Digital Signal Processing Reference
In-Depth Information
a (0
a (1
a ()
X (0
X ()
x (0
x (1
N
2 -point
2
X ()
2
a (3
b (0
b (1
b ()
x ()
2
4
X (6
X (1
X (3
X (5
X ()
DFT
x (3
x ()
W N 0
W N 1
W N 2
W N 3
4
x (5
x (6
x ()
1
1
1
1
N
2 -point
2
b (3
DFT
7
7
FIGURE 4.32
The first iteration of the eight-point FFT.
z
y
x
x
x
zwx
x
w
y
y
z
y
1
x
FIGURE 4.33
Definitions of the graphical operations.
N
4
X (0
X ()
x (0
x (1
- point
DFT
4
X ()
W N 0
x ()
2
2
X (6
X (1
X (5
X (3
X ()
N
4
1
1
W N 2
- point
DFT
x (3
x ()
W N 0
W N 1
W N 2
W N 3
4
x (5
x (6
x ()
N
4
1
1
1
1
- point
DFT
W N 0
N
4 - point
DFT
1
1
W N 2
7
7
FIGURE 4.34
The second iteration of the eight-point FFT.
x (0
x (1
X (0
X ()
W N 0
4
X ()
1
W N 0
x ()
2
2
X (6
X (1
X (5
X (3
X
1
1
W N 2
W N 0
x
(3
W N 0
W N 1
W N 2
W N 3
1
x
4
x (5
x (6
x ()
()
1
1
1
1
W N 0
1
W N 0
1
1
W N 2
W N 0
7
()
7
1
FIGURE 4.35
Block diagram for the eight-point FFT (total 12 multiplications).
 
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