[Xastir] GPS NMEA sentences decoded by Xastir

[Menga]

before trying to solve the problem to decode NMEA sentences with different 
preambles in general, I tested the simple case where are decoded together 
with GPRMC, GPGGA  also IIRMC, IIGGA, that mostly interests me.
The file is gps.c. Apparenlty the job is quite simple by adding AND (&&) and 
OR (||) in two points of the program where the presence of "$GPRMC," and 
"GPGGA," is verified.
I checket before the sentences in the two cases GP , and II: they are 
(almost) identical but some fields with numbers in one case are int 3456, in 
the other float 3456.00. But that should not matter.
Because the checksum is not tested I also made a second experiment by 
substituting just entering into the decoding function in the second and 
third position of the string  to my premable II, the value  GP .
The results were in both cases unsuccessful. I don't have on the boat great 
debuggin facilities and the computer is raspberry pi, so I wasn't able to 
debug more deeply.
In the right lowest corner of the xastir window I was seeing the mark 
blinking periodically, but on the map the position was not updated.
Some suggestion o explain me which is the problem, or instructions for 
entering into debugging mode?
Giuseppe
IZ1GCL/IS0/MM
-----Messaggio originale----- 
From: Tom Russo
Sent: Friday, July 21, 2017 6:37 AM
To: Xastir - APRS client software discussion
Subject: Re: [Xastir] GPS NMEA sentences decoded by Xastir

On Fri, Jul 21, 2017 at 06:33:38AM +0200, we recorded a bogon-computron 
collision of the <giuseppe.menga at polito.it> flavor, containing:
> I noted in the file gps.c of the Xastir sources two problems in the 
> decoding
> of GPS NMEA sentences: only two types of sentences are decoded $GPRMC and
> $GPGGA, no checksum is tested.
> GPS devices have many different preambles, just in my case $IIRMC and
> $IIGGA, II stands for integrated instruments, but there are many others 
> that
> are banned from Xastir.
> Moreover, a control of the checksum is not complicate and it can be added.
> I ask to the developers a comment on this issue, and in the case I can 
> offer
> a proposal for modification.

If you can code it in yourself, go ahead and make a fork on GitHub, do the
work on a branch, and issue a pull request.  So long as it doesn't break
any other use cases, we'll very likely just merge it.

I don't think either Curt or I have GPS units that produce those sentences,
and I don't have time to work on it myself.  I can't speak for Curt, but I
think he's pretty busy these days, too.  If you can't do the coding 
yourself,
this might take longer than it might seem.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 
http://kevan.org/brain.cgi?DDTNM
echo "prpv_a'rfg_cnf_har_cvcr" | sed -e 's/_/ /g' | tr [a-m][n-z] [n-z][a-m]




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