[ntp:questions] What level of timesynch error is typical on Win XP?

David J Taylor david-taylor at blueyonder.co.uk.invalid
Thu Oct 21 15:07:22 UTC 2010

> The platforms in question are running Windows XP, not Vista or Windows
> 7.  How does this change the answer?

NTP will switch on the multi-media timers in Windows XP and achieve the 
best performance I have seen on Windows systems.  Temperature (or perhaps 
CPU load causing temperature change in your case) seems to be the limiting 
factor in the peak offset.

> By the way, the hardware is a collection of 8-core HP Z800 workstations
> connected together by copper gigabit ethernet links and local hub, with
> one link going via the company network to the GPS network time server.
> Joe Gwinn

Beware the 1Gb/s adapter settings, as Dave Hart mentioned.  You may find 
you get better timekeeping performance setting them to 100Mb/s.

You might consider providing a local, more precise NTP server with 
something like a small, fan-less Intel Atom system running FreeBSD and 
synched across the network to your GPS time server.  You might be able to 
keep a small box like that in a more temperature controlled environment, 
but even without it might provide a way of smoothing out any jitter due to 
your remote connection to the GPS server.

Another thought is to send 1PPS across the network (an old RS-232 link, 
perhaps, just used as a direct connection, not for serial data), and 
duplicate the PPS feed to your remote server locally.  Then make an RS-232 
level driver to send PPS to all your workstations.  They get the precise 
seconds from the PPS, and the nearest-second time from the network.


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