Find frequency response of a given system given in (Transfer Function/ Differential equation form
Aim: To write a MATLAB program to evaluate the Frequency response of the system .
Objective: To write a MATLAB program to evaluate the Frequency response of the system .
EQUIPMENTS:
Operating System  Windows XP
Constructor  Simulator
Software  CCStudio 3 & MATLAB 7.5
MATLAB PROGRAM:
clc;
clear all;
close all;
% Difference equation of a second order system
% y[n]0.25y[n1]+0.45y[n2]=1.55x[n]+1.95x[n1]+ 2.15x[n2]
b=input('enter the coefficients of x(n),x(n1)');
a=input('enter the coefficients of y(n),y(n1)');
N=input('enter the number of samples of frequency response ');
[h,t]=freqz(b,a,N);
subplot(2,1,1);
% figure(1);
plot(t,h);
subplot(2,1,2);
% figure(2);
stem(t,h);
title('plot of frequency response');
ylabel('amplitude');
xlabel('time index>N');
disp(h);
grid on;
OUTPUT:
enter the coefficients of x(n),x(n1)[1.55 1.95 2.15]
enter the coefficients of y(n),y(n1)[1 .25 .45]
enter the number of samples of frequency response 1500
RESULT: The frequency response of given Differential equation is obtained. Hence the theory and practical value are proved.
Objective: After finishing this experiment the students are able to
calculate and plot a frequency response of given Differential equation is obtained. Hence the theory and practical value are proved.
Viva QUESTIONS:
? Which built in function is used to solve a given difference equation?
? What is frequency response? Give equation for first order system and second order system?
? What is an LTI system?
? What is steady state response?
? Suppose we have a system with transfer function H(z) = 1 / ((z – 1.1)*(z – 0.9)). Is the system stable or unstable?
? What is Auto Regressive Model? How is the order of auto regressive model is decided?

UpdatedFeb 03, 2020

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