[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
news:CAMbSiYDUXf3g4qk_ng2xcgu70=RxMqyrFj-35qMmAU6-
[]
> 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:
http://www.lochan.org/2005/keith-cl/useful/win32time.html
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.
Cheers,
David
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