[ntp:questions] ***SPAM*** Re: HowTo calibrate system clock frequency using NTP

Wolfgang S. Rupprecht wolfgang+gnus20060202T002731 at dailyplanet.dontspam.wsrcc.com
Thu Feb 2 08:37:12 UTC 2006

"Richard B. Gilbert" <rgilbert88 at comcast.net> writes:
> If you want to make a one-time correction to your clock frequency, 500
> ms/day may be a reasonable objective.   As Terje pointed out, the
> frequency varies with temperature and the temperature varies with the
> time of day, season of the year, whether the heat is on or off, etc.
> The frequency will also change, slowly, as the crystal ages.

Modern motherboards all seem to have the ability to read the ambient
temperature.  It might be possible to null out some of the temperature
variation of the xtal by generating a table of ppm-offset vs. reported
temperature while ntpd is running.  Then when the system runs open
loop at some later time, some fairly simple hack can load different
ppm corrections depending on the reported temperature.

Wolfgang S. Rupprecht                http://www.wsrcc.com/wolfgang/
Direct SIP URL Dialing: http://www.wsrcc.com/wolfgang/phonedirectory.html

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