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Electrical measurements MCQ Quiz Hub
Digital Communications MCQs set-2
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1. Find the 8-ary waveform for the word ‘HAPPY’.
4040020246
0440020246
6420200440
None of the mentioned
2. Find the 32-ary waveform for the word ‘HAPPY’.
280856
658082
288056
None of the mentioned
3. What are the characteristics of an ideal transmission line?
Different amplitude
No distortion
Time delay
All of the mentioned
4. The point at which the output signal power has fallen to 0.707 of its peak value is called as _____
3db point
Half power point
3db & Half power point
None of the mentioned
5. The ratio of the filter bandwidth at -60db and -6db amplitude response point is called as _____
Half point factor
Normalized factor
Shape factor
None of the mentioned
6. As the order of the filter increases, the cost ______ and complexity ______
Increases, increases
Increases, decreases
Decreases, increases
Decreases, decreases
7. Which filter has maximum flatness?
Chebyshev filter
Butter-worth filter
High pass filter
Normalized filter
8. The measure of the width of the main lobe is called as ________
Null to null bandwidth
Half power bandwidth
Normalized bandwidth
Absolute bandwidth
9. SQNR can be improved by _______ sampling rate.
Increasing
Decreasing
Does not depend
None of the mentioned
10. Which offers better SQNR?
Delta modulation
PCM
Delta modulation & PCM
None of the mentioned
11. Two functions are called as orthogonal if on integrating the product we get
One
Zero
Infinity
None of the mentioned
12. Eigen functions are not orthogonal.
True
False
13. Shot noise is produced by
Electrons
Photons
Electrons & Photons
None of the mentioned
14. Shot noise is avoidable when current is
Zero
One
Infinity
None of the mentioned
15. Which occurs due to equilibrium fluctuations?
Thermal noise
Johnson noise
Thermal & Johnson noise
None of the mentioned
16. Flicker noise is called as
White noise
Pink noise
Brown noise
None of the mentioned
17. Which has the same power spectral density?
White noise
Brown noise
White & Brown noise
None of the mentioned
18. Which noise is useful for dithering?
White noise
Pink noise
Brown noise
None of the mentioned
19. Capacity of a channel can be increased by
Increasing channel bandwidth
Increasing signal power
Increasing channel bandwidth &signal power
None of the mentioned
20. Capacity of the channel can be increased by reducing in band noise power.
True
False
21. Thermal noise is a wide sense stationary process.
True
False
22. The maximum likelihood function is
Positive
Negative
Any of the mentioned
None of the mentioned
23. Matched filtering operation includes
Spectral phase matching
Spectral amplitude matching
Spectral phase & amplitude matching
None of the mentioned
24. Matched filter is
Linear
Non linear
Linear & Non linear
None of the mentioned
25. Which consists of less ISI?
Nyquist filter
Raised cosine filter
Nyquist & Raised cosine filter
None of the mentioned
26. Digital communication is _______ to environmental changes?
Less sensitive
More sensitive
Does not depend
None of the mentioned
27. Advantages of digital communication are
Easy multiplexing
Easy processing
Reliable
All of the mentioned
28. What is necessary for digital communication?
Precision timing
Frame synchronization
Character synchronization
All of the mentioned
29. What are the disadvantages of digital communication?
Needs more bandwidth
Is more complex
Needs more bandwidth & Is more complex
None of the mentioned
30. Examples of digital communication are
ISDN
Modems
Classical telephony
All of the mentioned
31. Which system uses digital transmission?
ISDN
LANs
ISDN & LANs
None of the mentioned
32. The interval of frequencies outside which the spectrum is zero is called as ________
null to null bandwidth
normalized bandwidth
absolute bandwidth
none of the mentioned
33. The attenuation level in bounded power spectral density is
35
50
35 & 50
none of the mentioned
34. Synchronization available in digital communication are
Symbol synchronization
Frame synchronization
Carrier synchronization
All of the mentioned
35. Digital system includes
Better encryption algorithm
Difficult data multiplexing
All of the mentioned
None of the mentioned
36. Analog to digital conversion includes
Sampling
Quantization
Sampling & Quantization
None of the mentioned
37. What are the main features of a receiver?
Synchronization
Multiple parallel receiver chain
Synchronization & Multiple parallel receiver chain
None of the mentioned
38. What conditions must be fulfilled in a good digital communication system?
High data rate
High fidelity
Low transmit power
All of the mentioned
39. Wired channels are
Lossy
Lossless
Lossy & Lossless
None of the mentioned
40. The equivalent temperature in a receiver design must be kept
Low
High
Does not affect the receiver
None of the mentioned
41. Which corrects the sampling time problem in a digital system?
Interpolator
Decimator
Equalizer
Filter
42. What are the main features of a transmitter?
Higher clock speed
Linear power amplifier
Directional antennas
All of the mentioned
43. Transmission media used in low frequency band are
Air
Water
Copper cable
All of the mentioned
44. Transmission media used for medium frequency band are
Coaxial cable
Copper cable
Optical fiber
All of the mentioned
45. Matched filter technique is used to
Increase SNR
Decrease SNR
SNR is not affected
None of the mentioned
46. Matched filter can also be used as least squares estimator.
True
False
47. Digital communication system can handle
Analog signals
1D signals
2D signals
All of the mentioned
48. The information source of a digital communication system can be
Packetized
Continuous
Packetized & Continuous
None of the mentioned
49. Which are the common transmission media used in digital communication system?
Coaxial cable
Twisted copper cable
Radio frequency bands
All of the mentioned
50. The basic transmission-reception system is a ______ system.
Two block system
Three block system
Four block system
None of the mentioned
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