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364
AM, FM, and Digital Modulated Systems Chap. 5
0
R
Magnitude spectrum (dB)
10
20
30
h=0.67
0 500 1,000 1,500 2,000 2,500
f 2 f 1
f(Hz)
f c =1170
B T =800
(a) FSK Spectrum with f 2 =1,070 Hz, f 1 =1,270 Hz, and R=300 bits/sec
(Bell 103 Parameters, Originate mode) for h = 0.67
0
R
Magnitude spectrum (dB)
10
20
30
h=1.82
0
500 1,000 1,500 2,000 2,500
f c =1,170
f(Hz)
B T =420
(b) FSK Spectrum with f 2 =1,070 Hz, f 1 =1,270 Hz, and R=110 bits/sec
for h=1.82
0
R
Magnitude spectrum (dB)
10
20
30
h=3.33
0
500 1,000 1,500 2,000 2,500
f 2 f c =1,570 f 1
f(Hz)
B T =1,600
(c) FSK Spectrum with f 2 =1,070 Hz, f 1 =2,070 Hz, and R=300 bits/sec
for h=3.33
Figure 5–26 FSK spectra for alternating data modulation (positive frequencies shown with one-sided
magnitude values). (See Example5_09.m for calculation of this figure.)