www.pudn.com > TimeFrequency.rar > IWindowFT.m

function sig = IWindowFT(specgm,w,Name) 
% IWindowFT -- Inverse Window Fourier Transform 
%  Usage 
%    sig = IWindowFT(specgm,w,Name) 
%  Inputs 
%    specgm    Window Fourier Transform of sig, complex matrix 
%    w        window half-length used to construct specgm 
%    Name     string: 'Rectangle', 'Hanning', 'Hamming', 
%             'Gaussian', 'Blackman'  
%              name of window used to construct specgm 
%  Outputs 
%    sig      1-d signal 
%  Side Effects 
%    none 
%  Description 
%     supposes signal is non-periodic, i.e. zero-padded 
%     reconstruction is not exact in the border region, but it is 
%     exact in the center 
%  See Also 
%    WindowFT 
%  References 
%    Mallat, "A Wavelet Tour in Signal Processing";  
%            4.2.3 Discrete Windowed Fourier Transform. 
% 
 
[n,nw] = size(specgm); 
f = zeros(3*n,1); 
totseg = zeros(3*n,1); 
win    = MakeWindow(Name,w); 
win    = win(:); 
window = zeros(3*n,1); 
window(n+1-w:n+1+w,1) = win; 
 
for i = 1:nw, 
	totseg(n+1:2*n) = ifft(specgm(:,i)'); 
	f = f + window.*totseg; 
	window = rshift(window')'; 
end; 
f = f(n+1:2*n); 
sig = f/norm(window)^2.; 
% 
% Copyright (c) 1997. Maureen Clerc and Jerome Kalifa 
% clerc@cmapx.polytechnique.fr, kalifa@cmapx.polytechnique.fr 
     
     
%    
% Part of WaveLab Version 802 
% Built Sunday, October 3, 1999 8:52:27 AM 
% This is Copyrighted Material 
% For Copying permissions see COPYING.m 
% Comments? e-mail wavelab@stat.stanford.edu 
%