diff dsp/wigner.m @ 32:c3b0cd708782

Imported core dsp tools.

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dsp/wigner.m	Sun Jan 20 13:48:47 2013 +0000
@@ -0,0 +1,42 @@
+function wig = wigner(sig,m,l,k,win)
+% Wigner -- Wigner-Ville Distribution. This version
+%           operates on an entire signal in a vector. 
+%  Usage
+%    wig = wigner(sig,m,l,k,win)
+%  Inputs
+%    sig    1-d signal
+%    m      half window length (must be power of 2)
+%    l      number of frequencies (ie rows in output)
+%    k      window step (defaults to 1)
+%    win    half window of size m+1
+%  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
+%
+
+sig = sig(:);
+n   = length(sig);
+
+if nargin<4 k   = 1; end
+if nargin<3 l   = m+1; end
+if nargin<5 win = ones(m+1,1); end
+   
+f   = [zeros(m,1); sig; zeros(m,1)];
+wig = zeros(l,floor(n/k));
+ix  = 0:m;
+
+col=1;
+for t=1:k:n,
+    tplus    = m + t + ix;
+    tminus   = m + t - ix;
+    R = win .* ( f(tplus) .* f(tminus) );
+    x = [ R(1:m); R(m+1:-1:2) ];
+    y = fft(x);
+    wig(:,col) = real(y(1:l));
+    col = col+1;
+end
+