[ntp:questions] Installing more stable oscillator?

Pete Stephenson pete+usenet at heypete.com
Fri Jul 13 07:24:13 UTC 2007

After a few days of running with good sync to internet servers, my test 
server's system clock shows a drift of about -27ppm, which seems to be 
pretty reasonable for a cheap crystal oscillator.

However, I occasionally see people in this newsgroup discussing various 
alternative oscillators, like oven-stabilized crystals, rubidium and 
cesium frequency standards, and even hydrogen masers.

Obviously, many of these options are far too large to simply replace the 
computer's hardware oscillators. How, then, are these oscillators used 
with NTP servers?

Is it possible to have NTP completely ignore the computer's crystal 
oscillator and use an external oscillator? For example, can one have a 
GPS reference clock sending the time and a PPS signal to discipline an 
external rubidium oscillator (or oven-stabilized crystal, or cesium, or 
whatever), which is then used to supply time to other systems via NTP?

I'd imagine that such a setup would be significantly more stable than 
the cheap crystal oscillators put in most computers these days, 
particularly if the reference time source(s) were somehow interrupted 
and the oscillator had to freewheel for an period of time.

With used rubidium standards available for 
reasonable-to-the-dedicated-hobbyist prices on eBay, this is something 
that's crossed my mind as an interesting thing to do...sort of a "gee, 
wouldn't it be fun to have a /real/ atomic clock in your apartment?" 
type thing.


Pete Stephenson

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