[time-nuts] NTP and Windows 7

David J Taylor david-taylor at blueyonder.co.uk
Thu Mar 27 12:07:31 EDT 2014

Greetings from Wales. I'm not sure whether this august forum is the
appropriate place to ask a question about PC timekeeping, but in the hope
that someone can point me in the right direction I'll ask anyway ;-)

I have just replaced Windows XP with Windows 7. The PC involved (a fairly
elderly 2.4GHz Core2 machine) runs an application called 'PlanePlotter'
which requires accurate timekeeping and mandates Meinberg's NTP software.
Using the UK pool.ntp.org servers as a reference source this has worked very
well under XP for several years and the clock was seldom more than a few
milliseconds out. Under Windows 7, however, the clock can be anything up to
0.2s awry and the offset is very erratic. The daily loopstats graph looks
like a section through a mountain range.

I have carefully checked all settings and combed the internet for
suggestions but can see no reason for the sharply degraded performance. Is
there something about Windows 7 that degrades the performance of NTP? Or is
there anything subtle I can check?

Many thanks in advance.



Two suggestions:

- stop NTP, delete the file etc\ntp.drift, and restart NTP.  Sometimes it 
can get a wild value for no obvious reason.

- be sure you are running the latest development version of NTP (4.2.7p434). 


At the back of my mind is a bug report suggesting using a poll interval of 
no greater than - possibly 7 - but the details aren't to hand.  Also 
power-saving may be running the clock at different rates at different times. 
Perhaps try disabling some of the power-saving options.

The only non-stratum-1 Windows 7 system I have here is Wi-Fi synced to a 
local stratum-1 server, and its performance is here:


It's currently working from a microADSB stick and uploading only, to Plane 

You cam also want to ask on the Usenet newsgroup, also accessible through 
Google groups:


SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 

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