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Time Frequency Toolbox >> Time Frequency Toolbox > Bilinear Time-Frequency Processing in the Cohen's Class > tfrgrd

tfrgrd

Generalized rectangular time-frequency distribution.

Calling Sequence

[TFR,T,F]=tfrgrd(X)
[TFR,T,F]=tfrgrd(X,T)
[TFR,T,F]=tfrgrd(X,T,N)
[TFR,T,F]=tfrgrd(X,T,N,G)
[TFR,T,F]=tfrgrd(X,T,N,G,H)
[TFR,T,F]=tfrgrd(X,T,N,G,H,RS)
[TFR,T,F]=tfrgrd(X,T,N,G,H,RS,MOVERN)
[TFR,T,F]=tfrgrd(X,T,N,G,H,RS,MOVERN,TRACE)
[TFR,T,F]=tfrgrd(...,'plot')

Parameters

X :

A Nx elements vector (auto-GRD) or a Nx by 2 array signal (cross-GRD).

T:

a real Nt vector : time instant(s) (default: 1:NX).

N:

a positive integer: the number of frequency bins (default:NX).

G:

a real vector with odd length: the time smoothing window, (default :Hamming(N/10)).

It will be normalized such as the middle point equals 1 to preserve signal energy.

H :

real vector with odd length: the frequency smoothing window,(default: Hamming(N/4)).

It will be normalized such as the middle point equals 1 to preserve signal energy.

RS :

a positive scalar: the kernel width (default : 1).

MOVERN :

a positive scalar: the dissymmetry ratio (default : 1).

TRACE :

if nonzero,the progression of the algorithm is shown (default : 0).

'plot':

if one input parameter is 'plot', tfrqview is called and the time-frequency representation will be plotted.

TFR :

A real N by Nt array: the time-frequency representation.

F :

A N vector of normalized frequencies.

Parameters

X :

signal if auto-GRD, or [X1,X2] if cross-GRD.

T :

time instant(s) (default : 1:length(X)).

N :

number of frequency bins (default : length(X)).

G :

time smoothing window, G(0) being forced to 1. (default : Hamming(N/10)).

H :

frequency smoothing window, H(0) being forced to 1. (default : Hamming(N/4)).

RS :

kernel width (default : 1).

MOVERN :

dissymmetry ratio (default : 1).

TRACE :

if nonzero, the progression of the algorithm is shown (default : 0).

'plot':

if one input parameter is 'plot', tfrgrd runs tfrqview. and TFR will be plotted

TFR :

time-frequency representation.

F :

vector of normalized frequencies.

Description

tfrgrd computes the Generalized Rectangular distribution of a discrete-time signal X, or the cross GRD representation between two signals.

Examples

Interactive use

N=128
sig=fmlin(N,0.05,0.3)+fmlin(N,0.15,0.4);
g=window("kr",9,3*%pi); h=window("kr",27,3*%pi);
t=1:N; tfrgrd(sig,t,N,g,h,36,1/5,1,'plot');

Non interactive use

N=128;
sig=fmlin(N,0.05,0.3)+fmlin(N,0.15,0.4);
g=window("kr",9,3*%pi); h=window("kr",27,3*%pi);
t=1:N; 
[TFR,T,F]=tfrgrd(sig,t,N,g,h,36,1/5);
clf;gcf().color_map= jetcolormap(128);
grayplot(T,F,TFR');

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