NEO-6M PPS jitter

David Mikolajczyk mikolajczyk.david at
Tue Jun 11 10:15:31 UTC 2019

> On Jun 11, 2019, at 01:36, Hal Murray <hmurray at> wrote:
> mikolajczyk.david at said:
>> server maxpoll 0 minpoll 0 prefer
>> server maxpoll 0 minpoll 0 noselect 
> Where did you get the idea for such a low polling?
> There is a filter on refclocks that discards outliers and averages the rest.  
> You have disabled that.

I got it from the GPSD Time Service HOWTO [ ].  It says:

"ntpd seems to better use a PPS refclock when the polling interval is as small as possible. The ntpd default minpoll is 6, and can be set to as low as 4. NTPsec versions 0.9.5 and above of ntpd allow you to set minpoll and maxpoll as low as 0. Changing minpoll from 4 to 0 may reduce your PPS jitter by over a factor of 4.”

I will remove the maxpoll and minpoll directives from my ntp.conf and see how things go without them.


David Mikolajczyk

More information about the users mailing list