[ntp:questions] Idea to improve ntpd accuracy

Charles Elliott 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?

Charles Elliott

-----Original Message-----
From: questions
[mailto:questions-bounces+elliott.ch=comcast.net at lists.ntp.org] On Behalf Of
Hal Murray
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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