In message <005e01c11564$2d6214c0$0556b0c8@brusque>, Edson Brusque
<ebrusque@TERRA.COM.BR> writes
>Hello,
>
>    I'm making an RMS voltage measurement with the PIC at one of my
>circuits.
>
>    Now, how can I get a precise result if I don't know the frequency and
>format of the waveform going to the PIC A/D?
>
>    I mean, if the wave is very clean, like a pure sinusoidal, I could try
>to sample it between two zero-crossings and I will have a very precise
>value. But what about if it does have some loud harmonics? For example, if
>it's a sine with 100Hz plus a sine with 187Hz, both mixed and with the same
>intensity, the zero-crossings will be all over the place so I can't sample
>between two zero-crossing because the values will be meaningless.
>
>    Any ideas?

You can buy chips that do this in hardware, from what I can remember
they are some kind of multiplier?.
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Nigel.

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