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 4thQuarter 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
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