[ntp:questions] Client using Meinberg NTP can't sync with ntp server problem

Martin Burnicki martin.burnicki at meinberg.de
Fri Jul 11 09:14:40 UTC 2014

Brian Inglis wrote:
> Never had a problem keeping within a few ms offset from UTC with
> only good network sources, Windows 7 x64, and NTP 4.2.6p5 stable.

As far as I have seen this may depend. On some systems it works, on 
others it doesn't which means the time synchronization doesn't settle.

I've seen systems where the residual offset and jitter reported by "ntpq 
-p" was continuously more than 1000 ms, and except for very rare cases 
where a problem with the mainboard or some other driver could be 
identified to cause these problems the resulting time accuracy could be 
increased to a few milliseconds or so after a developer version with the 
16 tick workaround had been installed, and the polling interval has been 

I'm not sure if the reason whether it works or not is whether the 
undisciplined system time runs fast or slow, in which case the time 
adjustment relative to the standard adjustment has to be decreased or 

This could cause different computations in ntpd's algorithms which 
compute the adjustment as well as in the Windows kernel which evaluates 
the adjustments.

> With the same platform plus a Garmin 18x LVC, stays within
> +/-60us offset, average +/-0.5us, s.d. < 15us;
> jitter < 50us, average < 20us, s.d. < 5us.

Haven't tried similar hardware refclock and eventually PPS under Windows 
myself, but I'd expect this works much better since AFAIK refclocks are 
in general polled in shorter intervals, at least in newer versions of ntpd.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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