ntpsec is ignoring PPS

folkert folkert at vanheusden.com
Tue Nov 30 21:25:00 UTC 2021

> > ntpq shows:
> >
> > root at gpsdomonitor:~# ntpq -c pe -n
> >      remote           refid      st t when poll reach   delay   offset
> > jitter
> > oPPS(0)          .PPS.            0 l   12   16  377   0.0000  -0.0114  0.0040
> > xPPS(1)          .PPS.            0 l    1    2  377   0.0000 490.4861  0.0065
> >  nl.pool.ntp.org .POOL.          16 p    -   64    0   0.0000   0.0000  0.0019
> What are the units of offset?  Is it just that PPS1 is offset so much it

These are milliseconds.

> is flagged as a bad clock?  Especially if it is considered a stratum 0
> clock it should not be that far off.

Not sure. But as Gary suggested, I'll let it sit for a while to see if
it helps.

> > PPS(0) is a regular garmin lvc18, while PPS(1) is a GPS disciplined
> > osc...that is divided to 1PPS using a "picdiv"
> Are you using PD11 and synchronizing to a known good PPS to get the output
> synchronized to true top-of-second?  If you just divide 10MHz down to 1Hz
> you will get some random offset up to +/-500ms from the true top of
> second.

That's a very good point!
I am using a PD10 currently so yes that explains that offset. Thanks for
pointing me at that.
I'll see if I can flash a PD11 myself (sofar my aliexpress burner fails
to do so) or buy one from Tom van Baak.


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