c.
all of the lower ranges are already full.
d.
FM channels need a broader bandwidth.
13. One of the advantages of FM radio over AM is that FM
a.
is a long-range system.
c.
can be operated as SSB or DSB.
b.
has a narrow bandwidth.
d.
can eliminate amplitude noises.
14. The two methods of modulation most often used in Army FM transmitters are
indirect and direct. In the direct modulation method, the carrier is modulated in
a.
the oscillator.
b.
the final amplifier.
c.
the frequency multiplier.
d.
a stage following the oscillator.
15. The IF signal is produced in the receiver stage known as the
a.
mixer.
c.
b.
detector.
d.
IF amplifier.
16. When the input signal to a receiver is a 1,200-kHz signal and the IF is
455 kHz, the local oscillator must be tuned to a frequency of
a.
1,645 kHz.
c.
745 kHz.
b.
1,200 kHz.
d.
455 kHz.
17. In the AM and FM receivers shown in figure 2-17 there are two circuits in
the FM receiver not found in the AM receiver. What are these two circuits?
a.
IF amplifier and limiter
c.
RF amplifier and detector
b.
Discriminator and limiter
d.
Detector and discriminator
18. The function of the limiter circuit in an FM receiver is to
a.
control the amplitude of the local oscillator output.
b.
limit the frequency variations of the local oscillator.
c.
remove the unwanted amplitude variations from the carrier.
d.
remove the unwanted frequency variations from the carrier.
19. A receiver circuit whose output voltage is proportional to the amount of
frequency deviation that results from modulation is known as a
309 L2
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