
467Digital Optical Modulation Transmission Systems
1.5
1
0.5
0
–0.5
Quadrature amplitude
–1
–1.5
–1.5 –1 –0.5 0
In-phase amplitude
0.5 1 1.5
Scatter plot
Quadrature amplitude
–1.5 –1 –0.5 0
In-phase amplitude
0.5 1 1.5
1.5
1
0.5
0
–0.5
–1
–1.5
Scatter plot
Quadrature amplitude
–1.5 –1 –0.5 0
In-phase amplitude
0.5 1 1.5
1.5
1
0.5
0
–0.5
–1
–1.5
(c)
2.5
2
1.5
1
0.5
0
–0.5
–1
–1.5
–2
–2.5
0 10 20 30
Time (ps)
Amplitude
Frame: 448
5040 60 70
(b)
1.5
1
0.5
0
–0.5
–1
– 1.5
Amplitude
0 10 20 30
Time (ps)Frame: 468
5040 60 70
(a)
1.5
×10
–3
×10
–3
×10
–3
1
0.5
0
–0.5
–1
– 1.5
Amplitude
0 10 20 30
Time (ps)
5040 60 70
FIGURE 11.17
Signal
constellation and eye diagrams of MSK optical signals: (a) linear, (b) weakly non