Re: [chrony-users] Re: Locking PPS refclock with NTP source

210 Number of sources = 2
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* PPS0 0 4 377 11 +4829ns[+6161ns] +/- 3021ns
^- 10.30.121.241 1 6 377 6 -51us[ -50us ] +/- 154us
210 Number of sources = 2
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
PPS0 23 17 383 +0.001 0.052 +5ns 5548ns
10.30.121.241 6 3 325 -0.085 0.323 -41us 7468ns

I am using pps_ldisc, i tried pps-gpio but it was not better.

I am using a custom serial cable (pin 1 of the serial cable is linked to the bnc ouput on the gps timeserver), same setup had given good results using an other software.

2017-08-29 15:55 GMT+02:00 Miroslav Lichvar <mlichvar@xxxxxxxxxx>:

On Tue, Aug 29, 2017 at 02:58:20PM +0200, Thibaut BEYLER wrote:
> Thanks, this is working indeed, but should i get good results (like, not
> more than a few of micros from my gps time) with these settings ?

You should get the same results as if the PPS refclock was locked to a
NMEA source for instance. The lock option is mainly useful to speed up
the initial synchronization and allow the noselect option to be
specified with the NMEA or other low quality refclocks.

> Right now it is locking on PPS (*) but my clock seem worse (offset to utc)
> than when using only the ntp server as source.

Can you please post the output of "chronyc -n -m sources sourcestats" ?

What hardware and what PPS driver (e.g. serial, gpio) do you use?
Typically, on a x86_64 machine with a GPS PPS and real serial port the
offset should be stable to a microsecond or better.

--
Miroslav Lichvar

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