c. amplitude, frequency, and starting point.
d. phase, amplitude, and signal-to-noise ratio.
3. To prevent distortion of the output signal, the operator of an AM radio must
keep modulation from going over 100 percent. At the same time, modulation must be
as near 100 percent as possible to obtain the maximum power output.
Since the
modulating signal may reach a peak amplitude of 30 volts, the carrier must have a
peak amplitude of at least
a. 15 volts.
c.
45 volts.
b. 30 volts.
d.
60 volts.
4. A commercial AM radio station is transmitting a carrier frequency of 1,120
kHz.
The frequency of the modulating signals ranges from 500 Hz to 5 kHz.
The
radio-frequency (RF) stages of the receiver being used to receive these signals
must have a minimum bandwidth of approximately
a. 5 kHz.
c.
560 kHz.
b. 10 kHz.
d.
1,125 kHz.
5. Assume that a phase modulator is producing a 100-kHz carrier.
The phase
deviation limit is 30 when the carrier is modulated by a 1.2-kHz signal.
The
minimum and maximum frequency values of the modulated carrier are approximately
a. zero and 628 Hz.
b. 99,372 Hz and 100,628 Hz.
c. 99,686 Hz and 100,314 Hz.
d. 100,000 Hz and 100,628 Hz.
6. Assume that two identical sine-wave sources are used to modulate two
transmitters--one is FM and the other is phase modulated (PM).
The relationship
between the frequency shifts in the two waves is such that the FM wave is at
a. maximum frequency when the PM wave is at its carrier frequency.
b. minimum frequency when the PM wave is at its maximum frequency.
c. minimum frequency when the PM wave is at its minimum frequency.
d. carrier frequency when the PM wave is at its carrier frequency.
7. Sketch C in figure 17 of TM 11-668 is the block diagram of a PM transmitter.
The section that is relied upon to produce the maximum amount of frequency
deviation is the
a. power amplifier.
b. crystal oscillator.
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