emdc.m

经验模式分解源码 学习希尔波特黄变换的参考程序 源于Internet网络

%EMDC  computes Empirical Mode Decomposition
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%   Syntax
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% [IMF,NB_ITERATIONS]=EMDC(T,X,STOP_PARAMETERS,MAX_IMFS);
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%   Description
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% computes EMD according to [1] with stopping criterion for sifting in [2]:
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%   mean of boolean array {(mean_amplitude)/(envelope_amplitude) > THRESHOLD} < TOLERANCE
%   &
%   |#zeros-#extrema|<=1
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% inputs:	
%       - T: sampling times. If T=[], the signal is assumed uniformly sampled.
%       - X: analyzed signal
%       - STOP_PARAMETERS: parameters for the stopping criterion: 
%         if scalar the value is used to specify THRESHOLD only.
%         otherwise the vector should be: [THRESHOLD,TOLERANCE].
%         if STOP_PARAMETERS is unspecified or empty, default values are used: [0.05,0.05]
%       - MAX_IMFS: maximum number of IMFs to be extracted. If MAX_IMFS is
%         zero, empty or unspecified, the default behavior is to extract as
%         many IMFs as possible.
%         
% outputs: 
%		- IMF: intrinsic mode functions (IMFs) (last line = residual)
%		- NB_ITERATIONS: effective number of sifting iterations for each mode
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%   Examples
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% workspace: 
%  T: 1xN time instants
%  X: 1xN signal data 
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%>>IMF = EMDC(T,X);
%>>[IMF,NB_IT] = EMDC([],X);
%>>IMF = EMDC(T,X,0.1);
%>>IMF = EMDC(T,X,[0.1,0.1]);
%>>[IMF,NB_IT] = EMDC([],X,[],4);
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%   References
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% [1] N. E. Huang et al., "The empirical mode decomposition and the
% Hilbert spectrum for non-linear and non stationary time series analysis",
% Proc. Royal Soc. London A, Vol. 454, pp. 903-995, 1998
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% [2] G. Rilling, P. Flandrin and P. Gon鏰lves
% "On Empirical Mode Decomposition and its algorithms",
% IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing
% NSIP-03, Grado (I), June 2003
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% See also
%  emd_visu (visualization),
%  emd (slow but has many options),
%  emdc_fix (fast implementation of EMD with different stopping criterion)
%  hhspectrum (Hilbert-Huang spectrum)
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% G. Rilling, last modification: 3.2007
% [e-mail]
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% code based on a student project by T. Boustane and G. Quellec, 11.03.2004
% supervised by P. Chainais (ISIMA - LIMOS - Universite Blaise Pascal - Clermont II
% email : [e-mail]).