convolution using Matlab

1. Experiment No: 03
Experiment Name: Write a simple Matlab program to perform Convolution of two signals.
Objectives:
 To learn about Convolution of two signals of a Linear Time Invariant (LTI) System.
 To learn about how to perform Convolution using Matlab code.
Theory:
Convolution:
Convolution is a mathematical operation used to express the relation between input and output of
an LTI system. It relates input, output and impulse response of an LTI system as
y(t)=x(t)∗h(t)
Where
y (t) = output of LTI
x (t) = input of LTI
h (t) = impulse response of LTI
In the below figure we can easily understand the process of Convolution of LTI system,
Figure 01: Process of Convolution in LTI system
Code of Convolution:
clear all;
close all;
m=input('length ');
for i=1:m
x(i)=input('value ');
end
p=input('initial ');
n=input('length ');
for i=1:n
y(i)=input('value ');
end
q=input('initial ');

2. l=m+n-1;
pp=-(p-1);
qq=-(q-1);
lower=pp+qq;
for i=1:1:l
rr(i)=lower;
lower=lower+1;
end
for i=1:1:l
if i<=m
x(i)=x(i);
else
x(i)=0;
end
end
for i=1:1:l
if i<=n
y(i)=y(i);
else
y(i)=0;
end
end
for j=1:1:l
p1=0; q1=j;
for i=1:1:j
p1=p1+x(q1)*y(i);
q1=q1-1;
end
r(i)=p1;
end
stem(rr,r)

3. Input:
length 5
value 1
value 2
value 3
value 4
value 5
initial 1
length 5
value 5
value 4
value 3
value 2
value 1
initial 1
Output:
Comments:
From this lab we know about Convolution and know how to implement Convolution into Matlab
code. This knowledge will help us in further lab work. This lab helps us to clear our idea about
Convolution.
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