B. P. Lathi, Zhi Ding - Modern Digital and Analog Communication Systems-Oxford University Press (2009)

718 DIGITAL COMMUNICATIONS UNDER LINEARLY DISTORTIVE CHANNELS
Figure 12. 19
Two-ray
multipath
0.6
channel response
for QAM 0.5
transmission.
"'
C:
0.7
0.4
"'
8 0.3
1;l
8
"i:'i
C
C
02
0. 1
0
-0. 1
-0.2
-0.3
0
2 4 6
8 10 12
Time, T,
14 16
18
Figure 12.20 10 °
Power spectral
densities of the
root-raisedcosine
QAM
signal before
and after a
low-pass channel "
"'
of bandwidth ....
0.75/T: (a) input 10- 5
and (b) output of p...
low-pass filter
spectra.
-4
-3 -2
-1
0
Frequency, T,
2
3 4
(a)
, oo
"
10 -5
p...
-4
-3 -2
-1
0
Frequency, T,
2
3 4
(b)