Graphics Programs Reference
In-Depth Information
Completing the integration yields
1
25π
---------
E y
=
[
atanh
2()
–
atanh
()
]
=
0.01799
Joules
Note that an infinite bandwidth would give
E y
=
0.02
, only 11% larger.
The total power associated with a power signal
g ()
is
T
2
1
---
g () 2
P
=
lim
d
(13.50)
T
–
T
2
Define the Power Spectrum Density (PSD) function for the signal
g ()
as
S g ()
, where
T
2
1
---
1
g () 2
------
P
=
lim
d
=
S g () d
(13.51)
T
–
T
2
–
It can be shown that (see Problem 1.13)
G () 2
T
------------------
S g ()
=
lim
(13.52)
T
Let the signals and be two periodic signals with period . The
complex exponential Fourier series expansions for those signals are, respec-
tively, given by
x ()
g ()
T
j nt
T
--------------
x ()
=
X n e
(13.53)
n
=
–
j mt
T
---------------
g ()
=
G m e
(13.54)
m
=
–
The power cross-correlation function
R gx ()
was given in Eq. (13.43), and is
repeated here as Eq. (13.55),
T
2
1
---
g () xt τ
R gx ()
=
(
+
) d
(13.55)
–
T
2
Note that because both signals are periodic the limit is no longer necessary.
Substituting Eqs. (13.53) and (13.54) into Eq. (13.55), collecting terms, and
using the definition of orthogonality, we get
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