[time-nuts] temperature sensor
Tom Van Baak
tvb at LeapSecond.com
Mon Jul 21 02:18:38 EDT 2014
> What I am missing in all these discussions is what do we want to archive
> or is this an other paper only discussion. I am used to starting out with a
> goal, and tackle the challenge from there.
> We have a saying in German "Papier ist geduldig. Translate You can write
> any thing on paper.
> Bert Kehren
Let me answer in two parts.
1) The issue of precision temperature sensing is so key to the field of precise time & frequency that any thread that attracts more information, anecdotes, and wisdom from the group is very welcome. Quartz is such an amazing substance that its use as a precision sensor is every bit as interesting as its use as a precision timekeeper.
Not everything has to be goal oriented. Some discussions on this list are pure enjoyment, others highly educational, and some simply plant seeds. Starting with concrete goals is good for a business but when working with precision timing as a hobby, as most of us are, goals are sometimes secondary to just learning or playing around.
2) If you want an example of a specific goal related to temperature, try this:
There have been several discussions over the years about variable fan speed based temperature control. I can't explain it, but I've always been suspicious of this technique. It seems to me still air is inherently better than moving air. Passive (no fan) is better than active (fan). And constant velocity is better than turbulence is better than variable velocity. But I don't know for sure. That's where experiments and measurement come in.
To satisfy my curiosity and get actual data I'd like to place 6 or more tiny analog high-resolution temperature sensors all around the OCXO of a Trimble Thunderbolt. That's high-resolution both in temperature and in time. In other words, no fake accuracy "averaging" allowed. The goal is to observe thermal gradients in real-time and see how good, or how bad, the correlation is among crystal temperature, case temperature, and DS1620 temperature sensor (which is mounted a considerable distance from the OCXO). The same technique, and maybe even the same conclusions, might apply to Rb.
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