Effect of Noise on Message Signal 2

Matlab program to find effect of Noise on Message Signal when Amplitude and Phase are change at every point, and also find at which point maximum noise is added.

Matlab code

clc;

close all;

clear all;

f=2;% Message Signal frequency.

t=0:.001:1/f;% Define time axis.

A=1+rand(1,length(t));% Message Signal Amplitude

Phase=2*pi*rand(1,length(t));% Message Signal Phase

snr=20; % Assume Signal to noise ratio is 20 db.

for i=1:length(t)

    m=A(i)*sin(2*pi*f*t+Phase(i)); % Message Signal

end;

n=awgn(m,snr); % Adds White Gaussian Noise to signal m.

w=n-m; % Difference b/w Noise Added Signal & Message Signal.

z=abs(w); % Converting -ve value of w in to +ve value.

y=max(z);% Find maximum value of z.

x=find(z==y); % Returns a list of the positions (indices) of z satisfying the given condition.

plot(t,m,'--');

hold on;

plot(t,n,'r');

stem(t(x),n(x),'g','.');

text(t(x)+.005,n(x),'Maximum Noise');

xlabel('Time-->');

ylabel('Amplitude-->');

title('Effect of Noise on Message Signal');

legend('Message Signal without Noise','Message Signal with Noise');

Figure window