| Re: [chrony-users] Chrony configuration with GPS+direct PHC |
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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] Chrony configuration with GPS+direct PHC
- From: "Kevin P. Fleming" <kevin@xxxxxxx>
- Date: Mon, 24 May 2021 06:32:46 -0400
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On Fri, May 21, 2021 at 3:11 AM Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
>
> If you could set the pulse width to 500 ms (width 0.5) that would
> maximize the PPS locking range. With the 100ms width you will probably
> need to find a closer NTP server and/or set the precision/delay of the
> SHM refclock to a smaller value and correct its offset.
Thanks! That made a big difference :-) With the pulse width in the
receiver set to 500ms, and the chrony configuration:
refclock SHM 0 refid GPS precision 1e-1 offset 0.065
refclock PHC /dev/ptp3:extpps:nocrossts refid PPS width 0.5 precision 1e-7
Chrony is quite happy with the PPS refclock now, but not so happy with
the GPS refclock; I'll have to discuss that with the gpsd team.
root@edge21-b:~# chronyc sources
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#- GPS 0 4 377 13 -3989us[-4040us] +/- 100ms
#* PPS 0 4 377 8 +23ms[ +23ms] +/- 17ms
^- linode1.ernest-doss.org 3 10 173 292 -29ms[ -29ms] +/- 65ms
^+ dynamic-75-76-123-222.kn> 2 10 377 179 -27ms[ -27ms] +/- 57ms
^+ voipmonitor.wci.com 2 10 377 12 -25ms[ -25ms] +/- 45ms
^- 216.228.192.52 3 10 377 21 -32ms[ -32ms] +/- 155ms
root@edge21-b:~# chronyc sourcestats
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
GPS 10 6 143 -16.475 87.303 -3134us 2502us
PPS 6 4 81 +0.015 0.127 +23ms 940ns
linode1.ernest-doss.org 6 4 103m +0.111 0.505 -29ms 274us
dynamic-75-76-123-222.kn> 11 5 172m -0.326 0.325 -31ms 758us
voipmonitor.wci.com 7 5 103m +0.243 0.739 -25ms 524us
216.228.192.52 10 7 154m +0.005 0.071 -32ms 145us
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