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

Richard B. gilbert rgilbert88 at comcast.net
Sat Apr 7 14:04:31 UTC 2007

Eugen COCA wrote:
> 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.
> Hal,
> 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 ?

I don't believe that more than one "prefer" keyword is useful.  ISTR 
reading here that ONLY ONE source can be "preferred".

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