Mike Raiford <"m[raiford]!at"@gmail.com> wrote:
> What about using correlation with the desired frequency sine or cosine
> wave? This is essentially what DFT does is correlate input data with a
> series of cosines and sines to get the data into the frequency domain.

Signal -> frequency domain = spectrum
Sine wave -> frequency domain = delta function
Correlation in frequency domain = product.

In other words, this just picks off the nearest frequency (since it probably
won't fit exactly on the scale).  I'm not sure this will improve the precision
quite enough.

>
> Alternatively, you may be able to use a much larger FFT and get a better
> frequency resolution.

You're limited if you want good temporal resolution too.

> I have seen software that can analyze a signal and give its pitch,
> though I'm not sure how it works. I'm sure it's using an FFT, it might
> be using some means of interpolation to estimate where the peak really
> sits.

I would assume those cheap electronic tuners must be using some sort of feedback
loop since they're certainly not FFT'ing it.  So far, the FFT method works
acceptably well, but I'm still curious how it should be done properly.  Thanks
for the advice!

 - Ricky

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