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Re: Using gpsfake with Chrony
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From: |
Gary E. Miller |
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Subject: |
Re: Using gpsfake with Chrony |
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Date: |
Mon, 10 Feb 2020 11:35:02 -0800 |
Yo Simon!
On Mon, 10 Feb 2020 13:10:42 +0100
Simon Larsen <address@hidden> wrote:
> So my question is the following: Is it possible to replay an NMEA
> logfile through gpsfake and have GPSD process/send the data to
> Chrony? Kind regards, Simon Larsen
Yes, but pointless. The timing info that chronyd needs is the PPS,
and the PPS data is not in the NMEA. There is some coarse timing in
the NMEA, but unless it is played back with precise timing then it
will just confuse the filters in chronyd/ntpd.
You will need to capture the SHM() data, the data gpsd sends to chronyd,
and play it back exactly so that chronyd see it with relative timing
intact.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
address@hidden Tel:+1 541 382 8588
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"If you can't measure it, you can't improve it." - Lord Kelvin
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