[Xastir] GPS

[Tom Russo]

On Wed, May 17, 2023 at 07:14:44PM -0500, we recorded a bogon-computron collision of the <kg4wsv at gmail.com> flavor, containing:
> Check your baud rate and make sure xastir and the gps matches. 
> 
> The standard for NMEA is 4800 but newer receivers may default to a higher baud rate. 
> 
> If you can???t find what cgps is using for a baud rate, stop cgps and connect with a terminal app (e.g. minicom, tio). 

Since you're using cgps, you must be using gpsd.  And if gpsd is able to
process the data properly so that cgps can display it, then baud rate 
probably isn't the issue.

The question then is why Xastir's not showing the fix right.  I can't account
for why your GPS Status info shows "invalid fix" and your station info
shows the correct position unless you had somehow already put the correct
static position into your station configuration or positioned your station
manually.

How is your "networked gps (via gpsd)" interface configured?  

And again, what version of Xastir are you running?  Did you build it yourself
from source code or is it from your system's package management system?  

What GPS unit are you using?

It may also be helpful to use debug level 128 and view what Xastir is saying
about GPS data in the console.  This requires that you launch Xastir from the
command line and not from a desktop shortcut or menu, so that you can see
those messages in the terminal window.  If you launch from a desktop icon or
menu, there is no terminal window in which they can be displayed and who knows
where they might be found.

The debug level can be changed using File->Configure->Change Debug Level.

You're looking for what type of sentences Xastir is receiving.  Xastir 2.1.8
and later will accept anything of the form $xxGGA and $xxRMC (where xx is 
anything at all), but prior to that only accepted $GPGGA and $GPRMC sentences.

I should note that the bug I mentioned earlier regarding Xastir not recognizing
fixes from units that report other than GPS satellite fixes was detected
precisely because someone was using gpsd and Xastir was refusing to recognize
positions from the attached GPS.  It was reported as a problem of Xastir not 
working with gpsd, but after a while we tracked it down to specifics of how 
that user's "GPS" unit was outputting NMEA sentences --- it was outputting 
$GNGGA and $GNRMC (GNSS sententences), but Xastir had been hard coded to expect 
only $GPGGA and $GPRMC.  It would ignore *everything* else.  That user found 
that Xastir was always reporting invalid fix, even though gpsd and all its 
various display clients seemed to be perfectly happy.

This issue (https://github.com/Xastir/Xastir/issues/53) was fixed in 2019 and
is present in Xastir 2.1.2 and later, and there were further refinements 
after that (to support $II sentences, 
https://github.com/Xastir/Xastir/issues/121).  But you'd have to be running at 
least that recent a version --- so I ask again, which version are you running, 
is it one you compiled yourself from source code or one that you installed from 
a package management system?  

The fix for $II sentences (Integrated Instruments devices) didn't get done 
properly until after release 2.1.8.  If your GPS is sending *those* then 
you've got to have the development branch code, not a release version.  

> > On May 17, 2023, at 6:35 PM, Phil <phillor9 at gmail.com> wrote:
> > 
> > ???I've rigged up a GPS receiver but Xastir is showing an invalid position.
> > 
> > The red arrow at the bottom of the screen is blinking at a one second rate, the same rate as the GPS receiver indicator, and the data rate is correct.  cgps -s displays my current location correctly.
> > 
> > Any ideas?
> > 
> > -- 
> > Regards,
> > Phil
> > 
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-- 
Tom Russo    KM5VY
Tijeras, NM  

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