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04116~118
9 18
1
v(x) g(x) δ (x)
v(x) x = 0
∞
∫?∞
v
(
x
)
g
(
x
)dx
=
v
(
0
)
∫ ( )∞ e j2π xydx = δ y ?∞
g ( x)
2 sinc
sinc( x) @sin π x
πx
lim
a→∞
??a
sinc
( ax
)??
=
δ
(
x)
3
g ( x)
g
(
x)
=
?1 ? ?
x
x≤1
? 0 else
s(t)
∑Ps
(
f
)
=
∞ n=?∞
g
(
f? 2n
2n)
s(t)
3dB
90%
4 (1) (2)
z (t ) z (t )
z (t )
Z(f)
Im{z (t)}
t
?f 0, Z ( f ) = 0
0
∫5
g1 ( x) g2 ( x)
∞ ?∞
g1?
(
x
)
g
2
(
x
)
dx
=
0
g1 ( x) g2 ( x)
s1 (t ) s2 (t )
1
v(x) g(x) δ (x)
04116~118
v(x) x = 0
∞
∫?∞
v
(
x
)
g
(
x
)dx
=
v
(
0
)
∫ ( )∞ e j2π xydx = δ y ?∞
g ( x)
∞
∫?∞
v
(
y
)
g
(
y
)dy
=
v
(
0
)
( ) ∫g y = ∞ e j2π xydx ?∞
∫y ≠ 0 g ( y) = ∞ e j2π xydx = 0 ?∞
ε
∫ε
g
(
y
)
dy
=
1
∫∞ g ( y) dy = 1 ?∞
ε
∫?ε
v
(
y
)
g
(
y
)dy
=
v
(
0
)
ε
g(y) 1
∫g ( y) = lim T 2 e j2π xydx = lim T sinc ( yT )
T →∞ ?T 2
T →∞
sinc
sinc( x)
1
2 sinc
sinc
(
x
)
sin π
π x
x
lim
a→∞
??a
sinc
( ax
)??
=
δ
(
x)
3
g ( x)
g
(
x)
=
?1 ? ?
? 0
x
x≤1 else
s(t)
∑Ps
(
f
)
=
∞ n=?∞
g
(
f? 2n
2n)
s(t)
3dB
90%
Ps ( f )
Ps(f)
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
-10
-8
-6
-4
-2
0
2
4
6
8 10
f
g(x) 1
1
3
04116~118
3dB
Ps
(
B3dB
)
=
1 2
Ps
(0)
B3dB = 0.5Hz
B
=1
B90 = 7 ?
10 5
4 z(t) Z ( f )
?f ≤ 0, Z ( f ) = 0
(1) z (t )
Im{z (t)}
0
(2) z (t ) t
(1) z (t )
(2) z (t ) = a (t ) + jb(t ) Z ( f ) = A( f ) + jB ( f ) a (t )
B( f ) b(t)
A( f )
∫5
g1 ( x) g2 ( x)
∞ ?∞
g1?
(
x
)
g2
(
x
)
dx
=
0
g1 ( x) g2 ( x)
s1 (t ) s2 (t )
Parserval
2
04116~118
10 9
1x
p
(
x)
=
1
?x
e2
,
x
≥
0
2
f (x) = e?x
E ?? f ( x)??
20
N0 2
Py
(
f
)
=
?1 ? ?
? 0
f
f ≤1 0
3
Pn
(
f
)
=
?1 ? ? ?
f 0
B
f ? fc ≤ B 0
fc B
n(t) nc (t ) n(t )
(1) nc (t )
Pc ( f )
(2)
no
(t
)
=
dnc (t
dt
)
Po ( f )
4
ai a j
(1) s (t ) (2) s (t ) (3) s (t ) (4) g (t )
∞
s (t ) = ∑ ai g (t ? iT ) i = ?∞
i ≠ j ai
Rs (t,τ ) = E ??s (t ) s (t +τ )?? Rs (τ )
Ps ( f ) δ (t)
{ai } ±1 g (t ) = δ (t )
G( f )
s(t)
5
Pm ( f ) (1) s (t ) (2) s (t )
b (t ) cos (2π fct ) s(t)
b(t)
1x
p
(
x)
=
1
?x
e2
,
x
≥
0
2
f ( x) = e?x
E ?? f ( x)??
∫ ∫E ?? f ( x)?? =
∞
1
?x
e 2 e?xdx
=
1
02 2
∞
?3 x
e2
dx
=
1
03
20
N0 2
Py
(
f
)
=
?1
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