2.76) [51].
MODULATION THEORY 93
GMSK BT = 0.3 Eye Diagram
??“1.5
??“1
??“0.5
0
0.5
1
1.5
0 4 8 12 16
Normalized Symbol Time (Ts/16)
Eye Value
FIGURE 2.73 GMSK eye diagram with BTb 0.3.
94
Quadrature Phase Baseband Waveform
??“1
??“0.5
0
0.5
1
0 16 32 48 64 80 96 112 128 144 160 176 192
Time
Quadrature Phase Value
FIGURE 2.75 Q-channel waveform.
IJF
+
X
X
cos(wct)
??“sin(wc t)
I(t)
Q(t)
a(t)
Quadrature Modulator
IJF
b(t)
S/P
Tb
b(t ??“ Tb)
m(t)
PA
S(t)
FIGURE 2.76 FQPSK-1 modulation waveform generation block diagram.
FIGURE 2.74 I-channel waveform.
In-phase Channel Baseband Waveform
??“1
??“0.5
0
0.5
1
0 16 32 48 64 80 96 112 128 144 160 176 192
Time
In-phase Channel Value
The IJF pulse-shaping filters had the following responses for the I- and Q-channels:
(2.46)
(2.47)
where the pulse shaping was given as
(2.48)
We can also write the equations at the output of the nonlinear PA as follows:
(2.49)
The IJF-QPSK signal constellation diagram is compared to the IJF-OQPSK constellation (see
Fig. 2.77).
Sout(t)
I(t) # cos (vct) 2I2(t) Q2(t)
Q(t) # sin (vct) 2I2(t) Q2(t)
(Ts t Ts) p(t)
1
2 c1 cos Qpt
Ts Rd
Q(t) b(n)p(t (n 0.5)Ts b(n 1)p(t (n 0.
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