William Unruh wrote:
On 2014-12-09, Charles Swiger <cswi...@mac.com> wrote:
...
[ ... ]
Of course, in an ideal system designed for clock stability, the clock
variation with temperature would be measured, and an offset based on
the temperature of the crystal applied directly to the output of the
clock itself, before it was supplied to the operating system.
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.
The correct solution is of course to not depend on $0.10 crystals as the
time base for dedicated NTP servers. :-)
Terje
--
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"
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