If I have a day of good data, then a break, then more good data, how long can the break be so that I can correctly guess the number of cycles that were missed? It depends upon how much the frequency changes. If I extrapolate forward from before the break and back from after, the lines will intersect. If I can estimate the error in the slope of those lines I can see what happens if I use the high/low error cases.
Hal,
Your logic sounds correct. Note the question of how accurately you can predict the future time or frequency of a clock, based on a long record of its past behavior, is exactly what the ADEV family of statistics give you. It's all about how much or little the frequency changes over time. I'll send you mains data from yesterday if you want to play with simulating missing data algorithms. I think in this case TDEV or MTIE is the statistic you want. I had to deal with this issue of data breaks in my relativity clock experiment on Mt Rainier (www.leapsecond.com/great2005, for new people on the list). In this case you have stable clocks and because of time dilation they "slip cycles" so to speak while you are away from home. The question is: how stable a clock do you need to have before you are sure you can see relativistic time dilation and not just nanoseconds of normal clock drift.
One thing that might help get back in cycle sync would be to use a PIC/AVR rather than a 555. The idea is that it can do the first layer of data reduction, say divide by 100. That would roughly multiply the get-back-in-sync time by 100. (assuming not much noise)
Correct. Or divide to get 1 pulse per minute, or hour, etc. You may laugh but even dividing by 5184000 (one pulse per day) would still give you enough points to make a really nice plot of US mains power timekeeping performance over a year. This illustrates the issue that for some cases (such as this one) occasionally recording time error (phase) is often easier and more reliable than making many uninterrupted frequency measurements and integrating them all to estimate net time error. /tvb _______________________________________________ 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.
