8. FREQUENCY RESPONSE OF A SYSTEM

FREQUENCY RESPONSE OF A SYSTEM

%to plot the frequency response of a system

b=[1,0,.9];  %numerator coefficients of system1

a=[1,0,.4];  %denominator coefficients of system1

d=[1,-1];   %nulmerator coefficients of system2

f=[1,0.25];  %denominator coefficients of system2

[h,ph]=freqz(b,a);

[h1,ph1]=freqz(d,f);

subplot(2,2,1);

plot(ph/pi,abs(h));

grid;

ylabel('magnitude');

xlabel('normalised frequency');

subplot(2,2,2);

plot(ph1/pi,abs(h1));

grid;

ylabel('magnitude');

xlabel('normalised frequency');

subplot(2,2,3);

plot(ph/pi,angle(h));

grid;

xlabel('normalised frequency');

ylabel('phase in radians');

subplot(2,2,4);

plot(ph1/pi,angle(h1));

grid;

xlabel('normalised frequency');

ylabel('phase in radians');