| Re: [chrony-users] Improving local clock error |
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On Tue, Dec 11, 2018 at 01:49:52PM +0000, STR . wrote:
> Hi,
>
> I see a constant ~15 ppm error in my local clock graphs using an
> Uputronics uBlox MAX-M8Q GPS.
> chrony-graph - https://imgur.com/a/efCFh2k
>
> How do I improve this, set 'maxclockerror' to 10 or 13 ppm?
I think that's just the "Frequency" value from the tracking log. It's
the error of the clock source that's used as the system clock (e.g.
TSC). It doesn't matter how large it is, because it is compensated by
chronyd.
What matters is stability. So, an improvement would be to make it more
stable, but that's difficult. The temperature of the crystal would
need to be stabilized (e.g. blow the heat from the CPU away), or at
least accurately measured and compensated using the tempcomp
directive.
--
Miroslav Lichvar
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