Digital Signal Processing Reference
In-Depth Information
1
0.5
0.4
0
0.2
-0.5
-1
0
0
5
10
15
0
5
10
15
Time index n
Frequency index
1
0.5
0.4
0
0.2
-0.5
-1
0
0
5
10
15
0
5
10
15
Time index n
Frequency index
FIGURE 4.17
Comparison of spectra calculated without using a window function and using a window function to reduce
spectral leakage.
The triangular window:
w
tri
ðnÞ¼
1
j
2
n N þ
1
j
N
1
;
0
n N
1
(4.30)
The Hamming window:
w
hm
ðnÞ¼
0
:
54
0
:
46cos
2
pn
N
1
;
0
n N
1
(4.31)
The Hanning window:
w
hn
ðnÞ¼
0
:
5
0
:
5cos
2
pn
N
1
;
0
n N
1
(4.32)
Plots for each window function for a size of 20 samples are shown in
Figure 4.18
.
The following example details each step for computing the spectral information using the window
functions.
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