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| % TRAITEMENT DU SIGNAL
% TD - Applications en vibrations des structures
% Emmanuel FOLTETE
% ACTIVITE 2 - SIGNAUX
% 2.1 Sinus balayé
clear all
close all
% Paramètres d'échantillonnage
SamplingFrequency = 40000 ;
SignalDuration = 1 ;
NbSamples = SignalDuration*SamplingFrequency;
FrequencyResolution = SamplingFrequency/NbSamples,
Time = linspace(0,SignalDuration,NbSamples);
% Sinus balayé
SignalAmplitude = 100 ;
StartFrequency = 100 ;
StopFrequency = 500 ;
L2 = NbSamples * StopFrequency / (StopFrequency - StartFrequency);
w = StopFrequency * pi / (SamplingFrequency * L2);
k = L2-NbSamples:L2-1;
Signal = SignalAmplitude*sin(w * k.^2);
soundsc(Signal,SamplingFrequency);
figure(1);
plot(Time,Signal);
axis([Time(1),Time(end),-SignalAmplitude*1.1,SignalAmplitude*1.1]);
xlabel('Temps (s)');
ylabel('Signal (V)')
title('Sinus balayé','FontWeight','Bold')
% Spectre unilatéral
Spectrum = fft(Signal)/NbSamples;
Spectrum = 2*Spectrum(1:NbSamples/2+1);
Frequency = SamplingFrequency/2*linspace(0,1,NbSamples/2+1);
figure(2)
semilogy(Frequency,abs(Spectrum))
xlabel('Fréquence (Hz)')
ylabel('Amplitude (V)')
title('Sinus balayé','FontWeight','Bold') |
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