[aprssig] Protocol parsing questions
bruninga at usna.edu
Thu Nov 20 15:44:13 CST 2008
There are two documents written to help you parse APRS:
The first one makes sure that you at least estimate a vicinity
plot on a new callsign no matter what his packet, so that he
exists within your system with the best guess position until you
subsequently get a valid posit.
The second document above shows you the process for working your
way through the parser. If a packet passes all the way through
the parser and does not match any formats, then put it in the
BAD-PACKET list. But if it is the only packet you have received
from a station, then put it in the STATUS list as the best info
you have from that station.
> -----Original Message-----
> I'm getting back into APRS after a few years (oh, about 15, I
> think). I'm in the process of writing a ground-up Java
> parser, as my eventual goal is to run a native application on
> the Android G1 that uses it as a position reporting device.
> I've run across a few packets that I can't determine the
> contents of based on the 1.0.1 and 1.1 specifications. For
> example, the packet below:
> We have a 'g000' that says what the gust is. Then we have a
> 'gt41...' I have no idea what that is. There's also the
> question of when to stop parsing, and treat the remainder as
> a comment. In the 1.0.1 PDF file, a number of the example
> weather packets are shown with 'wRSW'. 'w' should be the
> software version, but it's not define in the list that
> follows. Is there a known sigil for deciding the remainder
> of the packet are comments?
> I also see a number of improperly formatted packets hitting
> aprs-is. Like this one:
> Note the incomplete speed field. What's the appropriate
> course of action? Discard it?
> Then there are these packets:
> I'm guessing these might be a QSO or something, but I don't
> understand how to programmatically identify them.
> Can someone point me to some documentation i might be
> overlooking? Or provide some insight from experience?
> --jc (K4JCW)
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