Adding Noise to Signal through Rand function?

Hello everyone, I just want a simple help as I am new to matlab.

I want to add Noise to my Signal through rand function but its giving error. Kindly if anyone can see how am i doing it wrong. Thoguh its just few lines from a long code which works perfectly without this noise addition.

noise = 2*rand (size(time));

y2t=noise+y22t; // y22t is the signal

plot(time*1e9,y2t,'-k','LineWidth',2);

xlabel('Time - [ns]');ylabel('Amplitude - [V]');

hold on;

grid on;

Answer 1

[Image Analyst]

Try this:

t = 1 : 50; % Whatever.
y22t = 2 * sin(2 * pi * t / 15);
subplot(2, 1, 1);
plot(t, y22t, 'b-', 'LineWidth', 2);
grid on;
xlabel('Time - [ns]', 'FontSize', 15);
ylabel('ytt', 'FontSize', 15);
title('Noise-free y22t', 'FontSize', 15);

noise = 2*rand (size(t)); % To go on both sides of the signal, use 2*rand (size(t)) - 1
y2t=noise+y22t;   % y22t is the signal
subplot(2, 1, 2);
plot(t,y2t,'-k', 'LineWidth',2);
xlabel('Time - [ns]', 'FontSize', 15);
ylabel('Amplitude - [V]', 'FontSize', 15);
title('Noisy y22t', 'FontSize', 15);
hold on;
grid on;

Don't use time as the name of your variable since it's the name of a built-in function.

[Syed Adeel]

@image Analyst Thankyou so much for your to the point reply.

I got your point and tried it in code. Just a bit more of querry

% To go on both sides of the signal, use 2*rand (size(t)) - 1

First, Is that 2 the amplitude or something else?

Secondly, y2t was my output of the code but in actual i need to add the bandwidth liimited with mean value 0 noise at the input stage which is "x1s":

%%% Plot in Time-Domain %%% %%% %%% %%% %%% %%% %%% %%% %%% %%% %%% %%% %%%

syms t;

to1=1e-9;

to2=to1+QTIME;

%%% Input Signal Laplace Transform

x1s=(exp(-s*to1))*1/s-(exp(-s*to2))*(1/s); % This is the input

I=Q/QTIME;

x1s=I*x1s;

x1t=ilaplace(x1s);

ys1=x1s*tfvout1; % tfvout1 is the trasfer function of system from which i calculate the output

Can you help with it?

[Image Analyst]

Yes, 2 is the amplitude of the noise. It can be whatever you want.

Sorry I can't help with the second part. I don't have the Symbolic Toolbox and haven't dealt with Lalace Transforms since I was an undergraduate many decades ago.