[ntp:questions] GPS and the December 5/6 Solar Flare

Eugen COCA ecoca at eed.usv.ro
Sat Apr 7 10:49:58 UTC 2007

On Apr 7, 10:36 am, hal-use... at ip-64-139-1-69.sjc.megapath.net (Hal
Murray) wrote:
> >I still have a question unanswered: are there any method to pass over
> >a long GPS failure (say for several days or more) - supposing the GPS
> >is the
> >only source of time and the server have a very good (10E-12) PPS
> >source (Rubidium or Caesium) ?
> Google for Z3801A.  It's basically a box with a very good crystal
> oscillator, a GPS receiver, and a pile of software.  If the GPS
> goes down, it coasts on the crystal.
> How long you can coast depends upon how good your clock is and/or
> your accuracy requirements.


I have the GPS receiver (many), I have the Rubidium standard (many),
I have a PC with FreeBSD (or any other good OS needed) and, of course,
we all have NTPD.
My questions was how can I make this system to depend as little as
possible on the GPS signal.

I exposed a solution - by the two "prefer" kewords. This is a good
solution as the drift after
four days was negligible (<1E-6).

Other opinions on this configuration ?

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