Yo Hal! On Thu, 28 Jul 2016 17:26:40 -0700 Hal Murray <[email protected]> wrote:
> [email protected] 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 [email protected] Tel:+1 541 382 8588
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