On Tue, 20 Dec 2011 13:12:13 +1100 Jim Palfreyman <jim77...@gmail.com> wrote:
> Why don't they build a watch that measures the temperature and every time > you accurately set it, it adds to a small database of time change v > temperature and then adjusts itself internally. > > Over time it would become quite accurate I would think. Because it doesn't work that way. The temperature curve is not linear. So you would need to have a lot of reference points to get an acceptable accuracy. Ie you would need at least a dozen if not more measurements points, then calculate from that the correction factors (which isn't easy if you have no control over the temperature). It's far more economic to put the watch into a climate chamber for half a day and do one or two cycles trough the expected range. This gives you much more accurate data and the watch can then do simple lookup in a table instead of doing complicated calculations. If you do the calibration right, you can quite easily get below 1ppm (not accounting for aging). Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson _______________________________________________ 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.