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MCQ in Modulation Part 1 | ECE Board Exam

MCQ in Modulation Part 1 | ECE Board Exam

This is the Multiples Choice Questions Part 1 of the Series in Modulation as one of the Communications Engineering topic. In Preparation for the ECE Board Exam make sure to expose yourself and familiarize in each and every questions compiled here taken from various sources including but not limited to past Board Examination Questions in Electronic System and Technologies, Communications Books, Journals and other Communications References.

MCQ Topic Outline included in ECE Board Exam Syllabi

  • MCQ in Amplitude Modulation
  • MCQ in Phase Modulation
  • MCQ in Sound Pressure Level
  • MCQ in Frequency Modulation
  • MCQ in Pulse Modulation

Start Practice Exam Test Questions Part 1 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

View Answer:

Answer: Option A

Solution:

2. _______ determines the number of sideband components in FM.

A. carrier frequency

B. modulation frequency

C. modulation index

D. deviation ratio

View Answer:

Answer: Option C

Solution:

3. One of the following transmits only one sideband.

A. H3E

B. R3E

C. A3E

D. B8E

View Answer:

Answer: Option A

Solution:

4. What produces the sidebands on FM?

A. signal amplitude

B. carrier harmonics

C. baseband frequency

D. broadband frequency

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option B

Solution:

6. Mixer is also known as a ________.

A. modulator

B. suppressor

C. converter

D. beater

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option B

Solution:

9. The process of impressing intelligence on the carrier is called

A. modulation

B. detection

C. mixing

D. impression

View Answer:

Answer: Option A

Solution:

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

View Answer:

Answer: Option A

Solution:

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

View Answer:

Answer: Option C

Solution:

12. The difference between the RF carrier and the modulating signal frequencies is called the

A. USB

B. LSB

C. Sideband

D. Carrier frequency

View Answer:

Answer: Option B

Solution:

13. What stage in a radio transmitter isolates the oscillator from the load?

A. Oscillator

B. Buffer

C. Separator

D. Mixer

View Answer:

Answer: Option B

Solution:

14. The frequency of the unmodulated carrier in FM system is

A. modulating frequency

B. center frequency

C. carrier frequency

D. deviation frequency

View Answer:

Answer: Option B

Solution:

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

View Answer:

Answer: Option B

Solution:

16. A carrier signal has

A. constant amplitude

B. a frequency of 20 kHz and above

C. a varying amplitude

D. the information content

View Answer:

Answer: Option B

Solution:

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

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option A

Solution:

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

View Answer:

Answer: Option B

Solution:

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

View Answer:

Answer: Option A

Solution:

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

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option C

Solution:

23. Which is the first radio receiver?

A. TRF receiver

B. Superheterodyne receiver

C. Crystal radio receiver

D. Heterodyne receiver

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option A

Solution:

25. Double sideband full carrier emission type

A. A3J

B. H3E

C. R3A

D. A3E

View Answer:

Answer: Option D

Solution:

26. Single sideband reduced carrier emission type

A. H3E

B. R3E

C. J3E

D. B8E

View Answer:

Answer: Option B

Solution:

27. A single sideband suppressed carrier emission type.

A. H3e

B. R3E

C. J3E

D. B8E

View Answer:

Answer: Option C

Solution:

28. Independent sideband emission type

A. H3E

B. R3E

C. J3E

D. B8E

View Answer:

Answer: Option D

Solution:

29. Vestigial sideband emission type

A. C3F

B. J3E

C. R3E

D. B8E

View Answer:

Answer: Option A

Solution:

30. Single sideband full carrier emission type.

A. R3E

B. H3E

C. J3E

D. B8E

View Answer:

Answer: Option B

Solution:

31. Phase modulation emission type.

A. F3E

B. F3C

C. F3F

D. G3E

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option A

Solution:

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

View Answer:

Answer: Option C

Solution:

36. Which characteristic of a radio receiver refers to its ability to reject an unwanted signal?

A. Sensitivity

B. Selectivity

C. Fidelity

D. Quality

View Answer:

Answer: Option B

Solution:

37. What type of emission is frequency modulation?

A. F3E

B. G3E

C. A3E

D. B3E

View Answer:

Answer: Option A

Solution:

38. AM transmission power increases with ________.

A. Frequency

B. Source

C. Load

D. Modulation

View Answer:

Answer: Option D

Solution:

39. _______ locks the FM receiver to a stronger signal.

A. Hall effect

B. Capture effect

C. Image frequency

D. Homing

View Answer:

Answer: Option B

Solution:

40. What is the highest percentage of modulation for AM?

A. 50 %

B. 75 %

C. 100 %

D. 80 %

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option C

Solution:

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

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option B

Solution:

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

View Answer:

Answer: Option A

Solution:

45. Modulation of an RF amplifier carrier results in

A. Multiple channels

B. Smaller antennas

C. Directional propagation

D. All of the above

View Answer:

Answer: Option D

Solution:

46. A process which occurs in the transmitter

A. Mixing

B. Modulation

C. Heterodyning

D. Demodulation

View Answer:

Answer: Option B

Solution:

47. A process which occurs in the receiver

A. Beating

B. Modulation

C. Mixing

D. Demodulation

View Answer:

Answer: Option D

Solution:

48. One part of the transmitter that protects the crystal oscillator from “pulling”.

A. Buffer amplifier

B. Modulator

C. Power amplifier

D. Antenna coupler

View Answer:

Answer: Option A

Solution:

49. What aspect of the carrier is changed by modulation?

A. Frequency

B. Phase

C. Amplitude

D. Depends on the type of modulation

View Answer:

Answer: Option D

Solution:

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

View Answer:

Answer: Option D

Solution:

Questions and Answers in Modulation Series

Following is the list of multiple choice questions in this brand new series:

MCQ in Modulation
PART 1: MCQ from Number 1 – 50                        Answer key: PART 1
PART 2: MCQ from Number 51 – 100                   Answer key: PART 2
PART 3: MCQ from Number 101 – 150                 Answer key: PART 3
PART 4: MCQ from Number 151 – 200                 Answer key: PART 4
PART 5: MCQ from Number 201 – 250                 Answer key: PART 5
PART 6: MCQ from Number 251 – 300                 Answer key: PART 6
PART 7: MCQ from Number 301 – 350                 Answer key: PART 7
PART 8: MCQ from Number 351 – 400                 Answer key: PART 8
PART 9: MCQ from Number 401 – 450                 Answer key: PART 9
PART 10: MCQ from Number 451 – 500                 Answer key: PART 10

Complete List of MCQ in Communications Engineering per topic

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