Hi For further info on just why the crystal temperature is such a crazy thing to track, check out Rick’s paper. At first glance it *seems* like it’s a trivial thing. In reality, gradients are a very big deal.
Bob > On Jun 5, 2017, at 6:38 PM, Charles Steinmetz <csteinm...@yandex.com> wrote: > > Chris wrote: > >> Today all you need is a reliable way to measure the error >> between the crystals' current temperature and the set point. > > That's all that's ever been needed. But it is devilishly difficult to > measure the actual quartz temperature, or even to find a good proxy that is > easier to measure. > > There is a fair body of published research on these topics, including Rick's > (et al.) work on zero-gradient ovens. > > Keep this in mind when someone says they are controlling the "oven > temperature" to 0.001C (or even 0.1C). They are measuring *something*, and > may even be holding whatever it is "constant" within fairly tight tolerances. > But they have no idea what the quartz temperature is, and no way to know > with precision the relationship between the measured temperature and the > actual quartz temperature. > > Some years ago, I consulted for a research group that was using a number of > non-contact technologies to measure the temperature of oscillating quartz > crystals. The results were promising, but there were some issues with > measuring the temperature (which is, essentially, quantifying tiny random > molecular motions within the crystal lattice) against the background of the > hugely greater macro motion of the vibating quartz. I never knew the final > conclusions, nor am I aware of any systems designed using these principles or > methods. But it is something to think about if you *really* want a > temperature-stable oscillator. > > Best regards, > > Charles > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
