[time-nuts] 60hz disciplined watch follow up
Hal Murray
hmurray at megapathdsl.net
Thu Apr 21 19:29:00 UTC 2011
> My estimate of the citizen ecodrives automatic rate adjustment occures at 10 day intervals.
That only works if you can track the signal continuously.
Suppose you lose the signal for a while. How many cycles was that? If it's
only a short while and your clock is stable enough, you can assume you will
come back on the right cycle and only be off a bit on the phase. Your clock
stability determines how long a "short" while is.
Now consider that your watch will be out of contact for 8 hours while you
sleep. If it was accurate to 1 cycle in 8 hours, you wouldn't need to go
through this much effort to calibrate it.
This is similar to the problem of RS-232 clock accuracy. The receiver needs
to be able to determine the difference between N and N+1 identical bits.
--
These are my opinions, not necessarily my employer's. I hate spam.
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