Seems to me that 200 ns is 720 degrees of phase error, which is a lot. A person handy with logic circuits could build a simple phase detector with a flip-flop and an RC filter with a tenth second time constant. An analog circuit could detect 360 degree rollover and set off alarm bells. Note that you still have the two-watch problem.
Two equal divider chips ahead of the flip-flop could allow larger errors before rollover. The error may reverse itself and run the phase error down, and then reverse again as the two ovens cycle at different rates. This would be normal behavior, unworthy of an alarm. An additional challenge would be to build logic to select the oscillator output to be distributed, then compare the output to the output of three oscillators in three phase detectors. The device that had phase rollover would put itself in standby, alarm, and leave you with the two watch problem. Perfection demands many oscillators with a voting system. Long winter nights could be spent solving these problems. I'm too old for that stuff. (I also post the most recent ideas first, so as not to reread old ideas.) Bill Hawkins -----Original Message----- From: David VanHorn Sent: Wednesday, October 19, 2011 5:58 PM Magnus said (note the attribution), "Steadily increasing phase error is to let there be a frequency error. Frequency is the derivate of phase, so it comes with the territory. So a 200 ns per second phase drift would provide a frequency error of 2 Hz on your 10 MHz. Can't have one without the other." I understand, I'm just saying that if the absolute phase is wandering a bit over tens of seconds, it's NOT an issue. _______________________________________________ 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.