How to Add random noise to a signal
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hello all
please can ou help me out adding a noise signal to my system.
i tried adding a sinus function , but i would like to add a random noise signal rather than the sinus function. I'm running simulation from 1 to 3000
if k>1000 & k<2000
dk(k)=sin(12*k*pi*ts);
x=A*x+B*u(k)+B*dk(k);
else
dk(k)=0;
x=A*x+B*u(k);
end
Thank you so much
Best regards
2 Comments
Image Analyst
on 14 Mar 2020
Moved: DGM
on 4 Mar 2023
What does that mean? Audio IS a signal. You can't add noise to audio without adding it to the signal that defines the audio waveform.
Answers (6)
Thorsten
on 20 May 2015
x = linspace(-2*pi, 2*pi);
plot(sin(x) + 0.5*rand(size(x)))
5 Comments
Image Analyst
on 12 Feb 2020
Tuhin, you can have the amplitude vary with the signal amplitude if you want. For example
% Create noise-only signal.
noisy_signal = rand(size(noise_free_signal));
% Create an amplitude for that noise that is 10% of the noise-free signal at every element.
amplitude = 0.1 * noise_free_signal;
% Now add the noise-only signal to your original noise-free signal to create a noisy signal.
% Be sure to use .*, not *, so that you do element-by-element multiplication.
noisy_signal = noise_free_signal + amplitude .* rand(size(noise_free_signal));
% Adjust amplitude to control the amount of noise.
Now the noise - the max possible noise amplitude - will vary according to the noise-free signal amplitude. Of course since it's noise, the noise won't always be the max possible, it will be less, but it could potentially get that high.
Tuhin Choudhury
on 16 Mar 2020
Edited: Tuhin Choudhury
on 16 Mar 2020
Hi,
Thanks. This would be more of a flexible scaling of the noise w.r.t the input signal.
BR- Tuhin
Image Analyst
on 20 May 2015
So just use rand() instead of sin().
4 Comments
Prajakta Yeola
on 29 Oct 2017
Can we use the same code if audio signal is .wav file? i.e. if x is a .wav file
Image Analyst
on 29 Oct 2017
Sure, just figure out the amplitude and add it
yNoisy = yOriginal + amplitude * rand(1, length(yOriginal));
KL
on 20 May 2015
2 Comments
KL
on 20 May 2015
There's a difference between wgn() and awgn(). With the latter, you add noise throughout the whole range. I understand you want to add noise between certain time intervals. So in this case, I would suggest to use wgn(). At the moment I do not have the toolbox to use this function. Anyhow you shall use this function to calculate the noiseSignal variable according to @Image Analyst's code.
Aparna Gupta
on 21 Jun 2017
Can anyone please help me with the code to add awgn noise to an eeg signal,which i have taken from a database and the file is of .mat type?
1 Comment
Mohammad Sohail Khan
on 3 Nov 2017
Edited: DGM
on 4 Mar 2023
t = 0:pi/100:40;
x = cos(pi/10*t)+0.5*randn(size(t));
plot(t,x)
Then you know where pi/2, 3pi/4 etc are.
0 Comments
Adewale Obaro
on 24 Sep 2018
Edited: DGM
on 4 Mar 2023
N = 1000;
t = 0:1/N:2;
x = sin(2*pi*5*t);
Noise = x + randn(1,N)';
plot(t,Noise);
title('Noise in the Amplitude interval (0,0,1,0)');
ylabel('Amplitude [m]')
xlabel('Time [s]')
0 Comments
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