume…
If you are trying to make sense of my data, know there is byte order pain in there & also missing data. Best wait it out a bit until I verify it is at least making some kind of sense.
The checksums match the spec! Something is working! Sadly, the satellites are currently broadcasting dummy data.. but at least the checksums are making sense now!
Found the dummy marker AF3BC3 in there! This is a real bitstream protocol that does not respect your byte boundaries. Space protocols tend to be like that.
Actual payload that looks valid! Status 1 = valid data, Message Type (MT) 1 = "Contains satellite
corrections", Message Size (MS) 1 = actually 2 pages per message. Next up, Reed-Solomon!
Some light reading ahead..
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