How to add low frequency noise to the signal?

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632541 2021-9-16

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https://ww2.mathworks.cn/matlabcentral/answers/1454334-how-to-add-low-frequency-noise-to-the-signal

回答： Mathieu NOE 2021-9-16

采纳的回答： Mathieu NOE

How to add low frequency noise (less than 3Hz) to signal in matlab?

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Answer 1

Mathieu NOE 2021-9-16

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https://ww2.mathworks.cn/matlabcentral/answers/1454334-how-to-add-low-frequency-noise-to-the-signal#answer_788529

在 MATLAB Online 中打开

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');