Re: [chrony-users] Chrony gets out of sync regularly

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On Tue, Mar 01, 2022 at 03:09:27PM -0600, Steven Sommars wrote:
> I understand the jumps to be gpsd-related.    I see identical behavior on
> one of my RPi4+ublox GPS units.
> NMEA sentence timing remains consistent.     As an optimization some gpsd
> versions move the GPS into ublox binary mode for the serial data stream.
>  The ublox serial binary mode timing is not consistent.  The gpsd folks
> apparently believe that the arrival time of serial data is untrustworthy
> and should not be used.

Can you try the following command and compare the output when the
offset jumps?

# gpspipe -T '%s' --usec -r | sed 's|,.*||'

For example, with gpsd 3.23.1 and a ublox unit I have here I get:

1646208470.067774: $GPZDA
1646208470.067792: $GPGGA
1646208470.067806: $GPRMC
1646208470.067811: $GPGSA
1646208470.067814: $GPGBS
1646208470.082703: $GPGSV
1646208470.082721: $GPGSV
1646208470.082726: $GPGSV

The timing of the messages in my case is stable to about 20
milliseconds. In the "super-raw" (gpspipe -R) output I can see it's
using the binary protocol.

Miroslav Lichvar

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