[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.
RGDS
GARY
---------------------------------------------------------------------------
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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