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

function wig = WVDist(sig) 
% WVDist -- Wigner-Ville Distribution 
%  Usage 
%    wig = WVDist(sig) 
%  Inputs 
%    sig    1-d signal of dyadic length n=2^J 
%  Outputs 
%   wig     complex-valued matrix representing the Wigner-Ville 
%           distribution of zero-extended signal with rows corresponding 
%           to frequencies and columns corresponding to times. 
% 
%  Side Effects 
%   Image Plot of the Wigner-Ville distribution 
% 
%  See Also 
%   WVDist_AF, TFDist_AF, ImagePhasePlane 
% 
 
sig = sig(:); 
n   = length(sig); 
f   = [zeros(n,1); sig; zeros(n,1)]; 
wig = zeros(n, n); 
ix  = 0:(n/2-1); 
zerosn = zeros(n,1); 
 
for t=1:n, 
        tplus    = n + t + ix; 
    tminus   = n + t - ix; 
    x = zerosn; 
    x(1:(n/2)) = f(tplus) .* f(tminus); 
    wig(:,t) = 2 * fft(x); 
end 
 
abstf = abs(wig); 
tfmax = max(max(abstf)); 
tfmin = min(min(abstf)); 
colormap(1-gray(256)) 
image(linspace(0,1,n),linspace(0,1,n),256*(abstf-tfmin)/(tfmax-tfmin)); 
axis('xy') 
title('Wigner Distribution'); 
xlabel('Time') 
ylabel('Frequency') 
 
% 
% Copyright (c) 1994-5, Shaobing Chen 
% 
     
     
%    
% 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 
%