[ntp:questions] help with setting up NTP on windows with a USB GPS

David J Taylor david-taylor at blueyonder.not-this-bit.nor-this-part.co.uk.invalid
Mon Nov 30 15:51:26 UTC 2009

"jack" <> wrote in message 
news:7cc021d3-4ca9-47b3-8ab8-7aa00424389d at h10g2000vbm.googlegroups.com...
> Thank you, David. You're very helpful!
> I ran both my setups over the weekend. The GPS with 1PPS has the worst
> offset of 200us and the GPS without jumped up to 80ms, clearly due to
> loss of satellite signals. I am happy with the performance of the GPS
> with 1PPS out.
> RGB: I have a similar PCI-serial card in my computer. I will try my
> GPS with this board and let you know the results.
> Jack

The 80ms could have been due to all sorts of things, particularly with 
Windows Vista or Windows-7 with certain peripherals, but with the Windows 
XP you are running it should be reasonably free from odd effects. 
Certainly, without PPS a pure serial GPS may be no better than using a LAN 
server.  My own XP/GPS/PPS system is usually well within 250us, as you can 
see here:


That's with a GPS on the roof of the house with a view of about half the 


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