Online Questions and Answers Topic Outline
- MCQs in Amplitude Modulation
- MCQs in Phase Modulation
- MCQs in Sound Pressure Level
- MCQs in Frequency Modulation
- MCQs in Pulse Modulation
MCQs in Modulation Series
Following is the list of multiple choice questions in this brand new series:
Start Practice Exam Test Questions Part I of the Series
1. ______ is the maximum sideband suppression value using filter system.
- A. 50 dB
- B. 60 dB
- C. 40 dB
- D. 30 dB
2. _______ determines the number of sideband components in FM.
- A. carrier frequency
- B. modulation frequency
- C. modulation index
- D. deviation ratio
3. One of the following transmits only one sideband.
- A. H3E
- B. R3E
- C. A3E
- D. B8E
4. What produces the sidebands on FM?
- A. signal amplitude
- B. carrier harmonics
- C. baseband frequency
- D. broadband frequency
5. Which test instrument displays the carrier and the sidebands amplitude with frequency to frequency?
- A. oscilloscope
- B. spectrum analyzer
- C. frequency analyzer
- D. amplitude analyzer
6. Mixer is also known as a ________.
- A. modulator
- B. suppressor
- C. converter
- D. beater
7. Which one of the following emission transmits the lower sideband and half of the upper sideband?
- A. A5C
- B. J3E
- C. A3J
- D. A3H
8. An FM receives signal ______.
- A. vary in amplitude with modulation
- B. vary in frequency with modulation
- C. vary in frequency and amplitude with wideband modulation
- D. is not immune to noise
9. The process of impressing intelligence on the carrier is called
- A. modulation
- B. detection
- C. mixing
- D. impression
10. ______ is an electronic instrument used to show both the carrier and the sidebands of a modulated signal in the frequency domain.
- A. spectrum analyzer
- B. oscilloscope
- C. digital counter
- D. frequency counter
11. What part of the carrier is varied by the intelligence during modulation in an AM system?
- A. phase
- B. frequency
- C. amplitude
- D. both a and c
12. The difference between the RF carrier and the modulating signal frequencies is called the
- A. USB
- B. LSB
- C. Sideband
- D. Carrier frequency
13. What stage in a radio transmitter isolates the oscillator from the load?
- A. Oscillator
- B. Buffer
- C. Separator
- D. Mixer
14. The frequency of the unmodulated carrier in FM system is
- A. modulating frequency
- B. center frequency
- C. carrier frequency
- D. deviation frequency
15. The ratio of maximum deviation to the maximum modulating frequency is called
- A. carrier swing
- B. deviation ratio
- C. modulation factor
- D. modulation index
16. A carrier signal has
- A. constant amplitude
- B. a frequency of 20 kHz and above
- C. a varying amplitude
- D. the information content
17. 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
18. 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
19. 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
20. In a FM system, if modulation index is doubled by having the modulating frequency, what will be the effect on the maximum deviation?
- A. No effect
- B. Maximum deviation doubles
- C. Decreases by ½
- D. Increases by ¼
21. Which of the following is considered as an indirect method of generating FM?
- A. Reactance modulator
- B. Balanced modulator
- C. Varactor diode modulator
- D. Armstrong system
22. To generate an SSB or DSB signal one must use a circuit known as
- A. filter modulator
- B. ring modulator
- C. balanced modulator
- D. reactance modulator
23. Which is the first radio receiver?
- A. TRF receiver
- B. Superheterodyne receiver
- C. Crystal radio receiver
- D. Heterodyne receiver
24. An interfering signal with a frequency equal to the received signal plus twice the IF is called
- A. image frequency
- B. center frequency
- C. rest frequency
- D. interference frequency
25. Double sideband full carrier emission type
- A. A3J
- B. H3E
- C. R3A
- D. A3E
26. Single sideband reduced carrier emission type
- A. H3E
- B. R3E
- C. J3E
- D. B8E
27. A single sideband suppressed carrier emission type.
- A. H3e
- B. R3E
- C. J3E
- D. B8E
28. Independent sideband emission type
- A. H3E
- B. R3E
- C. J3E
- D. B8E
29. Vestigial sideband emission type
- A. C3F
- B. J3E
- C. R3E
- D. B8E
30. Single sideband full carrier emission type.
- A. R3E
- B. H3E
- C. J3E
- D. B8E
31. Phase modulation emission type.
- A. F3E
- B. F3C
- C. F3F
- D. G3E
32. Which one is not an advantage of SSB over AM?
- A. Power saving
- B. Requires half the bandwidth
- C. Wider area of reception
- D. Better fidelity
33. The advantage of a high level modulated AM transmitter is
- A. Less audio power required
- B. Better fidelity
- C. Higher value of operating power
- D. Less distortion
34. The advantage of a low-level modulated AM transmitter is
- A. Less audio power required
- B. Better fidelity
- C. Higher value of operating power
- D. Less distortion
35. _____ is the bad effect caused by overmodulation in AM transmission.
- A. Increase in noise
- B. Deviation in the operating frequency
- C. Interface to other radio services
- D. Decrease in the output power
36. Which characteristic of a radio receiver refers to its ability to reject an unwanted signal?
- A. Sensitivity
- B. Selectivity
- C. Fidelity
- D. Quality
37. What type of emission is frequency modulation?
- A. F3E
- B. G3E
- C. A3E
- D. B3E
38. AM transmission power increases with ________.
- A. Frequency
- B. Source
- C. Load
- D. Modulation
39. _______ locks the FM receiver to a stronger signal.
- A. Hall effect
- B. Capture effect
- C. Image frequency
- D. Homing
40. What is the highest percentage of modulation for AM?
- A. 50 %
- B. 75 %
- C. 100 %
- D. 80 %
41. In FM, the Carson’s Rule states that the bandwidth is equal to twice the sum of the modulating frequency and ______.
- A. Carrier signal
- B. Modulating signal
- C. Frequency deviation
- D. Image frequency
42. What is the carrier swing of an FM transmitter when modified by 75%?
- A. 53.2 kHz
- B. 48 kHz
- C. 56.25 kHz
- D. 112.5 kHz
43. The modulation system inherently more resistant to noise
- A. Single sideband suppressed carrier
- B. Frequency modulation
- C. Pulse-position modulation
- D. Amplitude shift keying
44. Subcarriers that are arranged so that the channels occupying adjacent frequency bands with some frequency space between them is known as
- A. Guard bands
- B. AM bands
- C. Band gap
- D. Void band
45. Modulation of an RF amplifier carrier results in
- A. Multiple channels
- B. Smaller antennas
- C. Directional propagation
- D. All of the above
46. A process which occurs in the transmitter
- A. Mixing
- B. Modulation
- C. Heterodyning
- D. Demodulation
47. A process which occurs in the receiver
- A. Beating
- B. Modulation
- C. Mixing
- D. Demodulation
48. One part of the transmitter that protects the crystal oscillator from “pulling”.
- A. Buffer amplifier
- B. Modulator
- C. Power amplifier
- D. Antenna coupler
49. What aspect of the carrier is changed by modulation?
- A. Frequency
- B. Phase
- C. Amplitude
- D. Depends on the type of modulation
50. The amplitude of a sine wave which is modulated by a musical program will
- A. Be complex
- B. Contain fundamental frequencies
- C. Contain harmonic frequencies
- D. All of the above
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