[ntp:questions] Local time sources
jwinius at umrk.nl
Mon May 10 19:14:22 UTC 2010
On Mon, 10 May 2010 07:58:37 +0100, David J Taylor wrote:
> I suspect that depends on the precision required. If you /need/ the
> precision which the GPS provides, and an inaccurate time is
> unacceptable, then add no other sources. If serving time at a reduced
> accuracy is acceptable, add four or five external servers for
> redundancy. In addition to redundancy, another advantage might be that
> you get a check that you aren't working on the wrong edge of the GPS
> pulse, by looking at the output of ntpq -p, and seeing that the offset
> of the backup sources is reasonable.
Okay, I think this answers my question. I've been running a Garmin GPS 18
LVC for a few years now...
What this page does not say is that my configuration also includes a
DFC77 receiver. This long-wave radio time signal receiver is an order of
magnitude less precise than the GPS receiver, but it has already proved
its value several times in terms of redundancy: twice when the GPS fell
from the skylight following a suction-cup failure, and once when gpsd
failed to function properly after an update. That's great, but the point
is that there's not much else to it.
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