
4
4
4
s(t)
=
.5cos2ir
10000
cosß(—
sin2*1000
/
+
sin2*3000/
+
sin2*
5000/)
it
3rc
5*
4
4
4
.5sin2*
10000
sinß(—
sin2*
1000
/
+
sin2*3000/
+
sin2rc5000/)
ir
3*
5*
4
4
4
Sj
=
cos
ß(—
sin2u
1000/
+
sin
2%
3000/
+
sin
2*
5000/)
%
3%
5%
4
4
4
S
0
=
sin
ß(—
sin
2%
1000/
+
sin2*3000/
+
sin2it5000/)
s
(/)
=S
T
+
/
S
n
compemr-
J
I
J
Q
3
b)
Q:
What
are
positive
and
negative
frequency
deviations,
f
and
f".
What
is
the
peak
frequency
deviation?
What
is
the
modualtion
index
(ß)?
Measure
2Af
on
the
spectrum
analyzer
for
this
value
of
ß?
A:
Measured
values
off
1
and
f:
f
=
(1.720
xlO'
3
-
1.58
xlO"
3
)"
1
=
7142
Hz
f
=
(1.250
xlO"
3
-
1.03
xlO"
3
)"
1
=
10.526
«
10
kHz
2Af
=
f
-
f
=
3383
Hz
Af
=
1692
Hz
ß
=
Af/4
=
1692/1000
=1.692
Hz
measured
value
of
2Af
=
10980
-
7568
=
3412
Hz
Q:
Using
Carsons
rule,
what
is
the
bandwidth
for
this
signal?
A:
B
=
2Af+2f
m
=
3
412
+
2(1000)
=
5412
Hz
Lab
3
Solutions
Page
6
76
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