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Frequency-band Transformations 459
1
0.8913
Magnitude Response
1
Phase Response
0.1778
phase in π units
0.5
0
−0.5
decibels
0
0 0.46 0.6 1
Digital frequency in π units
0
1
15
Magnitude in dB
30
0 0.46 0.6 1
frequency in π units
delay in samples
−1
0 0.46 0.6 1
frequency in π units
10
8
6
4
2
Group Delay
0
0 0.46 0.6 1
frequency in π units
FIGURE 8.32 Digital Chebyshev-I highpass filter in Example 8.28
>> % Calculations of Elliptic Filter Parameters:
>> [N,wn] = ellipord(wp/pi,ws/pi,Rp,As);
>> % Digital Elliptic Bandpass Filter Design:
>> [b,a] = ellip(N,Rp,As,wn);
>> % Cascade Form Realization:
>> [b0,B,A] = dir2cas(b,a)
b0 = 0.0197
B = 1.0000 1.5066 1.0000
1.0000 0.9268 1.0000
1.0000 -0.9268 1.0000
1.0000 -1.5066 1.0000
A = 1.0000 0.5963 0.9399
1.0000 0.2774 0.7929
1.0000 -0.2774 0.7929
1.0000 -0.5963 0.9399
Note that the designed filter is a 10th-order filter. The frequency-domain plots
are shown in Figure 8.33.
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