Calculate Wigner distribution

Calculates the 2D Wigner distribution of a complex function.

Description

W = mywigner(Ex)

W = output Wigner distribution
Ex = Input electric field (MUST be a column vector

Notes:
W = Int(-inf..inf){E(x+y)E(x-y)exp[2ixy]}
E(x+y) & E(x-y) are calculated via a FFT (fast Fourier transform) using the
shift theorem. The integration is performed via a FFT. Thus it is important for the data to satisfy the sampling theorem:
dy = 2*pi/X X = span of all x-values dy = y resolution
dx = 2*pi/Y Y = span of all y-values dx = x resolution
The data must be completely contained within the range x(0)..x(N-1) & y(0)..y(N-1) (i.e. the function must fall to zero within this range).

• MATLAB release: MATLAB 7.4 (R2007a)

[ashutosh singh]

 

[kim ngan tran]

 

[Herliyani Hasanah]

Very good

[VictorF Dios]

The user has to add a multiplication for incr_x in order to preserve the energy of the signal.

[RIPUL Ghosh]

i am working on seismic data that has a total length of almost 100000 data point.When i am running wigner distribution it is showing 'out of memory'.

[Adam Wyatt]

You have to think what you are doing - given data of length N, the Wigner distribution is N^2, so clearly with N=10^5, N^2 = 10^10 - you're not going to ever be able to make such a Wigner distribution.

However, it is possible that you do not need the Wigner distribution over the whole temporal and spectral domains. Unfortunately I have not implemented this yet.

[michael scheinfeild]

 

[michael scheinfeild]

your delay is always half of the signal
the matrix can be too large
for chirp test the max locations should be at phase 2*f*b*t but the max is alwayes at the center