Subject: Re: [linux-audio-dev] jamin and FFT filtering
From: Alfons Adriaensen (fons.adriaensen_AT_alcatel.be)
Date: Wed Aug 11 2004 - 18:27:28 EEST
On Wed, Aug 11, 2004 at 03:58:40PM +0100, Steve Harris wrote:
> BTW, before you mentioned root raised consine windows before and after, I
> did a bit of googling, and couldn't find much reference to root raised cos
> in windowing (just pentions in-passing), do you have a reference or
> the windowing function/attentuaion factor or anything?
SRRC is used very often in telecomm DSP, but I have not seen it in the
context of analysis or audio. The idea behind my suggestion was just this:
since you do the SRRC twice, the net result after the IFFT is a raised
cosine, and this is perfect to do 2x overlap (or any multiple thereof).
The window function of course is just the square root of a raised cosine.
For an N-point FFT:
W(i) = sqrt (0.5 * (1 - cos (2 * pi * i / N))), i = 0 ... N-1
-- FA
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