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Coherent
Demodulation
Consider
the
signal
y
(
t
) = cos(2
πf
c
t
)
u
(
t
)
where
w
(
t
) = cos(2
πf
c
t
)
is
the
carrier
signal,
and
u
(
t
)
is
the
modulating
signal.
The
modulated
signal,
y
(
t
)
,
has
spectrum
(Fourier
transform)
as
shown
below:
Y(f)
f
f
c
f
c
The
signal
is
to
be
demodulated
by
multiplying
by
cos(2
πf
c
t
)
,
so
that
z
(
t
) = cos(2
πf
c
t
)
y
(
t
)
.
Sketch
the
spectrum
of
z
(
t
)
on
a
3
×
5
card.
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View Full Document Coherent
Demodulation
Consider
the
signal
y
(
t
) = cos(2
πf
c
t
)
u
(
t
)
where
w
(
t
) = cos(2
πf
c
t
)
is
the
carrier
signal,
and
u
(
t
)
is
the
modulating
signal.
The
signal
is
to
be
demodulated
by
multiplying
by
cos(2
πf
c
t
)
,
so
that
z
(
t
) = cos(2
πf
c
t
)
y
(
t
)
.
Sketch
the
spectrum
of
z
(
t
)
on
a
3
×
5
card.
My
conﬁdence
that
I
have
the
correct
answer
is:
1.
100%
2.
80%
3.
60%
4.
40%
5.
20%
6.
0%
Coherent
Demodulation
The
transform
of
z
(
t
)
is
given
by:
Y(f)
f
2f
c
2f
c
My
answer
1.
Was
completely
correct
2.
Was
mostly
correct,
with
one
or
two
minor
errors
3.
Had
many
errors
4.
Was
completely
incorrect
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View Full Document Coherent
Demodulation
with
Phase
Error
Consider
the
signal
y
(
t
) = cos(2
πf
c
t
)
u
(
t
)
where
w
(
t
) = cos(2
πf
c
t
)
is
the
carrier
signal,
and
u
(
t
)
is
the
modulating
signal.
The
modulated
signal,
y
(
t
)
,
has
spectrum
(Fourier
transform)
as
shown
below:
Y(f)
f
f
c
f
c
The
signal
is
to
be
demodulated
by
multiplying
by
sin(2
πf
c
t
)
,
so
that
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This note was uploaded on 01/28/2012 for the course AERO 16.01 taught by Professor Markdrela during the Fall '05 term at MIT.
 Fall '05
 MarkDrela

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