CH12.pdf

节选段落一：
4 0100
3 0011 12 1100
4 0100 2 0010
5 0101 10 1010
6 0110 6 0100
7 0111 14 1110
8 1000 1 0001
9 1001 9 1001
10 1010 5 0101
11 1011 13 1101
12 1100 3 0011
13 1101 11 1011
14 1110 7 0111
15 1111 15 1111
FIGURE 12-3
The FFT bit reversal sorting.


节选段落二：
Figure 12-5 shows a flow diagram for combining two 4 point spectra into a
single 8 point spectrum. To reduce the situation even more, notice that Fig. 12-
5 is formed from the basic pattern in Fig 12-6 repeated over and over.


节选段落三：
L
oo
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fo
r
ea
ch
B
ut
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rf
ly
L
oo
p
fo
r
L
ea
ch
s
ub
-D
FT
L
oo
p
fo
r
L
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2N
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This simple flow diagram is called a butterfly due to its winged appearance.
The butterfly is the basic computational element of the FFT, transforming two
complex points into two other complex points.