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Homework answers / question archive / Malayan Colleges Laguna MITL ECE142 1)determines the number of sideband components in FM
Malayan Colleges Laguna MITL ECE142
1)determines the number of sideband components in FM.
2. One of the following transmits only sideband.
3. What produces the sidebands on FM?
4. Which test instrument displays the carrier and the sidebands amplitude with
frequency to frequency?
5. Mixer is also known as .
6. Which one of the following emission transmit the lower sideband and half of
the upper sideband.
7. An FM receive signal .
8. The process of impressing intelligence on the carrier is called
9. is an electronic instrument used to show both the carrier and the
sidebands of a modulated signal in the frequency domain.
10. What part of the carrier is varied by the intelligence during modulation in an
AM system?
11. The difference between the RF carrier and the modulating signal frequencies is
called the
12. What stage in a radio transmitter isolates the oscillator from the load?
13. The frequency of the unmodulated carrier in FM system is
14. The ratio of maximum deviation to the maximum modulating frequency is called
15. A carrier signal has
16. The modulated peak value of a signal is 125 V and the unmodulated carrier
value is 85 V. What is the modulation index? a. 0.47
b. 0.68
c. 0.32
d. 1.47
17. An 891 kHz carrier having an amplitude of 80 V is modulated by a 4.5 kHz audio
signal having an amplitude of 45 V.. The modulation factor is a. 0.56
b. 0.65
c. 1.78
d. 1.25
18. What is the modulation index of an FM signal having a carrier swing of 75 kHz when the modulating signal has frequency of 3 kHz?
a. 25
b. 12.5
c. 0.04
d. 0.08
19. In a FM system, if modulation index is doubled by halving the modulating
frequency, what will be the effect on the maximum deviation?
20. Which of the following is considered as an indirect method of generating FM?
21. To generate an SSB or DSB signal one must use a circuit known as
22. Which is the first radio receiver?
23. An interfering signal with a frequency equal to the received signal plus twice
the IF is called
24. Double sideband full carrier emission type.
25. Single sideband reduced carrier emission type.
26. A single sideband suppressed carrier emission type.
27. Independent sideband emission type.
28. Vestigial sideband emission type
29. Single sideband full carrier emission type.
30. Phase modulation emission type.
31. Which one is not an advantage of SSB over AM?
32. The advantage of a high level modulated AM transmitter is
33. The advantage of a lowlevel modulated AM transmitter is
34. is the bad effect caused by overmodulation in AM transmission.
35. Which characteristic of a radio receiver refers to its ability to reject an
unwanted signal?
36. What type of emission is frequency modulation?
37. AM transmission power increases with .
38. locks the FM receiver to a stronger signal.
39. What is the highest percentage of modulation for AM? a. 50 %
b. 75 %
c. 100 %
d. 80 %
40. In FM, the Carson's Rule states that the bandwidth is equal to twice the sum
of the modulating frequency and .
41. What is the carrier swing of an FM transmitter when modulated by 75 %?
42. The modulation system inherently more resistant to noise.
43. Subcarriers that are arranged so that the channels occupying adjacent
frequency bands with some frequency space between them is known as
44. Modulation of an RF carrier results in
44. A process which occurs in the transmitter.
45. A process which occurs in the receiver.
46. One part of the transmitter that protects the crystal oscillator from
"pulling".
47. What aspect of the carrier is changed by modulation?
48. The amplitude of a sine wave which is modulated by a musical program will
49. What will be the result of the gain level being too high for signals entering
the modulator?
50. Amplitude modulation causes the amount of transmitter power to
51. When a carrier is modulated 100%, the total power increases by what percentage
over that of the carrier alone? a. 25 %
b. 50 %
c. 75 %
d. 100 %
52. When the amplitude of the modulating voltage is increased for AM, the antenna
current will
53. An increase in transmitter power from 25 W to 30 W will cause the antenna
current to increase from 700 mA to
54. A second modulating tone having the same amplitude but a different frequency
is added to the first at the input to the modulator. The modulation index will be increased by a factor of
55. A 1000 kHz carrier is modulated by a 2500 Hz tone. One frequency component of
the modulated signal is
c. 1002.5 kHz
d. 2500 Hz
56. A 1200 kHz carrier is amplitudemodulated by two tones of 500 Hz and 700 Hz.
Which one is a frequency component of the modulated wave?
a. 1195 kHz
b. 1199.3 kHz
c. 1199.7 kHz
d. 1205 kHz
57. Identify a modulation method, or methods in use for a commonemitter
configuration.
58. The RF signal injected into a balanced modulator is 10 MHz and the modulating
frequency is 1 kHz. Which frequency, or frequencies, will not appear in the output?
c. 10.0001 MHz
d. both A and B
59. Unwanted sidebands in SSB equipment can be suppressed by one or more of the
following methods.
60. Envelope detection is concerned with the process of
61. Diagonal clipping in envelope detection will result in
62. Product detection requires the process of
63. A sine wave which is coherent with carrier has identical
64. Frequency modulation and phase modulation are collectively referred to as
65. In FM the change in carrier frequency is proportional to what attribute of the
modulating signal?
66. A louder sound, when generating the modulating waveform for FM, will cause a
greater
67. If a positive change in modulation signal level of 200 mV will cause a
positive frequency deviation of 10 kHz, what will be the frequency deviation for a negative change of 100 mV in the level of the modulating signals?
c. +5 kHz
d. +0 kHz
68. A particular 15 kHz modulation tone results in a peak frequency deviation of
75 kHz. What is the modulation index?
69. A 15 kHz sine wave frequencymodulates an 88 MHz carrier. A sideband frequency
will be found at a. 87.970 MHz
b. 87.985 MHz
c. 88.015 MHz
d. All of these
70. A device whose capacitance is deliberately made to be a function of the
applied voltage.
71. A reactance modulator is one method of obtaining
72. A device, now available in IC form, is useful for direct FM and as one element
in the phaselocked loop.
73. is a frequency change process, whereby the phase deviation and
frequency deviation are multiplied by some fixed constant.
74. A circuit that has the function of demodulating the frequencymodulated
signal.
75. The ratio detector is superior to the slope detector because
76. One implementation of a pulseaveraging discriminator is
77. A 10% increase in the frequency of a constantwidth pulse train should cause
what change in its average value? a. 10%
b. 1%
c. +1%
d. +10%
78. Two different signals can be coherent if they
79. A quadrature detector requires that
80. In a phaselocked loop, the VCO is the abbreviation for
81. Identify an advantage , or advantages, of a properly designed FM system.
82. The output of a balanced modulator
83. If the modulation index of an AM wave is changed from 0 to 1, the transmitted
power is
84. Which of the following is not a baseband signal of modulation?
