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modulation and demodulation MCQs

Practise focused modulation and demodulation questions with marked answers for exam preparation and subject revision.

modulation and demodulation Mcqs
1. The signal voltage induced in the aerial of a radio receiver is of the order of_____________?
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A. V

B. mV

C. V

D. None of the above

2. In the above question, what is the power in sidebands ?
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A. 8 kW

B. 6 kW

C. 06 kW

D. 9 kW

3. The major advantage of FM over AM is__________________?
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A. Smaller bandwidth

B. Reception is less noisy

C. Small frequency deviation

D. Higher carrier frequency

4. In radio transmission, the medium of transmission is ________________?
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A. None of the above

B. Cable

C. Space

D. An antenna

5. In TV transmission, sound signal is ______________modulated?
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A. None of the above

B. Phase

C. Frequency

D. Amplitude

6. The diode detector in an AM radio receiver is usually found _____________?
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A. After several stages of amplification

B. None of the above

C. After the first RF stage

D. Before the first RF stage

7. In an AM wave useful power is carrier by ______________?
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A. Carrier

B. Sidebands

C. Both sidebands and carrier

D. None of the above

8. The superhetrodyne principle provides selectivity at ______________stage?
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A. audio

B. Before RF

C. IF

D. RF

9. The signal voltage induced in the aerial of a radio receiver is of the order of ________________?
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A. V

B. mV

C. None of the above

D. V
10. In a radio receiver, we generally use .. oscillator as a local oscillator
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A. Phase-shift

B. Hartley

C. Wien-bridge

D. Crystal

11. As the modulation level is increased, the carrier power__________________?
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A. Is decreased

B. None of the above

C. Is increased

D. Remains the same
12. Modulation refers to a low-frequency signal controlling the ________________?
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A. May be any of the above

B. Amplitude of the carrier

C. Frequency of the carrier

D. Phase of the carrier

13. Man made noise are______________ variations?
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A. Amplitude

B. Frequency

C. Phase

D. Both phase and frequency

14. If level of modulation is increased ______________ power is increased?
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A. Carrier as well as sideband

B. Carrier

C. Sideband

D. None of the above

15. If a radio receiver amplifies all the signal frequencies equally well, it is said to have high ________________?
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A. Selectivity

B. Sensitivity

C. Fidelity

D. Distortion

16. If Amin = 40 and Amax = 60, what is the percentage of modulation?
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A. 20 %

B. 50%

C. 40%

D. 10%

17. In the above question, what is the power in sidebands?
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A. 9 kW

B. 8 kW

C. 6 kW

D. 06 kW
18. In superhetrodyne receiver, the input at mixer stage is________________?
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A. IF and RF

B. RF and AF

C. IF and AF

D. RF and local oscillator signal
19. In TV transmission, picture signal is ______________ modulated?
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A. Amplitude

B. Frequency

C. None of the above

D. Phase

20. Superhertodyne principle refers to_________________?
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A. None of the above

B. Using a large number of amplifier stages

C. Obtaining lower fixed intermediate frequency

D. Using a push-pull circuit

21. A 100 V carrier is made to vary between 160 V and 40 V by the signal. What is the modulation factor ?
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A. 3

B. None of the above

C. 6

D. 5

22. A 50 kW carrier is to be amplitude modulated to a level of 85%. What is the carrier power after modulation ?
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A. 5 kW

B. 8 kW

C. 25 kW

D. 50 kW
23. Most of the amplification in a superhetrodyne receiver occurs at ______________stage?
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A. Detector

B. IF

C. Audio amplifier

D. RF amplifier

24. In a radio receiver, noise is generally developed at _______________?
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A. Audio stage

B. IF stage

C. RF stage

D. Receiving antenna

25. The letters AVC stand for ________________?
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A. Audio voltage control

B. Abrupt voltage control

C. Automatic volume control

D. Automatic voltage control

26. In a TRF radio receiver, the RF and detection stages are tuned to______________?
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A. None of the above

B. IF

C. Audio frequency

D. Radio frequency
27. The function of ferrite antenna is to_________________?
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A. Reduce noise

B. Increase the Q of tuned circuit

C. Stabilise d.c. bias

D. Reduce stray capacitance

28. In an AM wave, the majority of the power is in _____________?
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A. Lower sideband

B. Upper sideband

C. None of the above

D. Carrier
29. When the modulating signal controls the frequency of the carrier, we get______________?
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A. Frequency modulation

B. Phase modulation

C. Amplitude modulation

D. May be any one of the above

30. In a transmitter ____________oscillator is used?
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A. Wien-bridge

B. Hartley

C. RC phase-shift

D. Crystal
31. In a superhetrodyne receiver, the difference frequency is chosen as the IF rather than the sum frequency because _________________?
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A. None of the above

B. Only the difference frequency can be modulated

C. The difference frequency is closer to oscillator frequency

D. Lower frequencies are easier to amplify
32. A high Q tuned circuit will permit an amplifier to have high __________________?
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A. Fidelity

B. Sensitivity

C. Frequency range

D. Selectivity
33. Demodulation is done in ________________?
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A. Transmitting antenna

B. Transmitter

C. Radio receiver

D. Receiving antenna

34. The IF is 455 kHz. If the radio receiver is tuned to 855 kHz, the local oscillator frequency is _______________?
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A. 1310 kHz

B. 455 kHz

C. 1520 kHz

D. 1500 kHz

35. In amplitude modulation, the _____________of carrier is varied according to the strength of the signal?
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A. None of the above

B. Amplitude

C. Frequency

D. Phase

36. Over modulation results in ______________?
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A. None of the above

B. Weakening of the signal

C. Distortion

D. Excessive carrier power

37. At 100% modulation, the power in each sideband is _____________ of that of carrier?
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A. 50%

B. 40%

C. 60%

D. 25%
38. In amplitude modulation, bandwidth is ____________ the audio signal frequency?
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A. Four times

B. Thrice

C. Twice

D. None of the above

39. If modulation is 100% then signal amplitude is ____________arrier amplitude?
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A. None of the above

B. Greater than

C. Less than

D. Equal to
40. In pakistan, ______________ modulation is used for radio transmission?
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A. Phase

B. Amplitude

C. Frequency

D. None of the above

41. Modulation is done in____________________
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A. Radio receiver

B. Transmitter

C. None of the above

D. Between transmitter and radio receiver

42. Overmodulation (amplitude) occurs when signal amplitude is _____________ carrier amplitude?
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A. Equal to

B. Greater than

C. None of the above

D. Less than