[ntp:questions] NTP server with Rubidium PPS

Mauro Fiacco Mauro.Fiacco at ipaccess.com
Tue Oct 11 10:42:09 UTC 2005

Hi all,

I have a strange problem which I would like to share (and may find a

We have a Rubidium source which we use as PPS for our NTP server (running
freeBSD 5.4, ntpd 4.2.0 - standard ports)

My NTP server is also configured to use a number of high stratum NTP
servers as timeservers.

I have been experimenting with this settings for quite long time and I
come to the conclusion that if the offset of the PPS (which is
unsynchronised) is greater than 128ms respect to the offset of the
timeservers, won't allow ntpd to step it's time and reduce the offset.

Am I correct? 

I have tried to use the tinker configuration word in my conf file
(tinker step 0.512) without success.

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!!!

Any ideas on how best use the PPS signal?

Thank you in advance.



Mauro Fiacco 

ip.access Ltd                      
URL: www.ipaccess.com  

More information about the questions mailing list