Re: Help needed with USB GPS device

[Gary E. Miller]

Yo Gavin!

On Wed, 28 Feb 2024 22:17:18 +0000
Gavin Davenport <gavdav@gavdav.net> wrote:

> I'm trying to determine why my GPS device isnt' feeding a time source
> to chrony (Fedora release 38 system)

It helps if you tell us what model GPS you have.  

> Initialisation of gpsd seems to have been wrapped into system and I
> can see there's a gpsd service and a gpsd.socket unit file.

Not very informative either.  You are trying to debug the problem
from the wrong direction.  Always start at the First Failure.  Not
the last one.  So before you look at chrony, you need to have a good
lat/lon from gpsd.

How about I stop you right here, and ask you to run gpsdebuginfo,a as
root, nut under sudo, and send us the results.

You can find the latest version here:

    https://gpsd.io/gpsdebuginfo

But one thing to note, your USB GPS does not have PPS.  Very few USB
GPS have PPS.

> ppstest says
> [root@roundabout ~]# ppstest /dev/ttyUSB0
> trying PPS source "/dev/ttyUSB0"
> cannot create a PPS source from device "/dev/ttyUSB0" (Operation not
> supported)

So you timing accuracy will be a few 100 milliseconds.:  Is that good enough
for you?

> Is there an idiots guide of building the relevant components up that
> I can follow ?

Several.  Check out our home page:

    https://gpsd.io/

The Timeservice howto is a good start:

    https://gpsd.io/gpsd-time-service-howto.html



RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  Tel:+1 541 382 8588

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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