wigner

Arguments

tab

wigner spectrum (lines correspond to the time variable)

x

analyzed signal

h

data window

deltat

analysis time increment (in samples)

zp

length of FFT's. %pi/zp gives the frequency increment.

Description

function which computes the 'time-frequency' wigner spectrum of a signal.

Sample

Examples

a=[488^2 488 1;408^2 408 1;568^2 568 1];
b=[1.28;0;0];
x=a\b;
t=408:568;
p=x'*[t.*t;t;ones(t)];
// unit step function
u=[0*ones(408:487) ones(488:568)];
// finite duration sinusoid
s=p.*sin(2*%pi/16*t+u*%pi);
// signal to be analyzed
s=[0*ones(0:407) s 0*ones(569:951)];
// 64-point rectangular window
h=ones(1,64);
// wigner spectrum
w=wigner(s,h,12,128);
scf();
plot3d(1:69,1:64,abs(w(1:69,1:64)));