peter green ha scritto:
> A FFT is overkill unless you actually want to measure the harmonics.

indeed, I guess that's true


> 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.

that's true, even if I could perform some averaging here and there.


> 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)

ok


> Ideally for stable values you should detect the zero crossings and do 
> your averaging (whether true RMS or average of the magnitude) over a 
> whole number of half-cycles.

yeah, point taken, will try to use it.


> Also 100Hz is about the worst choice of sampling rate you could pick. 
> Combine that with a 50Hz waveform and you may miss all the peaks! If you 
> want  good results from simple algorithms within a single cycle i'd 
> suggest at least 1KHz. If you are averaging over many cycles and can't 
> afford to sample quickly make sure you select a sample rate that is NOT 
> a multiple or subdivision of the supply frequency!


yeah :) I definitely wrote 100Hz but of course had my mind set elsewhere :)
I agree in that.
The device has actually "plenty of time" to perform even a lot of 
reading, since (as I wrote in my other reply) the response time is in 
the order of seconds.

thank you Peter
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