To compensate for increases in carrier frequency

27. To compensate for increases in carrier frequency
deviation with an increase in modulating signal
frequency, what circuit is used between the modulating
signal and the phase modulator?
a. Low-pass filter
b. High-pass filter
c. Band-stop filter
d. Band-pass filter
28. The FM produced by PM is called
29. If the amplitude of the modulating signal applied to a
phase modulator is constant, the output signal will be
30. A 100 MHz carrier is deviated 50 kHz by a 4 kHz signal.
The modulation index is
31. The maximum deviation of an FM carrier is 2 kHz by a
maximum modulating signal of 400 Hz. The deviation
ratio is
a. 5
b. 0.2
c. 800
d. none of the above
32. A 70 kHz carrier has a frequency deviation of 4 kHz with
a 1000 Hz signal. How many significant sideband pairs
are produced?
33. What is the bandwidth of the FM signal described in
question 13 above?
34. What is the relative amplitude of the third pair of
sidebands of an FM signal with m = 6
35. A 200 kHz carrier is modulated by a 2.5 kHz signal. The
fourth pair of sidebands are spaced from the carrier by
a. 5 kHz
b. 10 kHz
c. 15 kHz
d. 20 kHz
36. An FM transmitter has a maximum deviation of 12 kHz
and a maximum modulating frequency of 12 kHz. The
bandwidth by Carson’s rule is
37. If the actual deviation of an FM TV sound is 18 kHz, the
percent modulation is

SET B
ECE 121 – Communications 1
Quiz 4 – FM and Multiplexing
4
th
Quarter 2009-10
3
38. Which of the following is not a major benefit of FM over
AM?
39. The primary disadvantage of FM is its
a. noise immunity
b. simple transmitter
c. excessive use of spectrum space
d. none of the above
40. Noise is primarily
41. The receiver circuit that rids FM of noise is the
42. The phenomenon of a strong FM signal dominating a
weaker signal on a common frequency is referred to as
the