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tfrstft

Short time Fourier transform

Calling Sequence

[TFR,T,F] = tfrstft(X)
[TFR,T,F] = tfrstft(X, T)
[TFR,T,F] = tfrstft(X, T, N)
[TFR,T,F] = tfrstft(X, T, N, H
[TFR,T,F] = tfrstft(X, T, N, H, TRACE)
[TFR,T,F] = tfrstft(...,'plot')

Parameters

X :

A Nx elements vector: the signal.

T:

a real Nt vector with elements in [1 Nx] : time instant(s) (default: 1:NX).

N:

a positive integer: the number of frequency bins (default:NX). For faster computation N should be a power of 2.

H:

a real vector with odd length: the analysis window, H being normalized so as to be of unit energy. (default : Hamming(N/4)).

TRACE :

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

'plot':

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

TFR :

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

F :

A N vector of normalized frequencies.

Examples

sig = [fmconst(64,0.2) ; fmconst(64,0.4)]; 
tfr = tfrstft(sig);
clf; gcf().color_map = jetcolormap(128);
subplot(211); grayplot(1:128,1:128,abs(tfr)');
subplot(212); grayplot(1:128,1:128,atan(imag(tfr),real(tfr))');

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