Re: refclock local

It means that your PPS source is way out of line with the toher two sources
(half a second different) and thus is an outlier.It has small scatter ( 31us
rathee than the ms of the others).but still lies well outside the other two
sources.So chrony is not going to select it and feels that it is not to
betrusted.




William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ [email protected]
Canada V6T 1Z1 ____|____ and Gravity ______|_    theory.physics.ubc.ca/

On Mon, 7 Aug 2023, Josef 'Jeff' Sipek wrote:

> [CAUTION: Non-UBC Email]
>
> I did an experiment tonight to see if I understood chrony's local refclock
> support.
>
> I connected a signal generator running at 1Hz to a serial-to-USB's CTS pin,
> told the (FreeBSD) kernel to capture PPS pulses from that pin, and
> configured chrony with (in addition to a handful of NTP servers):
>
> 	refclock PPS /dev/cuaU1 local
>
> I don't expect amazing results given that USB is involved, but I'm not sure
> how to read the chronyc output to make sure that things are working.
> 'chronyc sources' lists the PPS source and it looks reasonable in general,
> but I'm not sure what the '?' source state means.  Is chrony using the
> source or is it ignoring it?
>
> MS Name/IP address         Stratum Poll Reach LastRx Last sample
> ===============================================================================
> #? PPS0                          0   4   377    13   -590ms[ -590ms] +/-   31us
> ^- kerberos.mit.edu              2   9   377   217   -171us[ -171us] +/-   25ms
> ^* time.cloudflare.com           3   8   377   917  -1018us[ -840us] +/- 8851us
> ...
>
> 'chronyc selectdata' is equally confusing - it looks like chrony correctly
> marked the source as unsynchronized but there appears to be no data.  Is
> that right?
>
> S Name/IP Address        Auth COpts EOpts Last Score     Interval  Leap
> =======================================================================
> s PPS0                      N ----- -----    0   1.0    +0ns    +0ns  ?
> D kerberos.mit.edu          N -P--- -P---  404   1.0   -19ms   +18ms  N
> * time.cloudflare.com       N -P--- -P--- 1103   1.0 -9124us +8298us  N
> ...
>
> This is my first attempt at using chrony, so I might be missing something
> obvious.
>
> Thanks,
>
> Jeff.
>
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