I should have been a bit clearer.  I am checking when
I sync up the time.  At that point the PC clock should
be  pretty close.  Maybe I should have just omitted
the PC clock part from the question.

--- Olin Lathrop <olin_piclist@embedinc.com> wrote:
> phil B wrote:
> > I compare it
> > against my PC clock which I sync up against the
> atomic
> > clock every day.
> >
> > What I'm seeing is that the two clocks are not off
> by
> > a constant amount but drift around by as much as
> 30
> > seconds + or - in a day.
> 
> PC clocks are not a good reference, even if they are
> supposedly synchronized
> to the time standard periodically.  I've seen 10s of
> seconds off, depending
> on when synchronization was done.  I think the
> algorithm tried to adjust the
> PC clock smoothly, so it may not be that close even
> if it recently checked
> the time standard.
> 
> Manually check your RTC against a known time
> standard and see if the issue
> goes away.
> 
> 
>
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