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Re: gpsd-users Digest, Vol 104, Issue 3

From: Gary E. Miller
Subject: Re: gpsd-users Digest, Vol 104, Issue 3
Date: Fri, 4 Sep 2020 10:02:49 -0700

Yo Bradley!

On Fri, 4 Sep 2020 12:50:36 -0400
Bradley McFadden <> wrote:

> Hey Gary!
> Your help is allowing me to make some progress on this problem.
> Thanks!
> > Does it send NMEA, by default, when you turn it on?  Otherwise not
> > gonna work with gpsd.  
> > > > > I can read data from this device using:
> > > > > stty -F /dev/ttyXTRX0 speed 9600 && cat /dev/ttyXTRX0.  
> > > > You fail to note whehter that is as root, or a user.  
> > >
> > > This command is being run as user.  
> > A user in the dialout group?  
> Yes, the user is in the dialout group.
> sail@gr110:~/workarea/workarea/gr-fosphor/build$ groups
> sail adm dialout cdrom sudo dip plugdev lxd wireshark

And so, I guess, not roor.  Not being root breaks a lot of gpsd.

> > What does the cat show you?  
> The cat seems to be showing me NMEA data.

If cat can not open the port, then gpsd can not open the port.

Alsways stop at the first failure.  Not bbeing able to cat is
your first failure.  Ignore gpsd until you fix that.

> I know that the XTRX
> doesn't have satellite lock, but I'm more
> concerned with gpsd being able to read from the device at the moment.

Do not be.  Be concerned that cat can not read the device.

> sail@gr110:~/workarea/workarea/gr-fosphor/build$ stty -F /dev/ttyXTRX0
> speed 9600 && cat /dev/ttyXTRX0
> 9600
> �$PMTK011,MTKGPS*08
> $PMTK010,001*2E
> $PMTK011,MTKGPS*08
> $PMTK010,002*2D
> $PMTK011,MTKGPS$PMTK001,10,1*03
> $PMTK011,MTKGPS$PMTK001,10,1*03
> $GNGGA,235942.870,,,,,0,0,,,M,,M,,*52
> $GPGSA,A,1,,,,,,,,,,,,,,,*1E
> $GLGSA,A,1,,,,,,,,,,,,,,,*02
> $GPGSV,1,1,00*79

You just said cat read nothing.  And now cat read something?
What changed?  This is not Shreodinger's Cat.  It can not be both ways
at the same time.

> > You gotta make a choice, are you going to run gpsd under
> > systemd(umber), or not.  You can not do both.  
> I found the systemd services that gpsd used with this command:

Did you read the gpsd systemd(umbest) doc?

> After disabling the services systemd was running, port 2947 cleared
> up, and I no longer got an error
> about port 2947 being in use.

Which, of course, is expalined in the gpsd doc on systemd(reck).

And what does this show:
        netstat -apn | fgrep 2974

> > Try this, as root:
> >       lsof /dev/ttyXRX0  
> root@gr110:/home/sail/workarea/workarea/gr-fosphor/build# lsof
> /dev/ttyXTRX0 lsof: WARNING: can't stat() fuse file system
> /run/user/1000/doc Output information may be incomplete.

Something wrong with your system as that did not work.

What distro is this again?

Until "lsof /dev/ttyXRX0" works, no point trying gpsd.

> > Run gpsd as root, or do not bother.  Running as not root breaks
> > things that you are not prepared to deal with.  
> Will do. This is the output. Same permission error as before.
> root@gr110:/home/sail/workarea/icmtgui-dev# gpsd -n -N /dev/ttyXTRX0
> gpsd:ERROR: SER: device open of /dev/ttyXTRX0 failed: Permission
> denied - retrying read-only

So, once again. did cat on the port work, or not?  You said both.

> > Fun, another stingray clone?  
> Yeah, that's the idea of the project. The idea is to do the RF side of
> things with a software based radio
> we can listen to any frequency and perform different demodulations.
> In this way we hope to be able to
> detect and identify as much as possible with just an XTRX and a second
> radio that goes up to 6GHz.

All this work to save a $20 GPS?

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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