>> I think that I would start by looking at 32kHz watch crystals, I've >> often wondered how good a timebase you can make out of one. The tempco >> is a parabola around 25C with a max slope of something like 0.05 PPM/C, >> so they are naturally a pretty good timebase with good aging >> characteristics. The crystals are really tiny, maybe insulating it with >> a material that has an interesting heat of fusion along with a micro to >> model the physics of the parabolic shape of the crystal performance. >> >> jeff >> >> > Maybe an ensemble of watch crystal clocks and a PIC microprocessor per > David Allan paper > of some years ago. After testing you could assign deferent weighting to > the different clocks. > > Bill K7NOM >
Yes, an ensemble of 32kHz crystals, I like it a lot. Perhaps you can setup a temperature gradient from hot to cold across a number of crystals. If the tempco for the crystal is really a parabola, each of the crystals can be a datapoint along the parabola of crystal performance. With a little work you might be able to precisely calculate the maxima of the parabola and precisely set the frequency independent of temp and aging. Ha! jeff _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
