triple_r wrote:

> 1) Zero-pad the data pre-fft.  (I'm not sure whether this actually improves the
> quality of the information.)
> 
> 2) Use a feedback loop to control the frequency of a test wave.  (I don't know
> what the controller should look like.)
> 
> 3) FFT.  Locate max.  Band-pass.  Inverse-fft.  Count zero-crossings?  (Not
> robust for noisy signals?)

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.

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

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.
-- 
~Mike

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