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Window Design Techniques 335
Ideal Impulse Response
Hamming Window
1
0.2
0.8
hd(n)
0.1
0
w(n)
0.6
0.4
0.2
−0.1
0 20 40 60
n
Actual Impulse Response
0
0 20 40 60
n
Magnitude Response in dB
0
0.2
h(n)
0.1
Decibels
50
0
−0.1
0 20 40 60
n
0 0.2 0.3 1
frequency in π units
FIGURE 7.16 Lowpass filter plots for Example 7.8
As = 52
% Plots
>> subplot(2,2,1); stem(n,hd); title(’Ideal Impulse Response’)
>> axis([0 M-1 -0.1 0.3]); xlabel(’n’); ylabel(’hd(n)’)
>> subplot(2,2,2); stem(n,w_kai);title(’Kaiser Window’)
>> axis([0 M-1 0 1.1]); xlabel(’n’); ylabel(’w(n)’)
>> subplot(2,2,3); stem(n,h);title(’Actual Impulse Response’)
>> axis([0 M-1 -0.1 0.3]); xlabel(’n’); ylabel(’h(n)’)
>> subplot(2,2,4);plot(w/pi,db);title(’Magnitude Response in dB’);grid
>> axis([0 1 -100 10]); xlabel(’frequency in pi units’); ylabel(’Decibels’)
Note that the Kaiser window parameters are M =61and β =4.5513 and that
the actual stopband attenuation is 52 dB. The time- and the frequency-domain
plots are shown in Figure 7.17.
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