On Mon, Feb 28, 2022 at 1:12 PM Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
On Mon, Feb 28, 2022 at 10:37:09AM +0100, Gabriele Coppi wrote:
> On Mon, Feb 28, 2022 at 8:46 AM Miroslav Lichvar <mlichvar@xxxxxxxxxx>
> wrote:
> > On Fri, Feb 25, 2022 at 12:10:40PM +0100, Gabriele Coppi wrote:
> > > refclock SHM 0 precision 1e-1 delay 0.5 refid GPS
> > > refclock SHM 1 precision 1e-7 refid PPS
> >
> > You should remove the first source and just rely on the PPS-based
> > SHM 1, or alternatively use SHM 0 + PPS /dev/pps0. SHM 1 from gpsd is
> > sufficient.
> >
>
> I am using the SHM1 because the /dev/pps0 it is always reported as a
> falseticker. I checked with ppstest and I got out the signal, so I don't
> know why
As a falseticker against SHM 0, or some NTP server? If the latter, it
might be using the wrong edge of the pulse.
Now it seems working also using
refclock PPS /dev/pps0 precision 1e-7 refid PPS
instead of the SHM1 PPS signal. However, I am still getting falseticker after ~15min from both PPS and SHM0 sources. I will try to use only the PPS now based on what you wrote below
> > If you see both sources marked as falsetickers (x symbol) in the
> > chronyc sources output, that means they don't agree with each other.
> > If the offset of the SHM 0 is around 0.25s, small changes in the delay
> > would cause the behaviour you see.
> >
>
> Yes, the offset of SHM0 is always between 250 and 500ms.
That should be compensated with the offset option. But better it is to
not use the SHM 0 at all. As you see, its offset is too variable.
--
Miroslav Lichvar
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