[time-nuts] Histogram of T2 arrival times

Gary E. Miller gem at rellim.com
Thu Jul 28 20:46:29 EDT 2016

Yo Hal!

On Thu, 28 Jul 2016 17:26:40 -0700
Hal Murray <hmurray at megapathdsl.net> wrote:

> gem at rellim.com said:
> >> The systems collecting the data have 200-300 microsec peak-peak of
> >> clock offset, mostly tracking daily temperature swings.  
> > How do you know that?   
> Which "that"?

The thing just previous to "that": temp swings.

> You can get the temperature connection by plotting offset and
> temperature over 24-48 hours.  You can get confirmation by plotting
> the drift.

So, you have plotted offset versus temp?  Can we see that?

> Crystals are well known to have a temperature effect so the
> drift-temp connection shouldn't be surprising.

I would not be surprised if temp was dominant here.  But I can think
of a few other things that may be dominant instead.

If you have data, I'd love to see it, but conjecture is not very
useful, except to design a new experiment.

> On Linux, you can get the temperature from
>   /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
> or similar. 

I would only consider CPU temp a very rough proxy for XTAL temp.  Room  
ambient would be much closer to XTAL temp.

> You would really like to measure the temperature at the crystal.  I
> haven't gone that far.

Yup.  I have some USB thermometers that are good for such things.

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588
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