[ntp:questions] Idea to improve ntpd accuracy
elliott.ch at comcast.net
Sun Feb 28 21:16:10 UTC 2016
Thank you very much for the paper reference on temperature compensation.
The paper and its results are excellent. A self-calibration feature (that
worked) so that each user could have it configured for his/her own computer
should not be too hard to implement. I wonder why NTPD never picked it up?
[mailto:questions-bounces+elliott.ch=comcast.net at lists.ntp.org] On Behalf Of
Sent: Saturday, February 27, 2016 11:19 PM
To: questions at lists.ntp.org
Cc: Hal Murray
Subject: Re: [ntp:questions] Idea to improve ntpd accuracy
> I thought of that too but rejected it as way too machine-specific.
> Because the clock PLL does not track frequency ramps feed-forward
> could be very effective (e.g. order of magnitude). To make this work
> however, you need to first discover which one of many potential
> temperature sensors on the MB are most closely correlated with
> frequency, then measure a rough linear gain from temperature to PPM.
> Seemed too hardware-instance-specific to me, but perhaps there's a way...
You want to measure the temperature of the crystal.
Several/many years ago, Linux used to use the RTC/TOY clock for the main
timekeeping. Now, the main CPU clock is used. You want to get a temperate
probe on that.
Mark Martinec has a wonderful web page on that.
NTP temperature compensation
These are my opinions. I hate spam.
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