Angle Modulation MCQ | Engineering MCQ

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Angle Modulation MCQ

Angle Modulation MCQ, Multiple Choice Question on Angle Modulation, Objective Question with the answer on Angle Modulation, GATE Questions on Angle Modulation, Angle Modulation Multiple Choice Question, Angle Modulation MCQ, Engineering MCQ

Multiple Choice Questions

Q.1. The message carrying efficiency is best in

  • FM
  • AM
  • AM-SC
  • Phase modulation

Answer: AM-SC

Q.2. Following is not advantage of FM over AM

  • noise immunity
  • fidelity
  • capture effect
  • sputtering effect

Answer: sputtering effect

Q.3. The modulating frequency in frequency modulation is increased from 10 kHz to 20 kHz. The bandwidth is

  • doubled
  • halved
  • increased by 20 kHz
  • increased tremendously

Answer: increased by 20 kHz

Q.4. A narrowband FM does not have the following feature

  • it has two sidebands
  • both sidebands are equal in amplitude
  • both sidebands have same phase difference with respect to carrier
  • it does not show amplitude variations

Answer: both sidebands have same phase difference with respect to carrier

Q.5. In time division multiplexing, the FM detector has _____ noise contribution as compared to phase modulation.

  • more
  • less
  • equal
  • unknown

Answer: less

Q.6. In a single tone FM discriminator S_{0}/N_{0} is

  • proportional to deviation
  • proportional to cube of deviation
  • inversely proportional to deviation
  • proportional to square of deviation

Answer: proportional to square of deviation

Q.7. Assuming other parameters unchanged, if the modulating frequency is halved in a modulating systems, the modulation index is doubled. The modulation system is

  • AM
  • FM
  • phase modulation
  • angle modulation

Answer: FM

Q.8. A PLL can be used to demodulate

  • an AM signal
  • a USB-SC signal
  • an FM signal
  • a PCM signal

Answer: an FM signal

Q.9. In a commercial FM broadcast system, the modulating signal frequency is limited to about

  • 3.4 kHz
  • 5 kHz
  • 15 kHz
  • 20 kHz

Answer: 15 kHz

Q.10. The bandwidth of an FM signal requires at least 10 times the bandwidth of the _______  signal.

  • carrier
  • modulating
  • AM
  • PM

Answer: modulating

Q.11. A narrowband FM does not have the following feature

  • it does not show any amplitude variations
  • it has two sidebands
  • both sidebands are equal in amplitude
  • both sidebands have identical phase difference with respect to currier

Answer: both sidebands have identical phase difference with respect to currier

Q.12. If the modulating frequency is halved in a modulating system, the modulation index is doubled. Assuming other parameters same, the system is

  • AM
  • Angle modulation
  • FM
  • PM

Answer: FM

Q.13. The amplitude spectrum output of a modulator consists of the carrier frequency, lower sideband frequency, and upper sideband frequency. The modulator is

  • AM
  • AM or/and narrowband FM
  • wideband FM
  • narrowband or/and wideband FM

Answer: AM or/and narrowband FM

Q.14. The instantaneous frequency in an angle modulated signal expressed as x_{c}(t)=10\cos \left [ 200\Pi t+\frac{\Pi }{3} \right ] is ________  Hz.

  • 400
  • 200
  • 100
  • 50

Answer: 100

Q.15. Consider x_{c}(t)=10\cos \left [ 10^{8}\Pi t+5\sin 2\Pi (10^{4})t \right ], The maximum phase deviation and  maximum frequency deviation is __________ and ____________, respectively.

  • 5 radians, 5 kHz
  • 5/2π radians, 5 kHz
  • 5 radians, 5/2π kHz
  • cannot be determined

Answer: 5 radians, 5 kHz

Q. 16. The phase information of a sinusoidal signal can be obtained by ___________ frequency with time.

  • differentiating
  • integrating
  • convolving
  • multiplying

Answer: integrating

Q.17. For wideband FM, the frequency-modulation index is

  • approximately unity
  • much less than unity
  • much greater than unity
  • infinity

Answer: much greater than unity

Q.18. A high-frequency carrier signal is frequency modulated using a modulating signal v_{m}(t)=V_{m}\sin (10000\Pi t). The FM signal has frequency deviation of 5 kHz. Its modulation index is

  • 0.5
  • 1
  • 2
  • 5

Answer: 1

Q.19. A carrier signal is frequency modulated by v_{m}(t)=V_{m}\sin (2\Pi \times 2000t). The frequency-modulation index is 1. The FM signal has frequency deviation of __________ .

  • 1 kHz
  • 2 kHz
  • 4 kHz
  • 0.5 kHz

Answer: 2 kHz

Q.20. A 108 MHz carrier signal is frequency modulated by sinusoidal modulating signal. The maximum frequency deviation is 100 kHz. The approximate transmission bandwidth of the FM signal is __________   if the frequency of the modulating signal is 1 kHz.

  • 2 kHz
  • 100 kHz
  • 101 kHz
  • 200 kHz

Answer: 200 kHz

Q.21. A 108 MHz carrier signal is frequency modulated by sinusoidal modulating signal. The maximum frequency deviation is 100 kHz. The approximate transmission bandwidth of the FM signal is ______  if the frequency of the modulating signal is 500 kHz.

  • 200 kHz
  • 500 kHz
  • 1 MHz
  • 1.2 MHz

Answer: 1 MHz

Q.22. An FM modulator has frequency deviation sensitivity of 1.5 kHz/V. The carrier signal is modulated by the modulating signal having peak amplitude of 4 V and modulating frequency of 1 kHz. The frequency modulation index of FM signal is

  • 6
  • 4
  • 1.5
  • 1

Answer: 6

Q.23. In a commercial TV broadcast station, the sound portion of TV signal is frequency modulated with a maximum frequency deviation of 50 kHz and a maximum modulating-signal frequency of 15 k Hz. The deviation ratio is

  • 33
  • 0.3
  • 750
  • 100

Answer: 33

Q.24. A sinusoidal 400 Hz modulating signal of 2 V amplitude frequency modulates a carrier and produces 70 kHz frequency deviation. The frequency sensitivity is given by

  • 140 kHz per V
  • 70 kHz per V
  • 72 kHz per V
  • 35 kHz per V

Answer: 35 kHz per V

Q.25. In a modulator, it is found that the amplitude spectrum consists of a component fc, the carrier frequency and one component each at fc + fs, and fc – fs. Where fs, is the modulating signal frequency. The modulator used is

  • AM
  • AM and/or narrowband FM
  • FM
  • PAM

Answer:  AM and/or narrowband FM

Q.26. The frequency deviation ratio plays the same role for sinusoidal modulating signal as the frequency-modulation index plays for arbitrary modulating signal.

  • True
  • False

Answer: True

Q.27. Frequency modulation is a linear modulation technique.

  • True
  • False

Answer: False

Q.28. The amplitude of the modulated carrier signal does not carry any information in phase modulation.

  • True
  • False

Answer: True

Q.29. Theoretically an FM signal has an infinite bandwidth.

  • True
  • False

Answer: True

Q.30. In phasor representation of FM, the angle of carrier phasor is varied while in AM the length of the carrier phasor is varied.

  • True
  • False

Answer: True

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