Re: [chrony-users] Trouble with PPS

[Alvaro Gamez <alvaro.gamez@xxxxxxxxxx>]

2018-04-17 1:23 GMT+02:00 Simon Haines <simon@xxxxxxxxxxxxxxxx>:

Also note that gpsd can sometimes erroneously create a second PPS source, thinking that the GPS device is connected with the serial line discipline exposing the PPS on a serial port pin. You can cross-check with ppstest, but your kernel debug seems to suggest that the source is indeed pps0.

Simon.

Yes, there's only one PPS source and gpsd is behaving as it should.

 

On Mon, Apr 16, 2018 at 5:23 PM Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:

On Mon, Apr 16, 2018 at 09:01:11AM +0200, Alvaro Gamez wrote:
> I've tried your configuration (main difference was only the offset values).
> It sometimes seems to work, but not always.
>
> Here's a series of 'sources' requests output:
> #* GPS                           0   4    77    18    +90ms[ +306ms] +/-
> 6773us
> #? PPS                           0   4     6    39   -290ms[  -74ms] +/-
> 1622us

It seems the offset between the two refclocks is still too large to
allow a reliable lock of the PPS. Try increasing the offset of the SHM
refclock to 0.5.

Ah! That seems to be doing the trick!

#- GPS                           0   4   377    28    +11ms[  +11ms] +/- 9045us
#* PPS                           0   4   377    27   +109us[ +105us] +/-  388us

Why is GPS marked as not combined, though?

Thanks!

--

Álvaro Gámez Machado