[ntp:questions] how do I lock in average frequency correction

David J Taylor david-taylor at blueyonder.co.uk.invalid
Mon Feb 13 08:50:27 UTC 2012

"Dave Hart" <hart at ntp.org> wrote in message 
> Sad fact:  No matter how well ntpd is able to discipline the clock on
> Windows, other apps are generally stuck with a low-precision system
> clock.  It may be sync'd to within less than 100 usec to UTC, but when
> apps read the clock using Windows APIs, it's truncated to a precision
> between 0.5 and 15.6 msec.  Higher resolution clock reading means
> requiring ntpd be running and querying it in SNTP fashion.
> Cheers,
> Dave Hart

Another approach to obtaining more precise timestamps under Windows XP is 
given here:


and can be used whether NTP is running or not.  With NTP running it can be 
both more precise and more accurate.  I played with this using both TSC 
and QPC (Query Performance Counter) implemented in Delphi and it seemed to 
work as advertised.


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