[time-nuts] Measuring ADEV with a PM6681 or CNT-81
magnus at rubidium.dyndns.org
Sat Oct 25 00:04:36 UTC 2008
Hal Murray wrote:
>> The PM6681 does not appear to have support for measuring time
>> intervals in positive and negative directions at the same time. That
>> would limit the usefulness of this trick, it seems. Or is it just as
>> valid to use the opposite edge of one of the signals?
> Will a long chunk of coax shift one signal far enough so you can be sure of
> the order?
No. Consider a low frequency difference, and you will slowly shift
through all phase relationships. You need to handle them all without
dropping a measurement.
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