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

Problems 247
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PROBLEMS
Figure P.5. 1 - 1
5.1-1 Sketch 'P FM
(t) and 'P PM
(t) for the modulating signal m(t) shown in Fig. P5.l-1, given W e
10 8 , kf = 10 5 , and kp = 25.
-I
5.1-2 A baseband signal m(t) is the periodic sawtooth signal shown in Fig. P5.l-2.
(a) Sketch 'P PM
(t) and 'Pr M (t) for this signal m(t) if W e = 2rr x 10 6 , kf = 2000n , and kp = rr /2.
(b) Show that the PM signal is equivalent to a PM signal modulated by a rectangular periodic
message. Explain why it is necessary to use kp < rr in this case. [Note that the PM signal
has a constant frequency but has phase discontinuities corresponding to the discontinuities
of m(t).]
Figure P.5. 1 -2
-1
5.1-3 Over an interval ltl I, an angle-modulated signal is given by
'P EM
(t) = IO cos I 3, 0O0rr t
It is known that the carrier frequency W e = 10, 000rr.
(a) If this were a PM signal with kp = 1000, determine m(t) over the interval ltl 1.
(b) If this were an FM signal with kt = 1000, determine m(t) over the interval ltl I.