[ntp:hackers] Windows-7 64-bit performance (was: Re: Reduce jitter of refclocks (connected via USB))

David J Taylor david-taylor at blueyonder.co.uk
Tue Mar 15 17:48:47 UTC 2011

> Anyway, it seems like the achievable jitter figure depends a lot on the 
> specific Windows/driver version combo, I'm getting 1-2 ms jitter from 
> the Sure GPS board connected to a real COM1 port on W7-64. :-(
> Terje


I tested NTP with the Sure board on a Windows-7 64-bit system for several 
hours today, and I could see no difference:


The actual period was from about 09:30 to just after 15:00 UTC.  This is 
very much at odds with the behaviour I see on a similar 32-bit system:


and makes me wonder whether the QPC interpolation of the PPS edge is 
working correctly.  Admittedly, the 32-bit system does have Dave Hart's 
excellent serialPPS.sys driver (lacking on the 64-bit system because it's 
not signed), so I may test the 32-bit system without the Atom driver to 
see how it affects things.

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

More information about the hackers mailing list