Digital Signal Processing Reference
In-Depth Information
x
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t
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c
x
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d
y
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y
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j
ω
j
ω
T
P
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C/D
T
P
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C/D
(a)
T
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y
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x
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x
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c
j
ω
j
ω
T
P
(
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P
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D/C
T
D/C
(b)
T
Figure 4.33
. The noble identities, (a) for C/D converters, and (b) for D/C converters.
q
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s
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s
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ω
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e
H
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G
( )
d
e
F
( )
F
(
j
ω
)
+
G
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ω
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D/C
C/D
T
c
c
d
(a)
T
continuous-time
prefilter
continuous-time
postfilter
digital prefilter
digital postfilter
q
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t
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c
s
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n
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s
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n
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j
ω
T
j
ωΤ
F
( )
d
e
F
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j
ω
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H
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j
ω
)
+
G
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j
ω
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e
D/C
G
( )
d
C/D
c
c
T
T
(b)
F
(
j
ω
)
G
(
j
ω
)
combined prefilter
combined postfilter
Figure 4.34
. (a) The digital communication system with a pair of analog pre- and
postfilters, and a pair of digital pre- and postfilters. (b) Equivalent redrawing.
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