[ntp:questions] Problem with system clock refresh

David J Taylor david-taylor at blueyonder.not-this-bit.nor-this-part.co.uk.invalid
Mon Nov 23 16:54:22 UTC 2009

"JuanFran" <juanfranciscojara at gmail.com> wrote in message 
news:a26c31ce-d0bc-4fa2-a93b-d6c663a94572 at j9g2000vbp.googlegroups.com...
> Hello! I work in a project that it need synchronize a LAN for collect
> data and images in real time. I need a lot of precision in the
> synchronization of all computers on my LAN.
> Thanks for your answer! I will try your solutions
> Regars!

What precision do you want?

I have some plots of what I see on my Windows systems here:


I have three stratum-1 servers based on Windows-2000 (Bacchus), Windows-XP 
(Feenix) and Windows-7 (Stamsund) all driven from Garmin GPS 18 LVC 
devices.  If you needed a better stratum-1 server I would recommend a 
FreeBSD-based system.

One Windows-XP system is synched to two of those stratum-1 servers, and 
that is the PC Narvik.  You can see that it keeps within about 3ms of the 
correct time, and the offset has a strong periodic component because of 
the temperature variations in this "domestic" environment.

If within 3ms isn't good enough, one approach might be to get a GPS 18LVC 
or other GPS receiver with a PPS (pulse per second) output, and building a 
box which would drive all the PCs you need with an RS232 signal derived 
from the PPS source.


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