PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

Analog and Digital Filters 635

ylabel(‘Input:DC component’);

subplot(3,1,2)

plot(n*T,f1);

ylabel(‘Input:2cos(0.2 t)’);

subplot(3,1,3)

plot(n*T,f2);

ylabel(‘Input:cos(0.5t)’);

xlabel(‘time’)

figure(2)

input = 2.*ones(1,301) + 2*cos(.2*T.*n) + cos(.5*T.*n);

output1 = filter(Pz1,Qz1,input);

output2 = filter(Pz2,Qz2,input);

subplot(3,1,1)

plot(n*T,input), hold on; stem(n*T,input)

ylabel(‘Input sequence’)

subplot(3,1,2);

plot(n*T,output1); hold on; stem(n*T,output1);

ylabel(‘Outputs Chev 1’)

subplot(3,1,3);

plot(n*T,output2);hold on;stem(n*T,output2)

ylabel(‘Outputs Chev 2’)

xlabel(‘nT’);

The script fi le Cheby_1_2 is executed and the results are shown in Figures 6.61

and 6.62.

FIGURE 6.61

Component plots of the input of x(t) of Example 6.11.

2

1

Input: DC component

3

0102030 4050 60 70 80 90

Input: cos (0.5t) 1

01020304050

time

60 70 80 90

0

1

Input: 2cos (0.2t)

2

 2

0102030405060708090

0