> If you apply the idea of many measurements and averaging you gain accuracy
> by sqrt(Nmeasurements), but is this what you want, or do you want absolute
> instantaneous frequency for logging ?
>
> With a 1/sec readout you should be able to get a 7 times improvement
> (almost 11 times if you measure each half period separately). That would
> put the edge detect/analog part accuracy at 50 usec which is pretty tight
> but can be done imho.

But if you measure 1 second worth (60 cycles) you don't do 60 or 120
independent measurements.  You measure the total time for all 60 cycles,
then divide by 60.  This will reduce any period measurement noise directly
by 60.


********************************************************************
Olin Lathrop, embedded systems consultant in Littleton Massachusetts
(978) 742-9014, olin@embedinc.com, http://www.embedinc.com

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