Re: gpsd + chrony + pps

[Gary E. Miller]

Yo Stéphane!

On Fri, 19 Jun 2020 15:36:36 +0200
Stéphane Péneau <stephane.peneau@wanadoo.fr> wrote:

> gpsd:
> 
> DEVICES="/dev/ttyS1 /dev/pps0"
> # Other options you want to pass to gpsd
> GPSD_OPTIONS="-n -b -s 115200"
> # Automatically hot add/remove USB GPS devices via gpsdctl
> USBAUTO="false"

I have no idea what the above refers to, it is not part of gpsd.

I need to know how gpsd is running, as root:
        # pstree -paul | fgrep gpsd
        # netstat -apn | fgrep 2947

> chrony.conf:
> 
> refclock SHM 0 refid GNSS precision 1e-1 offset 0.150 delay 0.2
> noselect refclock SOCK /var/run/chrony.ttyS1.sock refid PPS2 lock GNSS

Why SHM and SOCK?  They reference the same source (NMEA serial) and have
the same data.  That is an either/or.  Why are you locking a signal to
itself?  I cleaned up the doc last night to make that clearer.

ttyS1 would be GPS, not PPS, or PPS2.

Your PPS will be on SHM(1) and /var/run/chrony.pps0.sock

Where did "lock GNSS" come from?  You are reading from a sock, with
fully corrected time.  That is when chronyd is reading the raw PPS.

> refclock SHM 0 refid GNSS precision 1e-1 offset 0.150 delay 0.2
> noselect refclock SOCK /var/run/chrony.pps0.sock refid PPS2 lock GNSS

Still mixing SHM and SOCK.  Pick one method or the other.

Where did "lock GNSS" come from?  You are reading from a sock, with
fully corrected time.  That is when chronyd is reading the raw PPS.

Check out the doc as it stands today.

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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