It seems to me, that you should run an FFT based sample and determine the
highest output as center frequency.

(Just a thought) Treat the sample as DSP input and process the signal. There
have been many threads on FFT.

Gordon Varney

> Hello,
>
>     I initiated a thread some time ago about how can I make a musical
> instrument tuner (guitar tuner) with a PIC. We have some ideas, but no
> conclusion.
>
>     Sometime before it, Albert Goodwill started a thread called "PIC based
> frequency measurement for musical tunes".
>
>     Well, anyone wants to talk about it again?
>
>     I'm still trying to build it. The biggest problem is that with a
> non-regular wave (lot's of harmonics), it's hard to have a meaningfull
> frequency measurement. My idea is to have a variable PIC-controlled
low-pass
> filter (MAX291/MAX295) to filter the harmonics and have an almost perfect
> sine-wave so I can make the frequency measurement.
>
>     I think it will work, but I can't measure above 2KHz with a MAX291
(max
> PWM output on PIC16F87X at 20MHz is 200KHz) and it will not be automatic.
>
>     Ideas, please?!?!?!
>
>     Best regards,
>
>     Brusque
>
> -----------------------------------
> Edson Brusque
> Research and Development
> C.I.Tronics Lighting Designers Ltda
> (47) 323-2685  /  (47) 9993-6453
> Blumenau  -  SC  -  Brazil
> -----------------------------------
>
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>
>

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