Re: [gpsd-dev] Disturbing numbers

[Greg Troxel]

Andy Walls <address@hidden> writes:

> Sounds reasonable for startup.  I wouldn't expect it at steady/stable
> state.
>
> ntpd prefers to slew clocks into alignment.
>
> system clock frequency will change, and ntpd will have to adjust it, a
> bit until your computer is thermally stable.
>
> Do keep in mind, that compared to a decent PPS, it is the ntpd
> disciplined system clock which is drifting.

All true, and I don't mean to contradict Andy

What I'd expect is that because the frequency error estimate that NTP
uses ("drift") isn't right when you first start NTP, there will be a
phase error that persists while the frequency is estimated.  So if your
clock is a litle slow, then it will keep getting behind, and the
positive offset will cause NTP to adjust the phase forward and also
increase the frequency offset error.  After a day or so or maybe less
the frequency estimate will be very close and there won't be a
persistent offset.  This is all normal.

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