Well, I suppose he is looking for frequencies (plural) and
wants to reject noise that is other frequency mostly, then FFT
methods will sift those several frequencies out.

IF there is only a sorta clean
sorta sine wave on the line, then zero crossing will do.

Maybe there is stuff from other active sensors rolling around nearby
coming in on his line that he wants to reject....

John G.
Austex

> -----Original Message-----
> If you're just getting frequency, why not just look for a
> zero crossing and not much about with the ADC.
>
> Hardware becomes a 1 bit comparator. Time positive transition
> to positive transition. 'Blank' after negative transitions for
> a short (compared to expected frequency) to prevent noise from
> making false counts.
>
>
>
> --
> Anniepoo
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