UploadFile_6417

220 Chapter 6 IMPLEMENTATION OF DISCRETE-TIME FILTERS
Solution
MATLAB script:
>> b=[1 -3 11 -27 18]; a=[16 12 2 -4 -1];
>> [b0,B,A]=dir2cas(b,a)
b0 = 0.0625
B =
1.0000 -0.0000 9.0000
1.0000 -3.0000 2.0000
A =
1.0000 1.0000 0.5000
1.0000 -0.2500 -0.1250
The resulting structure is shown in Figure 6.6. To check that our cascade structure
is correct, let us compute the first 8 samples of the impulse response using
both forms.
>> delta = impseq(0,0,7)
delta =
1 0 0 0 0 0 0 0
>> format long
>> hcas=casfiltr(b0,B,A,delta)
hcas =
Columns 1 through 4
0.06250000000000 -0.23437500000000 0.85546875000000 -2.28417968750000
Columns 5 through 8
2.67651367187500 -1.52264404296875 0.28984069824219 0.49931716918945
>> hdir=filter(b,a,delta)
hdir =
Columns 1 through 4
0.06250000000000 -0.23437500000000 0.85546875000000 -2.28417968750000
Columns 5 through 8
2.67651367187500 -1.52264404296875 0.28984069824219 0.49931716918945
□
FIGURE 6.6 Cascade structure in Example 6.1
Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it.