Page 214 - Fundamentals of Communications Systems

6.36 Chapter Six

= 50 Watt transmitter output
(c) Give the value of A c that will produce a P x z
power in a 1 system.
(d) Sketch the demodulation process for a received signal y c (t).

Problem 6.17. Repeat Problem 6.16 with the bandlimited message signal of
Problem 5.2.
Problem 6.18. Repeat Problem 6.16 with the message signal of Problem 5.5.

Problem 6.19. This problem is concerned with large carrier amplitude modula-
tion (LC-AM) by the message signal given in Problem 5.1. Assume a carrier
frequency of f c = 200 Hz, a carrier amplitude of A c , and a modulation coeffi-
cient of a.

(a) Give the baseband, x z (t), and bandpass, x c (t), time waveforms for LC-AM
for this message signal as a function of m(t).
(b) Give the Fourier series representation of the bandpass modulated signal as
a function of A c and a.
(c) Give the value of a such that the MCPR is maximized and distortion-free
envelope detection is still possible.
(d) What is the MCPR with the value of a computed in (c)?
(e) With the value of a computed in (c) give the value of A c that will produce a
= 50 W transmitter output power in a 1- system.
P x z
(f) Sketch the demodulation block diagram for a received signal y c (t).

Problem 6.20. Repeat Problem 6.19 with the message signal of Problem 5.2.

Problem 6.21. Repeat Problem 6.19 with the message signal of Problem 5.5.
Problem 6.22. This problem is concerned with single sideband amplitude modu-
lation (SSB-AM) by the message signal given in Problem 5.1. Assume a carrier
frequency of f c = 200 Hz, and a carrier amplitude of A c .

(a) Give the baseband, x z (t), and bandpass, x c (t), time waveforms for an upper
sideband SSB-AM for this message signal.
(b) Give the Fourier series representation of the bandpass modulated signal as
a function of A c .
(c) Give the value of A c that will produce a 50 W output power in a 1- system.
(d) Sketch the demodulation block diagram for a received signal, y c (t), assum-
ing that you know φ p .

Problem 6.23. Repeat Problem 6.22 with the message signal of Problem 5.2.

Problem 6.24. Repeat Problem 6.22 with the message signal of Problem 5.5.