Marechiare wrote:
> Detecting peaks is not a good idea in my opinion. Much better advice
> was:
>
>> 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.

I the simulation I posted here some days ago, I passed the raw samples thru
two poles of low pass filtering, each with a filter fraction of 1/4.  That
means random noise is attenuated by 16.

>> Taking the average of the magnitude and scaling it would probablly
>> be a reasonable option. True RMS is also pretty easy to calculate
>> (square the individual values, average them and take the square root
>> at the end)

True RMS requires much more computation.  It all depends on how much
harmonic content you expect the input to have, and how much you care if it
does.  Since he is measuring the power line, the harmonic content should be
quite low such that little is gained from true RMS.


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