Aeroflex 2050T SERIES, Руководство по эксплуатации, Страница: 84 / 322

DIGITAL MODULATION MODE
3-35
Differential QPSK
The vector points are the same as for QPSK (Fig. 3-31).
Differential 8PSK
The vector points are the same as for 8PSK (Fig. 3-32).
Phase offset differential PSK
Phase offset differential PSK uses a
π
/2n phase shift between constellation points on the I,Q
diagram where n is the number of bits per symbol. The phase of the previous state is used as the
reference phase for the next state.
Phase offset
π
/2 differential BPSK
The phase offset
π
/2 differential BPSK constellation is defined below and shown in Fig. 3-34.
Data Phase change
00 0°
01
+90°
10 -90°
11 180°
Data Phase change
000 0°
001
+45°
010 +135°
011 +90°
100 -45°
101 -90°
110
180°
111 -135°
Fig. 3-34 Phase offset
π
/2 differential BPSK
constellation
Data Phase change Example
state changes
0 +90° P0
→
P1
1 -90° P0
→
P3