The implementation and theory of correlator-type receivers can
be found in Detection.
m
^
=2
m
^
2
since
Dr
s
1
>Dr
s
2
D
r
s
1
D
r
s
2
or
∥
s
1
∥2=∥
s
2
∥2
s
1
2
s
2
2
and
〈r,
s
2
〉>〈r,
s
1
〉
r
s
2
r
s
1
.
Data symbols "0" or "1" with equal probability. Modulator
s
1
t=st
s
1
t
s
t
for
0≤t≤T
0
t
T
and
s
2
t=−st
s
2
t
s
t
for
0≤t≤T
0
t
T
.
ψ
1
t=stA2T
ψ
1
t
s
t
A
2
T
,
s
11
=AT
s
11
A
T
, and
s
21
=−(AT)
s
21
A
T
∀
m
,m=12:
r
t
=
s
m
t+
N
t
m
m
1
2
r
t
s
m
t
N
t
(1)
r
1
=AT+
η
1
r
1
A
T
η
1
(2)
or
r
1
=−(AT)+
η
1
r
1
A
T
η
1
(3)
η
1
η
1
is Gaussian with zero mean and variance
N
0
2
N
0
2
.
m
^
=argmaxAT
r
1
−(AT
r
1
)
m
^
A
T
r
1
A
T
r
1
, since
AT>0
A
T
0
and
Pr
s
1
=Pr
s
1
s
1
s
1
then the MAP decision rule decides.
s
1
t
s
1
t
was transmitted if
r
1
≥0
r
1
0
s
2
t
s
2
t
was transmitted if
r
1
<0
r
1
0
An alternate demodulator:
(
r
t
=
s
m
t+
N
t
)⇒(r=
s
m
+η)
r
t
s
m
t
N
t
r
s
m
η
(4)