[Xastir] How to get CWOP weather on APRS network
Curt Mills
curt.we7u at gmail.com
Thu Jan 20 11:00:57 PST 2022
It's fuzzy in my memory now, but I believe there may be a side-effect
in Xastir as well (which can be taken advantage of in some cases)
where if the call and SSID are the same as the Xastir instance when
injecting packets in via xastir_udp_client, Xastir can take up
re-transmitting those packets at intervals. Like I said it's a bit
fuzzy now as I haven't messed with that piece for some time.
Where it can be and advantage is if you're trying to inject
objects/items into Xastir from some other interface, using
xastir_udp_client to do this injection.
Of course the side-effect is if you don't desire Xastir to pick up the
transmission as it's own and retransmit it. I believe this can be
solved by using a different SSID and/or callsign for the injection.
On Thu, Jan 20, 2022 at 10:50 AM Tom Russo <russo at bogodyn.org> wrote:
>
> Resurrecting an ancient thread, because Dj opened an issue on GitHub about it
> this week, and I tracked down what is happening here. I'm following up to
> the original thread to clear up the misunderstanding and get the answer into
> the mailing list archive where it could presumably be found in web searches.
>
> Dj had Xastir and WeeWx's APRS extension working, but only by modifying
> main.c.
>
> The reason for the suggested mods of main.c in the message I'm replying to
> is to work around some mistaken usage of xastir_udp_client, which I think
> may have been the result of some incomplete (or perhaps overly vague)
> documentation.
>
> xastir_udp_client does NOT insert the packet header "FROMCALL>TOCALL:" into
> the data passed to it on the command line, it does a straight insersion of
> the data passed to it directly into Xastir's incoming packet stream. And so
> one MUST include "FROMCALL>TOCALL:" at the beginning of the packet oneself.
> Some other APRS tools for injecting packets do this for you, but
> xastir_udp_client does not.
>
> Once injected, Xastir creates a third-party packet out of the data. Third
> party packets look like "xastircall>APX219,PATH1,PATH2...:}tpcall>tocall:..."
> where "xastircall" is the call sign of the Xastir instance and "tpcall" is the
> call sign of the third party station (which may be the same as Xastir's).
> When properly formatted, these packets show up in APRS clients (including web
> based ones like aprs.fi) as being from tpcall.
>
> The main.c changes Dj mentions here basically break the third-party insertion
> and mask the fact that he's left out the packet header in what he's passed to
> xastir_udp_client. The fact that he was leaving out "tpcall>tocall:" was
> why his packets were being flagged as invalid without those
> modifications (the stuff after the "}" was incomplete).
>
> Once that usage error is corrected, Xastir should be able to take WeeWx's data
> just fine. So the script to do the insertion would be:
>
> #!/bin/bash
> #
> weatherpacket=`cat /dev/shm/aprs.pkt`
> /usr/local/xastir/bin/xastir_udp_client localhost 2023 YOURCALL XXXX -to_rf
> "YOURCALL>APX219:$weatherpacket"
>
>
> with the obvious modification to make it correct for your call sign. This
> will work with Xastir unmodified, and is as xastir_udp_client was meant
> to be invoked.
>
> I have examined the xastir_udp_client man page and found it to leave too much
> to interpretation. I edited it and added more notes about how it really works
> so that perhaps it will be easier for others to grok in the future. If anyone
> still finds it confusing, I can modify it further.
>
> On Sat, Oct 31, 2020 at 08:30:18PM -0400, we recorded a bogon-computron collision of the <xastir at deej.net> flavor, containing:
> > On 10/30/2020 1:07 AM, Steven Morrison wrote:
> > > I can configure the WeeWx program to generate a report and send it to the
> > xastir Pi, but how can i receive that report and transmit it in xastir?
> >
> >
> > I'm doing it as follows in Linux (Raspberry Pi) with both WeeWx and Xastir
> > running on the same RPi, but you could easily rsync the /dev/shm/aprs.kpt
> > file to a different computer if needed.
> >
> > I have the APRS extension loaded into WeeWx
> > (https://github.com/cavedon/weewx-aprs).
> >
> > In /etc/weewx/weewx.conf I have:
> >
> > # Options for extension 'aprs'
> > [APRS]
> > comment = "RaspberryPi-Xastir-Wx-Topsham,ME"
> > include_position = 1
> > symbol_code = _
> > symbol_table = /
> > output_filename = /dev/shm/aprs.pkt
> >
> >
> > Then I have a crontab entry that does:
> >
> > 01,11,21,31,41,51 * * * * /home/xastir/scripts/send-weather-rf.sh >
> > /dev/null
> >
> >
> > and the send-weather-rf.sh script looks like (XXXX is my 4 digit APRS code):
> >
> > #!/bin/bash
> > #
> > weatherpacket=`cat /dev/shm/aprs.pkt`
> > /usr/local/xastir/bin/xastir_udp_client localhost 2023 N1JOV XXXX -to_rf
> > $weatherpacket
> >
> >
> > I am using an older version of Xastar (2.1.1) compiled from source code, and
> > had to make the following change in main.c to make the xastir_udp_client
> > command work for the above. I do not know if this still needs to be done in
> > later versions.
> >
> > main.c is my custom version, main.c.orig is the original.
> >
> > $ diff main.c main.c.orig
> > 12180,12183c12180,12183
> > < // char path[100+1];
> > < // char info[100+1];
> > < // char *path0 = NULL;
> > < // char *info0 = NULL;
> > ---
> > > char path[100+1];
> > > char info[100+1];
> > > char *path0 = NULL;
> > > char *info0 = NULL;
> > 12187,12188c12187,12188
> > < // path0 = strtok(line,":"); // Pointer to
> > start of path
> > < // info0 = strtok(NULL,""); // Pointer to
> > information field
> > ---
> > > path0 = strtok(line,":"); // Pointer to
> > start of path
> > > info0 = strtok(NULL,""); // Pointer to
> > information field
> > 12190,12197c12190,12196
> > < // xastir_snprintf(path, sizeof(path), "%s",
> > path0);
> > < // xastir_snprintf(info, sizeof(info), "%s",
> > info0);
> > < // //fprintf(stderr, "path: %s\n", path);
> > < // //fprintf(stderr, "info: %s\n", info);
> > < // //fprintf(stderr, "line: %s\n", line);
> > < // xastir_snprintf(line, sizeof(line),
> > "%s%s%s", path, ",NOGATE:", info);
> > < // xastir_snprintf(line, sizeof(line),
> > "%s%s%s", path);
> > < // //fprintf(stderr, "line: %s\n", line);
> > ---
> > > xastir_snprintf(path, sizeof(path), "%s",
> > path0);
> > > xastir_snprintf(info, sizeof(info), "%s",
> > info0);
> > > //fprintf(stderr, "path: %s\n", path);
> > > //fprintf(stderr, "info: %s\n", info);
> > > //fprintf(stderr, "line: %s\n", line);
> > > xastir_snprintf(line, sizeof(line), "%s%s%s",
> > path, ",NOGATE:", info);
> > > //fprintf(stderr, "line: %s\n", line);
> > 12239c12238
> > < // *(line + line_offset - 1) = '}';
> > ---
> > > *(line + line_offset - 1) = '}';
> > 12242,12243c12241
> > < // (char *)(line + line_offset - 1), //
> > Raw data line
> > < (char *)(line + line_offset), // Raw data
> > line
> > ---
> > > (char *)(line + line_offset - 1), // Raw
> > data line
> >
> >
> > -Dj
> >
> >
> > --
> > Dj Merrill - N1JOV - EAA Chapter 87
> > Currently Flying: Glastar
> > Previously: Cessna 150 - Glasair 1 FT - Grumman AA1B
> >
> > _______________________________________________
> > Xastir mailing list
> > Xastir at lists.xastir.org
> > http://xastir.org/mailman/listinfo/xastir
>
> --
> Tom Russo KM5VY
> Tijeras, NM
>
> echo "prpv_a'rfg_cnf_har_cvcr" | sed -e 's/_/ /g' | tr [a-m][n-z] [n-z][a-m]
>
> _______________________________________________
> Xastir mailing list
> Xastir at lists.xastir.org
> http://xastir.org/mailman/listinfo/xastir
--
Curt, WE7U http://xastir.org http://www.sarguydigital.com
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