| Re: [chrony-users] help - UTC time of PPS pulses |
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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] help - UTC time of PPS pulses
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Tue, 13 Oct 2020 12:29:31 +0200
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On Tue, Oct 13, 2020 at 10:03:10AM +0000, Yoed Stavi wrote:
> Hi,
>
> I use Chrony as our NTP client and also for PPS synchronization.
> This works great.
> The same server creates a DVB-T transport (MPEG-2 TS with MIP packets). The DVB-T protocol includes timestamps that should be relative to GPS pulses.
> Since the DVB-T software doesn't know when the GPS pulses are (only Chrony knows that), I set the timestamps to be relative to whole UTC seconds instead of GPS pulses.
>
> I would like to improve by knowing the offset between GPS pulses and UTC seconds as it is measured by Chrony (from my measurements the result should be between 230-250 milliseconds).
I'm not sure if I understand your goal correctly. You have chronyd
configured to synchronize the system clock to UTC using a PPS signal
coming from a GPS receiver and you want to measure the offset between
the PPS and UTC? That would be the offset that chronyd is minimizing,
i.e. it should be close to zero. The measurements can be reported by
the "chronyc sources" command, and also in the refclocks log if
enabled.
--
Miroslav Lichvar
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