20 Jul
2019
20 Jul
'19
12:08 p.m.
On Fri, 19 Jul 2019 at 15:58, Brad Walker <bwalker(a)musings.com> wrote:
I've been studying the rtl_adsb.c code and
it's very interesting how it
works..
But, I have question.
I noticed that if I request verbose output using the "-V" option, then the
CRC is printed out. But, it doesn't look like the code actually does any
Reed-Soloman error correction to the data the ADS-B specification
documents.
1090MHz (Mode S extended squitter) ADS-B does not use R-S error correction,
it's just a 24-bit CRC (or an xor of that with the aircraft address for
some message types). Maybe you are thinking of 978Mhz (UAT) ADS-B, which is
not handled by rtl_adsb at all?
There is some error correction that's possible even with just the CRC but
it's not particularly reliable.
Oliver