Extraction of Periodic signal masked by noise using correlation.
Aim: To extract a periodic signal masked by noise using correlation.
EQUIPMENTS:
PC with windows (95/98/XP/NT/2000).
MATLAB Software.
Program Code:
clear all;
close all;
clc;
n=256;
k1=0:n1;
x=cos(32*pi*k1/n)+sin(48*pi*k1/n);
plot(k1,x)
%Module to find period of input signl
k=2;
xm=zeros(k,1);
ym=zeros(k,1);
hold on
for i=1:k
[xm(i) ym(i)]=ginput(1);
plot(xm(i), ym(i),'r*');
end
period=abs(xm(2)xm(1));
rounded_p=round(period);
m=rounded_p
% Adding noise and plotting noisy signal
y=x+randn(1,n);
figure
plot(k1,y)
% To generate impulse train with the period as that of input signal
d=zeros(1,n);
for i=1:n
if (rem(i1,m)==0)
d(i)=1;
end
end
%Correlating noisy signal and impulse train
cir=cxcorr1(y,d);
%plotting the original and reconstructed signal
m1=0:n/4;
figure
plot(m1,x(m1+1),'r',m1,m*cir(m1+1));
Output:
Result: In this experiment the Extraction of periodic signal masked by noise using correlation have been verified using MATLAB.
Viva Questions:
1. Define the condition for distortion less transmission through the system.
Ans: Transmission is said to be distortion less if the input and output have identical wave shapes within a multiplicative constant.A delayed output that retains the input waveform is also considered distortion less.Thus in distortionless transmission, the input x(t) and output y(t) satisfy the condition:
y(t) = Kx(t  t) where t is the delay time and k is a constant
2. What is filter?
Ans: Electronic filters are electronic circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both.
3. What are lowpass and bandpass filter and what is the difference between these two?
Ans: Lowpass filter allows frequencies below cutoff frequency.
Highpass filter allows frequencies above cutoff frequency
4. Why is the impulse response "finite.
Ans: Impulse response is finite, Because Impulse has only one sample.
5.What is the importance of decimation for a given signal/sequence?
Ans: Decimation for a given signal/sequence will reduce the sampling frequency to required level.

UpdatedFeb 02, 2020

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