[ntp:questions] Re: NTP server with Rubidium PPS

Mauro Fiacco Mauro.Fiacco at ipaccess.com
Tue Oct 11 12:27:31 UTC 2005


Maarten,

thank you for your answer. 

I understand that my NTP client should not synchronise to an offset
larger than the threshold. However, Rubidium sources are often
un-synchronised... They only offer a frequency correction signal!

I was expecting to be able to use a fudge factor (time1) in order tell
ntpd the offset of my pps source... but without much success.

I use "iburst" on my timeservers, and although I have not tested without
it, I expect that the results is to calculate the inital offset very
quickly (as you suggested). But as the offset is very large... the
server won't synchronise to any of the timeservers (yes... I did used
the "prefer" keyword!).

Thank you again!

Mauro


On Tue, Oct 11, 2005 at 01:32:43PM +0200, Maarten Wiltink wrote:
> Date: Tue, 11 Oct 2005 13:32:43 +0200
> From: Maarten Wiltink <maarten at kittensandcats.net>
> To: questions at lists.ntp.isc.org
> Subject: [ntp:questions] Re: NTP server with Rubidium PPS

> "Mauro Fiacco" <Mauro.Fiacco at ipaccess.com> wrote in message
> news:20051011104209.GB10986 at ipaccess.com...
> [...]
> > The only way I seem to be able to obtain synchronisation _and_ PPS is
> > to turn on a off my PPS source until the offset is below the critical
> > 128ms... Which takes too much time!!!

> 128ms is the step threshold. If your offset is larger than that, you
> are by definition not synchronised, even if you did qualify for the
> FLL stage of synchronisation (correct clock _speed_ only, ready to
> start getting the top of the second right). I leave the consequences
> of that to your imagination.

> Try adding the "iburst" option to those higher stratum servers. After
> the step that _should_ be forced by being over 128ms out (but your
> message was strangely quiet on that subject), an "initial burst" (and
> initial only, please) would get you into a synchronised state much
> sooner.

> Groetjes,
> Maarten Wiltink


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-- 
Mauro Fiacco 

ip.access Ltd                      
URL: www.ipaccess.com  




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