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How to add low frequency noise to the signal?

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632541
632541 on 16 Sep 2021
Answered: Mathieu NOE on 16 Sep 2021
How to add low frequency noise (less than 3Hz) to signal in matlab?

Accepted Answer

Mathieu NOE
Mathieu NOE on 16 Sep 2021
hello
this is a simple demo showing a sine signal corrupted by a low frequency noise . You can adjust the parameters to your own needs
Fs = 1000;
samples = 10000;
dt = 1/Fs;
t = (0:samples-1)*dt;
y = 3*sin(2*pi*1*t); % signal - adjust amplitude to your needs
noise = 1.5*randn(size(t)); % noise (before filtering) - adjust amplitude to your needs
% low pass filter : Butterworth filter
NN = 2; % filter order
fc = 3; % cut off frequency (Hz)
Wn = fc/(Fs/2); % normalized cut off frequency
[B,A] = butter(NN,Wn);
noise_filtered = filter(B,A,noise); % noise (after LP filtering)
y_noisy = y+noise_filtered; % signal + noise
figure(1)
plot(t,y,t,y_noisy);legend('signal','signal + noise');

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