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Time Frequency Toolbox >> Time Frequency Toolbox > Time-Domain Processing > ifestar2

ifestar2

Instantaneous frequency estimation using AR2 modelisation.

Calling Sequence

[FNORM,T2,RATIO]=ifestar2(X,T)
[FNORM,T2,RATIO]=ifestar2(X)

Parameters

X :

real signal to be analyzed.

T :

Time instants (must be greater than 4) (default : 4:length(X)).

FNORM :

Output (normalized) instantaneous frequency.

T2 :

Time instants coresponding to FNORM. Since the algorithm can not always give a value, T2 is different of T.

RATIO :

proportion of instants where the algorithm yields an estimation

Description

ifestar2 computes an estimate of the instantaneous frequency of the real signal X at time instant(s) T. The result FNORM lies between 0.0 and 0.5. This estimate is based only on the 4 last signal points, and has therefore an approximate delay of 2.5 points.

Examples

[x,if]=fmlin(50,0.05,0.3,5); x=real(x); [if2,t]=ifestar2(x);
plot(t,if(t),t,if2);
N=1100; [deter,if]=fmconst(N,0.05); deter=real(deter);
noise=rand(N,1,'normal'); NbSNR=101; SNR=linspace(0,100,NbSNR);
for iSNR=1:NbSNR,
sig=sigmerge(deter,noise,SNR(iSNR));
[if2,t,ratio(iSNR)]=ifestar2(sig);
EQM(iSNR)=norm(if(t)-if2)^2 / length(t) ;
end;
clf(); subplot(211); plot(SNR,-10.0 * log10(EQM)); xgrid;
xlabel('SNR'); ylabel('-10 log10(EQM)');
subplot(212); plot(SNR,ratio); xgrid;
xlabel('SNR'); ylabel('ratio');

See also

Authors

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