adding 5% white gaussian noise

Hi everyone;
I need to add 5% noise to my signal (amplitude of noise = 0.05* signal amplitude) using "randn" as:
signal_noisy=signal+0.5*randn(signal) % (is it correct?)
is the genereated noise, whight gussion one?!
if I want to use "awgn" is it correct to say in this case SNR=13 ???
I realy appriciate your help here

 采纳的回答

Try this:
% Make sample data.
x = linspace(0, 3*pi, 640);
period = 2*pi;
y = cos(2 * pi * x / period); % Noise-free signal.
% Noise is 5% of the signal value at each location,
% which means sigma is not a constant at each location.
amplitudes = y * 0.05;
noise = amplitudes .* randn(1, length(y));
% Add the noise to the noise-free signal.
yNoisy = y + noise;
% Plot everything.
plot(x, yNoisy, 'r.', 'MarkerSize', 8);
hold on;
plot(x, y, 'b-', 'LineWidth', 2);
grid on;

3 个评论

great thank you; and would this method generate gussion ( flat spactrum ) noise since I am trying to model the measurement noise and it kinda important to be flat spactrum.
Yes, it's flat. The noise depends only on the signal and there is no spatial or time dependency on it, other than the signal itself of course.

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