Marechiare ha scritto:
>>>> Trying to detect the peak value and scale that is IMO a
>>>> bad idea because a single brief spike could throw the
>>>> reading way off.
>> True, but you can filter first and then detect the peaks.
>> Each peak is then the result of a bunch of input samples,
>> and therefore random noise is attenuated.
> 
> Random noise probably would be attenuated indeed, but what if, for
> instance, some power SCR/TRIAC-regulated load were present on the
> line? Tops of the sine would be heavily suppressed, the filter won't
> restore the shape.

I put apart the filtering note, waiting for Olin's reply. (I've actually 
been reading at the PAS code he wrote for me and I can see the IIR 
filter in there - as I suspected he had already shown such a filter... :)

So far, the result is good enough but indeed in real environment there 
might be spikes - though it has to be said that I'll need rather "slow" 
readouts (< 2-3 secs) and I'm already averaging the output, and the 3 peaks.
Since there will be fans and 1CV pump(s), spikes will indeed be there.


>> True RMS requires much more computation.
> 
> Looks like the statement is not true. RMS approach being a "statistic"
> approach does not require that many measurements per sine period as
> the peak-detect polling does to achieve the same precision.

tell me more :)



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Ciao, Dario
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Cyberdyne
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