[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

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:

  http://www.satsignal.eu/mrtg/alta-ntp-b.html

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:

  http://www.satsignal.eu/mrtg/stamsund_ntp_2.html

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.

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



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