Orchid XP v8 wrote:

> Recall that the convolution of a signal by some kernel is *longer* than 
> the original signal. This is the effect you have to repeat when doing 
> FFT convolution. (The details escape me at this exact moment... Suffice 
> it to say that your inverse-FFT results have to be overlapped to get a 
> smooth result.)
> 

Looking at dspguide.com (The first site that actually got me to make a 
bit of sense out of FFT in the first place) it seems the overlap is 
quite simple. What to overlap seems to be the length of the filter 
kernel... But, how do you determine that if, say ... you present the 
user with an interface that allows them to create a graph of which 
frequencies to pass...?

I suppose this is where you'd want to use a Blackmann window to clean up 
the edges of the kernel before applying it to the input data.


-- 
~Mike

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