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[time-freq] Query: Interest in clock synthesizer module -- useful for stabilizing PC timekeeping (among other things)

John Ackermann N8UR jra at febo.com
Sat Aug 19 18:10:38 UTC 2006


Mark Miller said the following on 08/19/2006 02:04 PM:

> I am glad that you mentioned that, it was a thought in the back of my
> mind.  That is why I am using REFLOCK II.
> 
> Replacing a PC clock is interesting too.  I have an NTP server that is
> disciplined by a Motorola Oncore, but this sounds like a suitable
> replacement and would not require any special software for GPS control.

Yeah, that's really the design goal.  By using a Clock-Block locked to
an external reference, you can reduce the NTP drift rate to
approximately 0ppm -- of course, how "approximately" depends on the
reference.  You'll still need something external to set the "on time"
point, but once it's set, it'll stay (more or less) put.

I have about five NTP stratum 1 servers in the basement tied to GPS,
GPSDO, WWVB, and Cesium, but even with them it's hard to get good
timekeeping using the undisciplined PC clock -- if one of the servers
happens to switch references or lose lock, you see the offset
immediately.  I'm not sure I'll get around to using a Clock-Block on all
of them, but at least my master that monitors the others will get one.

73,
John




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