Hi Artur,
I understand that you want to plot a sine wave and add another sine wave of smaller amplitude to it, so that it looks like noise.
The following code may be helpful:
t = 0:0.01:2;
n_t = length(t);
fs = 1;
signal = sin(2.*pi.*fs.*t);
fn = 10;
noise_Amplitude = 0.1;
sine_noise = noise_Amplitude.*sin(2.*pi.*fn.*t);
plot(t, signal+sine_noise)
If the requirement is to have the original signal and noisy signal in the same plot, the following code may be used:
t = 0:0.01:2;
n_t = length(t);
fs = 1;
signal = sin(2.*pi.*fs.*t);
fn = 10;
noise_Amplitude = 0.1;
sine_noise = noise_Amplitude.*sin(2.*pi.*fn.*t);
plot(t, signal, 'b')
hold on
plot(t, signal+sine_noise, 'r')
hold off
Regards,
Shubhankar.
Best Answer