Re: [chrony-users] Not getting time from gpsd

Ok I set it to 0.0065 offset. Here's my chrony.conf

pool pool.ntp.org
driftfile /var/lib/chrony/drift
allow
refclock SHM 0 refid GPS offset 0.065
#refclock SHM 0 refid GPS precision 1e-1 offset 0.9999 delay 0.2
makestep 1 -1

and here is the chrony sources output:

irishmistii@IrishMistII:~ $ chronyc sources
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 12 +2112us[+2967us] +/- 325us
^- orchid.sidereal.ca 2 6 17 19 +11ms[ +12ms] +/- 40ms
^- static-96-244-96-19.bltmm 2 6 17 19 +11ms[ +12ms] +/- 40ms
^- hydrogen.constant.com 2 6 17 18 +14ms[ +15ms] +/- 32ms
^- host2.kingrst.com 2 6 15 19 +9078us[ +10ms] +/- 100ms
irishmistii@IrishMistII:~ $ chronyc sources
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 9 +132us[ +236us] +/- 339us
^- orchid.sidereal.ca 2 6 17 50 +9849us[ +12ms] +/- 40ms
^- static-96-244-96-19.bltmm 2 6 17 51 +9227us[ +12ms] +/- 40ms
^- hydrogen.constant.com 2 6 17 50 +13ms[ +15ms] +/- 32ms
^- host2.kingrst.com 2 6 15 51 +7529us[ +10ms] +/- 100ms
irishmistii@IrishMistII:~ $ chronyc sources
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 9 +2596us[+3043us] +/- 464us
^- orchid.sidereal.ca 2 6 37 13 +14ms[ +14ms] +/- 39ms
^- static-96-244-96-19.bltmm 2 6 37 13 +9722us[ +10ms] +/- 44ms
^- hydrogen.constant.com 2 6 37 13 +14ms[ +14ms] +/- 33ms
^- host2.kingrst.com 2 6 15 78 +6938us[ +10ms] +/- 100ms

On Tue, Aug 9, 2016 at 9:25 AM, Bill Unruh <unruh@xxxxxxxxxxxxxx> wrote:

So GPS is what the system is using to set the time. clockb.ntpis.org is not
responding at all. The other three have responded three times, and have not
been queried again during the very brief time you have make these tests. They claim that your system time is out by about 60-70ms so you might want to use
that as an offset for the GPS clock.

I have no idea why clockb is claiming to be stratum 0 except that that is
probably the default stratum if the remote clock is unreachable. I would have
thought 15 was a more reasonable value for that, but....

On Tue, 9 Aug 2016, Chris Greenman wrote:

Ok I took out the offset, precision, and delay. I let everything stabilize a bit and then took 3 samples.
Here's what it came up with.
$ date && chronyc sources
Tue 9 Aug 08:54:52 EDT 2016
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 15 +1479us[+1575us] +/- 522us
^? clockb.ntpjs.org 0 6 0 - +0ns[ +0ns] +/- 0ns
^- proxmox.undeadarmy.com 2 6 7 8 -63ms[ -63ms] +/- 87ms
^- host2.kingrst.com 2 6 7 9 -72ms[ -72ms] +/- 91ms
^- clock.xmission.com 1 6 7 8 -65ms[ -65ms] +/- 41ms

irishmistii@IrishMistII:~ $ date && chronyc sources
Tue 9 Aug 08:55:00 EDT 2016
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 12 -606us[-1568us] +/- 422us
^? clockb.ntpjs.org 0 6 0 - +0ns[ +0ns] +/- 0ns
^- proxmox.undeadarmy.com 2 6 7 16 -62ms[ -63ms] +/- 87ms
^- host2.kingrst.com 2 6 7 16 -71ms[ -72ms] +/- 91ms
^- clock.xmission.com 1 6 7 16 -64ms[ -65ms] +/- 41ms

irishmistii@IrishMistII:~ $ date && chronyc sources
Tue 9 Aug 08:55:08 EDT 2016
210 Number of sources = 5
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#* GPS 0 4 377 20 -606us[-1568us] +/- 422us
^? clockb.ntpjs.org 0 6 0 - +0ns[ +0ns] +/- 0ns
^- proxmox.undeadarmy.com 2 6 7 24 -62ms[ -63ms] +/- 87ms
^- host2.kingrst.com 2 6 7 25 -71ms[ -72ms] +/- 91ms
^- clock.xmission.com 1 6 7 24 -64ms[ -65ms] +/- 41ms

On Tue, Aug 9, 2016 at 8:10 AM, Chris Greenman <chris.m.greenman@xxxxxxxxx> wrote:

Thanks. I already enabled my NTP sources and you're right, the gps is getting marked as bad.
I'll play with that today.

Chris

On Aug 9, 2016 4:42 AM, "Miroslav Lichvar" <mlichvar@xxxxxxxxxx> wrote:
On Mon, Aug 08, 2016 at 01:21:56PM -0400, Chris Greenman wrote:
> 210 Number of sources = 1
> MS Name/IP address Stratum Poll Reach LastRx Last sample
>
> ===============================================================================
> #* GPS 0 4 377 17 +296us[ +347us] +/-
> 200ms
>
>
> I am perfectly happy with 200ms error in time. That more than suits my
> needs.

You might want to try this with some NTP sources and see how accurate
is the GPS time source. From that you would adjust the offset value on
the refclock SHM line so the the error is reduced and the GPS source
is not marked as a falseticker when there are other source. I'd also
suggest to add "minsamples 64" to the refclock directive, so chronyd
doesn't try to follow short-term variations in the measured offset
(the error in the message based GPS time tends to be non-random).

--
Miroslav Lichvar

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