[ntp:questions] Packet timestamps when using Windows-7/Vista

David J Taylor david-taylor at blueyonder.delete-this-bit.and-this-part.co.uk.invalid
Fri Dec 11 20:57:50 UTC 2009

"Martin Burnicki" <martin.burnicki at meinberg.de> wrote in message 
news:s9u9v6-gj3.ln1 at gateway.py.meinberg.de...
> On the other hand, I've also seen systems where the interpolated time 
> steps
> back and forth by 1 ms, due to the time passed by Windows to the timer 
> callback steppingby 1 ms. I have *observed* this on XP, but I can 
> imagine
> this also happens on newer systems.
> Martin


I've added a test to my program to see whether the value from 
GetSystemTimeAsFileTime ever steps backwards, and it hasn't done so in my 
testing so far.  So I remain unsure why, on a system without the 
interpolation code, I'm seeing the TX time before the RX time.  Certainly 
would be nice to have someone confirm the result - a default installation 
on a Vista or Windows-7 should show this.


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