Re: gpsd-users Digest, Vol 104, Issue 1

[Gary E. Miller]

Yo Bradley!

On Thu, 3 Sep 2020 13:06:46 -0400
Bradley McFadden <bmcfadden@laurentian.ca> wrote:

> > What is this XTRX you speak of?  Why?  
> The XTRX is a software defined radio that also happens to have an
> onboard gps.

Does it send NMEA, by default, when you turn it on?  Otherwise not
gonna work with gpsd.

> The reason I'm using this is to look for activity on various cell
> towers in the area.

Fun, another stingray clone?

> I have an application with a large (42 million line) database of
> these cell towers that
> takes a large amount of time to search for nearby towers.

I don't call that large.

> I want to be
> remember what I found
> in different locations so I can avoid searching the database. For
> that, I want to use the XTRX's
> gps.

Sounds like you are just creating a second database of found files.  Many
other ways to skin that cat.  But no matter what you want your location,
and that is what gpsd gives you.

> I've followed the setup instructions for the XTRX, directly from their
> github page:
> https://github.com/xtrx-sdr/images#how-to-use-xtrx-gps-to-receive-nmea-data-and-pps-signal

Wow, a lot of work to replace a $20 GPS.  And pretty distro specific.

> > 1. What distro?
> > 2. What version of gpsd?
> > 3. Did you build gpsd, or is it from a package?  
> I'm running on Ubuntu 20.04, with GPSd version 3.20, which was
> installed by the apt package manager.

You realize that package did not come from here?  We can provide general
help, but we have no control over the package.

> > Better to show than paraphrase.  What does this show:
> > $ ls -l /dev/ttyXTRX0  
> The output permissions on /dev/ttyXTRX0 are as follows:
> sail@gr110:~/workarea/examples$ ls -l /dev/ttyXTRX0
> crw-rw---- 1 root dialout 234, 64 Sep  3 07:58 /dev/ttyXTRX0

Since you need to start gpsd as root, that is OK.

> >> 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?  What does the cat show you?

> > 2. "-S 3900".  Why are you using TPC port 3900??  
> I'm using port 3900 because port 2947 seems to be taken.

Ooops.

> $ sudo netstat -pnlt | grep 2947
> tcp         0      0 127.0.0.1:2947      0.0.0.0:*           LISTEN
>  1/init
> tcp6       0      0 ::1:2947                 :::*
> LISTEN 1/init

You are already running gpsd under systemd(umb)!  Don't do that!
It is not just the TCP port the two daemons are fighting for.

You gotta make a choice, are you going to run gpsd under systemd(umber),
or not.  You can not do both.

> > This error doesn't make sense to me as I've checked that the user
> > and gpsd are both in the dialout group.  
> >> Uh, remember that sudo?  You are not running as "user'.  
> 
> I get the same output here when I do run as user:

Run gpsd as root, or do not bother.  Running as not root breaks things
that you are not prepared to deal with.

Try this, as root:
        lsof /dev/ttyXRX0

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  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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