Now that's interesting... We have gps.c:nmea_checksum() which does compute the checksum. It's not used in the GPS decoding, but is used in gps.c:create_garmin_waypoint()
It's likely that function could be repurposed to compute the GPS checksum for the decoding as well, then compared against the checksum we received. On Thu, Apr 11, 2019 at 1:06 PM Curt Mills <[email protected]> wrote: > To answer Jason's question about checksum, no I don't think we check it. > We probably should. > > Also: APRS _can_ have increased resolution: Use APRS compressed mode. I > used to do that a lot, and it gives you precision of about a 2' by 3' > rectangle. > > On Thu, Apr 11, 2019 at 1:02 PM Tom Russo <[email protected]> wrote: > >> I should point out that these updates only refer to handling of attached >> location receivers, and do not add support for raw NMEA posits as Jason >> had suggested. It should not be super difficult to add that support, but >> it isn't done yet. >> >> On Thu, Apr 11, 2019 at 01:58:30PM -0600, we recorded a bogon-computron >> collision of the <[email protected]> flavor, containing: >> > GNSS, GLONASS, Beidou, and Gallileo support is no on the main branch of >> > the Xastir repo, no fork needed. Update your clone, and you should be >> able >> > to use Xastir with multi-constellation receivers now. So far it has >> only been >> > tested with GPS and GNSS receivers, but it should work with all the >> others. >> > >> > If you try it and it doesn't work, please open a bug report on GitHub, >> and >> > we'll run it to ground. >> > >> > On Wed, Apr 10, 2019 at 10:56:38PM -0600, we recorded a bogon-computron >> collision of the <[email protected]> flavor, containing: >> > > Turns out that the GNGGA/GNRMC vs. GPGGA/GNGGA issue is the reason for >> > > the newly opened issue #53 on github ( >> https://github.com/Xastir/Xastir/issues/53), >> > > and I believe I have it fixed with pull request #58 ( >> https://github.com/Xastir/Xastir/pull/58) >> > > >> > > If any users with GLONASS receivers that emit GNGGA/GNRMC sentences >> (such >> > > as the DRAWS hat for Raspberry Pi) would like to test it out, >> > > you can get it via: >> > > >> > > cd <your clone> >> > > git checkout master >> > > git checkout -b tvrusso-feature-supportglonass master >> > > git pull https://github.com/tvrusso/Xastir.git >> feature-supportglonass >> > > >> > > Then rebuild Xastir and try it out. >> > > >> > > The more folks I can get testing this the better. I won't merge to >> master >> > > until I at least confirm that it helps the GN vs. GP thing. As far >> as I can >> > > tell so far, I haven't borken it for GP. >> > > >> > > On Sun, Dec 02, 2018 at 02:52:06PM -0600, we recorded a >> bogon-computron collision of the <[email protected]> flavor, containing: >> > > > I just started playing with a u-blox 8 family GPS. It's capable of >> > > > receiving multiple GNSS simultaneously. At first glance this unit >> doubles >> > > > the number of available satellites just because it's listening to >> GLONASS >> > > > and GPS at the same time. >> > > > >> > > > Of course there's a downside. In APRS-land we're used to dealing >> with a >> > > > single "talker ID" that indicates we're dealing with GPS (the name >> of the >> > > > US system) - that's the "GP" in GPGGA and GPRMC. This system uses >> GN as the >> > > > talker ID when it's listening to multiple systems. I can configure >> it to >> > > > use GPS only and get my familiar GPGGA, but I stop listening to a >> bunch of >> > > > available satellites when I do that. >> > > > >> > > > Since APRS has limited resolution we (APRS users) wouldn't benefit >> much >> > > > from increased accuracy, but we would get something from having a >> much >> > > > larger constellation available. >> > > > >> > > > Has anyone messed with these multi-GNSS receivers? Are the benefits >> that >> > > > seem obvious at first glance real? >> > > > >> > > > Would it be appropriate to think about code changes to Xastir (or >> other >> > > > clients but i don't use those) to use G[PLABN]GGA or G[PLABN]RMC >> instead of >> > > > restricting ourselves to GP only? There would be 2 cases here, once >> for the >> > > > attached GPS interface to determine our position, and the GPGGA >> APRS packet >> > > > type. I'm actually considering using GGA and RMC packets to get >> increased >> > > > resolution on a non-144.39 tracking application. >> > > > >> > > > Does xastir verify the NMEA checksum from an attached GPS? >> > > > >> > > > -Jason >> > > > kg4wsv >> > > > _______________________________________________ >> > > > Xastir mailing list >> > > > [email protected] >> > > > 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] >> > >> > -- >> > 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] >> >> -- >> 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 >> [email protected] >> http://xastir.org/mailman/listinfo/xastir >> > > > -- > Curt, WE7U http://we7u.wetnet.net > http://www.sarguydigital.com > -- Curt, WE7U http://we7u.wetnet.net http://www.sarguydigital.com _______________________________________________ Xastir mailing list [email protected] http://xastir.org/mailman/listinfo/xastir
