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. Cheers! -Pete -- Pete Stephenson HeyPete.com _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
