In this case, the receiver signal acts as a matched filter that is matched to the pulse shaping used in the
transmitter. In fact, it is easy to show that maximum received energy can be extracted when an SRC is
used at the receiver and the transmitter [9].
The impulse response for the SRC filter is given as
(2.5)
IS-95 Pulse-Shaping Filter. In Fig. 2.8, we show the IS-95 pulse-shaping filter and relate it to the
SRC filter used in other standards [10]. (Solid SRC and Dashed IS-95)
h(t)
sin a(1 a)pt
T b
4at
T
# cos a(1 a)pt
T b
pt
T c1 a4at
T b2 d
56 CHAPTER TWO
??“0.4
??“0.2
0
0.2
0.4
0.6
0.8
1
30 40 50 60 70 80 90 100
T/4-Spaced Samples
Amplitude
FIGURE 2.8 Pulse-shaping filter comparison.
2.1.2 Transmit Power Amplifier Discussion
In this section, we will address the issues of the transmit signal (usually in the form of Cartesian coordinates)
by considering the nonlinearity of the transmit PA. Thus far we have discussed the low
pass??“filtering requirements of the modulation schemes as they pertain to the transmit emissions mask
and receiver implications. Another major issue is the susceptibility of the modulation scheme to nonlinearities.
The most significant source of nonlinearity comes from the transmit PA [11].
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