On Dec 9, 2014, at 2:41 AM, Terje Mathisen <terje.mathi...@tmsw.no> wrote: [ ... ] >>> Yes; you're describing calibrating a temperature-compensated XO, or TCXO. >> >> There are also versions of ntp which have a temp >> compensation/measurement system compiled in to apply to the clocks. It >> does tend to give much better control of the clock than regular ntpd >> apparently. > > It does help: > > On motherboards with a temperature sensor close to the master crystal, you > can get somewhere in the 2-10x range improvement in the size of temperature > excursions.
I'd agree with this, although the best case is probably not quite an order of magnitude, more like a factor of 5x. Or perhaps I shouldn't be too optimistic about how bad a really cheap crystal can be. :-) > The correct solution is of course to not depend on $0.10 crystals as the time > base for dedicated NTP servers. :-) Well, yes. You can get a PCI(e) card with a TCXO or OCXO and an optional GPS module like the Beagle ClockCard or a SpectraCom TSync for a few hundred bucks. That's quite a bit more than a $40 GPS puck, but these will also freewheel for a lot longer before losing or gaining a second in error: ~2 seconds/month if kept stable at 23C, I believe one said. Regards, -- -Chuck _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
