File:Signal bruit et fourier.png
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Signal_bruit_et_fourier.png (610 × 461 pixels, file size: 8 KB, MIME type: image/png)
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[edit]Spectre (transformée de Fourier) d'un signal bruité
Spectrum (Fourier transform) of a signal with noise
Auteur/author : Christophe Dang Ngoc Chan (cdang)
Réalisé avec/made with Scilab
clear;clf; // ****************** // variable ajustable p=0.1; // pas // ****************** // variables de base x=[0:p:20*%pi]'; // x du sinus N=size(x); n=N(1,1); // nombre de points s=1/p*(1:n); // fréquences // nombres aleatoires, loi uniforme y2=0.2*(rand(n,1)-0.5); // ****************** // Calcul y1=sin(x); y3=y1+y2; z1=abs(fft(y1))^2; z2=abs(fft(y2))^2; z3=abs(fft(y3))^2; for i=1:n if z1(i)>500 then z1(i)=500; end if z3(i)>500 then z3(i)=500; end end // ****************** // affichage subplot(3,2,1) plot2d(x,y1,style=2,rect=[0,-1.1,60,1.1]) xtitle('signal sinusoïdal','Temps','Intensité') subplot(3,2,2) plot2d(s,z1,style=2,rect=[0,0,0.03,50]) xtitle('TF signal sinusoïdal','Fréq.','Puissance') subplot(3,2,3) plot2d(x,y2,style=2,rect=[0,-1.1,60,1.1]) xtitle('bruit','Temps','Intensité') subplot(3,2,4) plot2d(s,z2,style=2,rect=[0,0,0.03,50]) xtitle('TF bruit','Fréq.','Puissance') subplot(3,2,5) plot2d(x,y3,style=2,rect=[0,-1.1,60,1.1]) xtitle('signal sinusoïdal bruité','Temps','Intensité') subplot(3,2,6) plot2d(s,z3,style=2,rect=[0,0,0.03,50]) xtitle('TF signal sinusoïdal bruité','Fréq.','Puissance')
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[edit]I, the copyright holder of this work, hereby publish it under the following licenses:
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue |
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 16:33, 30 November 2005 | 610 × 461 (8 KB) | Cdang (talk | contribs) | x scale corrected | |
13:49, 30 November 2005 | 620 × 461 (8 KB) | Cdang (talk | contribs) | Spectre (transformée de Fourier) d'un signal bruité ---- Spectrum (Fourier transform) of a signal with noise Auteur/author : Christophe Dang Ngoc Chan (user:cdang) Réalisé avec/made with Scilab |
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