Digital Signal Processing Reference
In-Depth Information
Fig. 6.23
(
a
) Original data stream, (
b
) partitioned in-phase data stream, (
c
) partitioned quadrature
phase data stream
mathematical model is as follows:
√
2
d
I
(
t
) cos
ω
c
t
1
ϕ
QPSK
(
t
)
=
ω
c
t
−
d
Q
(
t
)sin
(6.24)
√
2
d
I
(
t
)
ξ
Q
(
t
)
1
=
ξ
I
(
t
)
+
d
Q
(
t
)
Hence, the 4 di-Bit arrangements can be formed taking the help of the Eqs. (
6.24
)
and (
6.19
).
The derived di-bit is indicated into the I-Q diagram of QPSK (Fig.
6.22
b). It's
interesting to note that, one bit (either LSB or MSB) is being changed at a time
when the angle is being increased in steps of
π
4 (Table.
6.6
). This is indeed the
form of Gray code.
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