MATLAB: Adding noise 15 db

noise

hi everyone.. i want to ask something..

this is my source code..

t=0:0.01:5;

num= [0 0 0.31185 8.28 55.2];

denum=[0.001088 0.044 0.69185 9.28 55.2];

sys=tf(num,denum);

step(sys,t)

grid

title ('Unit-Step Response')

xlabel('t')

ylabel('Amplitudo')

how to adding noise 15 dB to this coding? thanks for your help

Best Answer

I don't know about your coding. However, I add Gaussian noise to a noise free signal, s0, as follows

P0 = mean(s0.^2)

SNR = 10^(SNRdb/10)

s = s0 + sqrt(P0/SNR)*randn(size(s0));

Hope this helps.

Greg

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MATLAB: Adding 5% white gaussian noise

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;

MATLAB: Adding gaussian white noise to data

doc randn

or online

http://www.mathworks.com/help/techdoc/ref/randn.html

Best Answer

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MATLAB: Adding 5% white gaussian noise

MATLAB: Adding gaussian white noise to data

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