15
Figure 2E.—Phase relationships.
IN ANSWERING QUESTION 2-34, REFER TO
FIGURE 2E.
2-34. In the figure, (a) waveform X has what
phase relationship to waveform Y, and
(b) waveform Y has what relationship to
waveform Z?
1. (a) Lags (b) leads
2. (a) Lags (b) lags
3. (a) Leads (b) lags
4. (a) Leads (b) leads
2-35. A 10 kilohertz, 10-volt square wave is
applied as the phase-modulating signal to
a transmitter with a carrier frequency of 60
megahertz. What is the output frequency
during the constant-amplitude portions of
the modulating signal?
1. 10 kilohertz
2. 59,990 kilohertz
3. 60,000 kilohertz
4. 60,010 kilohertz
2-36. In a phase modulator, the frequency
during the constant-amplitude portion of
the modulating wave is the
1. peak frequency
2. rest frequency
3. deviation frequency
4. modulating frequency
2-37. In phase modulation, (a) the
AMPLITUDE of the modulating signal
determines what characteristic of the
phase shift, and (b) the FREQUENCY of
the modulating signal determines what
characteristic of the phase shift?
1. (a) Rate (b) rate
2. (a) Rate (b) amount
3. (a) Amount (b) amount
4. (a) Amount (b) rate
2-38. The frequency spectrums of a phase-
modulated signal resemble the spectrum of
which, if any, of the following types of
modulation?
1. Amplitude modulated
2. Frequency modulated
3. Continuous-wave modulated
4. None of the above
2-39. Compared to fm, increasing the
modulating frequency in phase modulation
has what effect, if any, on the bandwidth
of the phase-modulated signal?
1. It increases
2. It decreases
3. None
2-40. A simple phase modulator consists of a
capacitor in series with a variable
resistance. What total amount of carrier
shift will occur when X
C
is 10 times the
resistance?
1. 0 degrees
2. 45 degrees
3. 60 degrees
4. 90 degrees
2-41. The primary advantage of phase
modulation over frequency modulation is
that phase modulation has better carrier
1. power stability
2. amplitude stability
3. frequency stability
4. directional stability
