
241Advanced Modulation Format Optical Transmitters
An MSK signal consists of both I and Q components, which can be written as
s t
E
T
t f t
E
T
t f t
b
b
c
b
b
c
( )
=
( )
−
( )
2
2
2
2cos cos sin sinθ π θ π
(6.12)
The in-phase component consists of half-cycle cosine pulse dened by
s t
E
T
t
T
T t T
I
b
b b
b b
( )
= ±
− ≤ ≤
2
2
cos ,
π
(6.13)
while the quadrature component would take the form
s t
E
T
t
T
t T
Q
b
b b
b
( )
= ±
≤ ≤
2
2
0 2sin , .
π
(6.14)
Between even-bit intervals, the I component consists of the positive cosine waveform
for phase of 0, and the negative cosine waveform for phase of π; between odd-bit inter-
vals, the Q component consists of positiv ...