MCQs on Modulation and Multiplexing Techniques

MCQs on Modulation and Multiplexing Techniques

MCQs on Modulation and Multiplexing Techniques for Satellite Link, MCQs on Satellite Link, Multiplexing MCQ, Modulation MCQ, Objective Questions on Multiplexing for satellite link, Objective Questions on Modulation for satellite link.

Objective Type Questions

1. Indicate the false statement regarding the advantages of SSB over double side band, full carrier AM  

  • more channel space is available
  • the signal is more noise resistant
  • transmitter circuit must be more stable, giving better reception
  • much less power is required for the same signal strength

Answer: transmitter circuit must be more stable, giving better reception

2. one of the following can not be used to demodulate SSB

  • product detector
  • diode balanced modulator
  • bipolar transistor balanced modulator
  • complete phase shift generator

Answer: bipolar transistor balanced modulator

3. FM discriminator changes the FM signal into

  • AM signal
  • FM signal
  • PM signal
  • None of these

Answer: AM signal

4. The commonly employed filter in SSB generation is

  • high pass filter
  • mechanical filter
  • RC filter
  • LC filter

Answer: mechanical filter

5. what should be the oscillator frequency for tuning in 710 KHz on an AM radio with a 455 KHz IF :

  • 1165 KHz
  • 1015 KHz
  • 255 KHz
  • 127.5 KHz

Answer: 1165 KHz

6. The band width required for base band signals for FM radio is generally

  • 0.3 to 3 KHz
  • 0.5 to 1.5 KHz
  • upto 15 KHz
  • upto 15 MHz

Answer: upto 15 KHz

7. A carrier is amplitude modulated by two sine waves of different frequencies upto 40% and 60%. The resulting overall modulation index is:

  • 1
  • 0.72
  • 0.4
  • 0.6

Answer: 1

8. The following is an indirect method of generating FM:

  • Reactive FM modulator
  • Armstrong modulation
  • Varactor diode modulation
  • Reactance BJT modulator

Answer: Armstrong modulation

9. The difference between a DSB and a SSB transmission is

  • DSB has a carrier and two side bands and SSB, a carrier and side band.
  • DSB has two side bands and SSB one side bands.
  • DSB may or may not have a carrier with two side bands and SSB either of the two side band without carrier.
  • DSB has a carrier and two side bands and SSB without carrier and two different side bands.

Answer: DSB may or may not have a carrier with two side bands and SSB either of the two side band without carrier.

10. Companding is used

  • To protect small signals in PCM from quantizing distortion
  • To overcome quantize noise in PCM
  • To overcome impulse noise
  • None of these

Answer: To protect small signals in PCM from quantizing distortion

11. The modulation index of an AM signal is increased from 0 to 1. The carrier power

  • Remains unchanged
  • Gets doubled
  • Increased by 50%
  • Gets quadrupled

Answer: Increased by 50%

12. Frequency Shift Keying is basically a method involving

  • Amplitude Modulation
  • Frequency Modulation
  • Phase Modulation
  • None of these

Answer: Frequency Modulation

13. Probability density function of thermal noise is

  • Binomial
  • Gaussian
  • Poisson
  • None of these

Answer: Gaussian

14. Frequency Shift Keying is commonly used in

  • Radio Transmission
  • Telegraphy
  • Telephony
  • None of these

Answer: Telegraphy

15. The saving in power in a SSB system is

  • 100%
  • 75%
  • >=75%
  • 50%

Answer: >=75%

16. The saving in power in DSBSC system modulated at 80% is

  • Nil
  • 80%
  • 88.3%
  • 50%

Answer: Nil

17. Pre-Emphasis is used to amplify

  • Low Frequency
  • High Frequency
  • Both the above
  • None of these

Answer: Both the above

18. In communication system, sampling technique leads to

  • Cheaper equipment
  • Better efficiency
  • Higher speed of communication
  • Simpler operation

Answer: Better efficiency

19. De-emphasis circuit is used

  • After Modulation
  • Prior to Modulation
  • To De-emphasis low frequency components
  • To De-emphasis high frequency components

Answer: To De-emphasis low frequency components

20. A scheme in which several channels are interleaved and then transmitted together is known as

  • Frequency Division Multiplexing
  • Time Division Multiplexing
  • A Group
  • A Super Group

Answer: A Super Group

21. In a Broadcast Super Heterodyne Receiver

  • The RF Amplifier normally works at 455 KHz above the carrier frequency
  • Mixer input must be tuned to the signal frequency
  • Local oscillator operates below the signal frequency
  • Local oscillator frequency is normally double the IF

Answer: Local oscillator frequency is normally double the IF

22. Pulse Width Modulation may be generated

  • By differentiating Pulse Position Modulation
  • With a Mono Stable Multivibrator
  • By Integrating the signal
  • With a Free Running Multivibrator

Answer: By differentiating Pulse Position Modulation

23. Which of the following is an indirect way of generating FM

  • Reactance FET Modulator
  • Varactor Diode
  • Armstrong Modulation
  • Reactance Bipolar transistor Modulator

Answer: Varactor Diode

24. Which of the following system is digital

  • Pulse Position Modulation
  • Pulse Code Modulation
  • Pulse Width Modulation
  • Pulse Frequency Modulation

Answer: Pulse Width Modulation

25. Time Division Multiplex

  • Can be used with PCM only
  • Combines five groups into a super group
  • Stacks 24 channel in adjacent frequency slots
  • Interleave pulses belonging to different transmissions

Answer: Combines five groups into a super group

26. Which of the following Pulse Modulation System is analog

  • Delta
  • PCM
  • Differential PCM
  • PWM

Answer: PWM

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