Page 51 - Analog and Digital Filter Design
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48 Analog and Digital Filter Design
natural cutoff Bessel response for comparison. The frequency at which 3dB
attenuation occurs in the natural Bessel response is 2.42 times that of the
modified response, which is designed to give a 3dB cutoff point at 1 rad/s.
90
80
70
60
50
40
30
20
10
0
1 10
F R E Q U E N C Y
Figure 2.4
Bessel ResDonse with Natural and 3dB Cutoff Points
The constant factors for all filter orders up to ten are given in Table 2.1.
The values given were found by practical experiment and are approximately
4(2n -1).ln2, where n is the filter order.
Order, n Normalizing Factor
1 1
2 1.36
3 1.75
4 2.13
5 2.42
6 2.1
7 2.95
8 3.17
Table 2.1 9 3.39
10 3.58
Bessel Normalizing Factors
