9
Figure 1C.
IN ANSWERING QUESTIONS 1-70 AND
1-71, REFER TO FIGURE 1C.
1-70. What is the phase relationship between
the input signals fed to the diodes?
1. In phase
2. 90 degrees out of phase
3. 180 degrees out of phase
4. 270 degrees out of phase
1-71. A change in oscillator frequency will
change which of the following input
relationships between the sawtooth
reference voltage and the incoming
signal?
1. Phase
2. Voltage
3. Current
4. Amplitude
1-72. How is the long term stability and
accuracy required of modern
communications receivers attained?
1. Through the use of a single, crystal-
controlled oscillator, as the local
oscillator
2. Through the use of an electron-
coupled oscillator, as the local
oscillator
3. Through a process of automatic
frequency control
4. Through a process known as
frequency synthesis
1-73. When using the frequency synthesis
process, a signal of the desired accuracy
and stability is produced by which, if
any, of the following methods?
1. Automatic frequency control, that is,
by sensing the difference between the
oscillator frequency and the desired
frequency and automatically
compensating for this difference
2. Using a crystal-controlled oscillator
to produce a stable high frequency,
and through the process of frequency
division selecting a subharmonic of
this frequency as the desired
frequency
3. The heterodyning and selection of
frequencies which are not
harmonically related to each other
4. None of the above
1-74. Permanent magnet speakers respond
quite well to which of the following
audio frequency ranges?
1. Low
2. High
3. Mid band
4. Each of the above
1-75. For which of the following reasons do
most standard Navy headphones respond
poorly to low frequencies?
1. Small diaphragm size
2. Diaphragm inflexibility
3. Both 1 and 2 above
4. Input signal filtering
