76 lines
2 KiB
Mathematica
76 lines
2 KiB
Mathematica
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%%% Algorithme de Music pour la d\'etermination des param\`etres Music
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%%%
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%%% entr\'ees :
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%%% - xx : signal
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%%% - pp : ordre du mod\`ele (choisi de mani\`ere ind\'ependante)
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%%% - MM : nombre de coefficients de corr\'elation pris en compte (MM>=pp)
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%%% - fe : fr\'equence d'\'echantillonnage
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%%%
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%%% sorties :
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%%% - ff : fr\'equences auxquelles la dsp a \'et\'e calcul\'ee
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%%% - mydsp : la dsp elle-m\^eme
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%%%
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%%% exemples : clear;rand('seed',100*sum(clock));fe=32000;f0=440;tsig=1280;xx=cos(2*pi*f0/fe*[1:tsig]+2*pi*rand(1,1));mymusic(xx,2,10,fe);
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%%% clear;rand('seed',100*sum(clock));fe=32000;f0=440;tsig=1280;xx=cos(2*pi*f0/fe*[1:tsig]+2*pi*rand(1,1))+cos(2*pi*(f0+26)/fe*[1:tsig]+2*pi*rand(1,1));mymusic(xx,4,300,fe);
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%%%
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%%% S. Rossignol -- 2012
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%%% utilisation en script :
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%clear;rand('seed',100*sum(clock));fe=32000;f0=440;tsig=1280;xx=cos(2*pi*f0/fe*[1:tsig]+2*pi*rand(1,1))+cos(2*pi*(f0+26)/fe*[1:tsig]+2*pi*rand(1,1));pp=4;MM=400;
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%clear;rand('seed',100*sum(clock));fe=32000;f0=440;tsig=1280;xx=cos(2*pi*f0/fe*[1:tsig]+2*pi*rand(1,1))+1e-2*randn(1,tsig);pp=2;MM=10;
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function [ff, mydsp] = mymusic_matlab(xx, pp, MM, fe)
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if (MM<=pp)
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fprintf(1, 'Il faut absolument MM>pp !!!\n');
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return;
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end;
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MM1=MM-1;
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res=xx;
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xx = xx-mean(xx);
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%%% corr\'elations
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acf = xcorr(xx, MM1, 'biased');
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lMM=length(acf);
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rrr1 = acf(MM1+1:lMM)';
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for ii=1:MM1
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rrr1 = [rrr1 acf(MM1+1-ii:lMM-ii)'];
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end;
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rrr1 = rrr1';
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%%% m\'ethode directe pour trouver toutes les valeurs propres
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[v, lambda] = eig(rrr1);
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lamb = diag(lambda);
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[vl,pl] = sort(abs(lamb),'descend');
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%%% densit\'e spectrale de puissance
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df=0.9765625; %%% la dsp est calcul\'ee tous les df Hz
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ff=-fe/2:df:fe/2;
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mydsp=zeros(length(ff),1);
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deni=zeros(MM,MM);
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for ii=pp+1:MM
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deni = deni + v(:,pl(ii))*conj(v(:,pl(ii)))';
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end;
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for ii=1:length(ff)
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ee = cos(2*pi*ff(ii)*[0:MM1]/fe);
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den = conj(ee)*deni*ee';
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mydsp(ii) = abs(1/den);
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end;
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%%% on enl\`eve \'eventuellement une composante non nulle
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mydsp = mydsp-min(mydsp);
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%mydsp = mydsp/max(mydsp); %%% si on fait \c{c}a, c'est norme 1
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end
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