> Or have I misunderstood what you were saying? But what happens if, over a day, your DUT 1PPS wanders ahead and/or beyond the REF 1PPS? This is common with GPS 1PPS boards or with too-accurate house 1PPS references or when comparing poor quartz with a GPSDO.
One symptom is that all your TI numbers look positive and right, but the *measurement interval* subtly changes from one clean measurement every 1 second to one clean measurement every 2 seconds. This kind of raw data is hard to process with standard time/frequency stability tools, because they expect tau to be constant. The solution is either a time-stamping counter, or to deliberately offset the DUT or REF by enough microseconds to avoid any sign changes in TIC measurements ever. I'm curious if you've discovered a reliable third alternative. Without reproducing your ARM/START/STOP scenario here myself, it sort of sounds like you're moving the start ahead in time. True, this will give nice valid positive TI measurements but your consistent tau is now silently corrupted. /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.
