Quiznetik

Communication Engineering | Set 3

1. Coherent PSK and non coherent orthogonal FSK have a difference of               in PB.

Correct : C. 4db

2. Which is easier to implement and is preferred?

Correct : B. non coherent system

3. Which is the main system consideration?

Correct : D. all of the mentioned

4. Self information should be

Correct : A. positive

5. The unit of average mutual information is

Correct : A. bits

6. When probability of error during transmission is 0.5, it indicates that

Correct : C. channel is very noisy & no information is received

7. The event with minimum probability has least number of bits.

Correct : B. false

8. The method of converting a word to stream of bits is called as

Correct : B. source coding

9. When the base of the logarithm is 2, then the unit of measure of information is

Correct : A. bits

10. When X and Y are statistically independent, then I (x,y) is

Correct : B. 0

11. The self information of random variable is

Correct : C. infinite

12. Entropy of a random variable is

Correct : C. infinite

13. Which is more efficient method?

Correct : B. encoding block of symbols

14. Lempel-Ziv algorithm is

Correct : A. variable to fixed length algorithm

15. While recovering signal, which gets attenuated more?

Correct : B. high frequency component

16. Mutual information should be

Correct : C. positive & negative

17. ASCII code is a

Correct : A. fixed length code

18. Which reduces the size of the data?

Correct : A. source coding

19. In digital image coding which image must be smaller in size?

Correct : B. output image

20. Which coding method uses entropy coding?

Correct : B. lossy coding

21. Which achieves greater compression?

Correct : B. lossy coding

22. Which are uniquely decodable codes?

Correct : A. fixed length codes

23. A rate distortion function is a

Correct : B. convex function

24. Which of the following algorithms is the best approach for solving Huffman codes?

Correct : B. greedy algorithm

25. How many printable characters does the ASCII character set consists of?

Correct : C. 100

26. Which bit is reserved as a parity bit in an ASCII set?

Correct : C. eighth

27. How many bits are needed for standard encoding if the size of the character set is X?

Correct : A. log x

28. The code length does not depend on the frequency of occurrence of characters.

Correct : B. false

29. From the following given tree, what is the code word for the character ‘a’?

Correct : A. 011

30. From the following given tree, what is the computed codeword for ‘c’?

Correct : C. 110

31. What will be the cost of the code if character ci is at depth di and occurs at frequency fi?

Correct : C. ∑fidi

32. An optimal code will always be present in a full tree.

Correct : A. true

33. The type of encoding where no character code is the prefix of another character code is called?

Correct : B. prefix encoding

34. What is the running time of the Huffman encoding algorithm?

Correct : C. o(c log c)

35. What is the running time of the Huffman algorithm, if its implementation of the priority queue is done using linked lists?

Correct : D. o(c2)

36. Notch is a

Correct : C. band stop filter

37. Sin wave is

Correct : B. periodic signal

38. What is the role of channel in communication system?

Correct : A. acts as a medium to send message signals from transmitter to receiver

39. Sum of a periodic and aperiodic signal always be an aperiodic signal.

Correct : B. false

40. Noise is added to a signal

Correct : A. in the channel

41. Agreement between communication devices are called

Correct : C. protocol

42. What is the advantage of superheterodyning?

Correct : A. high selectivity and sensitivity

43. Low frequency noise is

Correct : A. flicker noise

44. Relationship between amplitude and frequency is represented by

Correct : C. frequency-domain plot

45. A function f(x) is even, when?

Correct : B. f(x) = f(-x)

46. The minimum nyquist bandwidth needed for baseband transmission of Rs symbols per second is

Correct : C. rs/2

47. The capacity relationship is given by

Correct : A. c = w log2 ( 1+s/n )

48. Which parameter is called as Shannon limit?

Correct : B. eb/n0

49. Entropy is the measure of

Correct : A. amount of information at the output

50. Equivocation is the

Correct : A. conditional entropy

51. For a error free channel, conditional probability should be

Correct : A. zero

52. Average effective information is obtained by

Correct : A. subtracting equivocation from entropy

53. Turbo codes are

Correct : A. forward error correction codes

54. Components used for generation of turbo codes are

Correct : C. inter leavers & punching pattern

55. Decoders are connected in series.

Correct : A. true

56. The inter leaver connected between the two decoders is used to

Correct : B. scatter error bursts

57. In soft decision approach what does -127 mean?

Correct : B. certainly zero

58. In soft decision approach 100 means?

Correct : D. very likely one

59. In soft decision approach 0 represents

Correct : D. could be either zero or one

60. In layering, n layers provide service to

Correct : C. n+1 layer

61. Which can be used as an intermediate device in between transmitter entity and receiver entity?

Correct : D. all of the mentioned

62. Which has comparatively high frequency component?

Correct : C. square wave

63. Which has continuous transmission?

Correct : B. synchronous

64. Which requires bit transitions?

Correct : B. synchronous

65. In synchronous transmission, receiver must stay synchronous for

Correct : C. 9 bits

66. How error detection and correction is done?

Correct : D. by adding redundancy bits

67. Which is more efficient?

Correct : B. cyclic redundancy check

68. Which can detect two bit errors?

Correct : B. cyclic redundancy check

69. CRC uses

Correct : C. multiplication & binary division

70. Block codes can achieve a larger coding gain than convolution coding.

Correct : B. false

71. Which of the following indicates the number of input bits that the current output is dependent upon?

Correct : A. constraint length

72. Which of the following is not a way to represent convolution code?

Correct : D. linear matrix

73. Which of the following is not an algorithm for decoding convolution codes?

Correct : D. ant colony optimization

74. Fano’s algorithm searches all the paths of trellis diagram at same time to find the most probable path.

Correct : B. false

75. Which of the following is not an advantage of Fano’s algorithm in comparison to Viterbi’s algorithm?

Correct : D. small delays

76. In comparison to stack algorithm, Fano’s algorithm is simpler.

Correct : B. false

77. Which of the following is not an error correction and detection code?

Correct : C. passive codes

78. Which decoding method involves the evaluation by means of Fano’s algorithm?

Correct : B. sequential decoding

79. In Viterbi’s algorithm, the selected paths are regarded as

Correct : A. survivors

80. Pseudorandom signal                  predicted.

Correct : A. can be

81. The properties used for pseudorandom sequence are

Correct : D. all of the mentioned

82. The shift register needs to be controlled by clock pulses.

Correct : A. true

83. A linear feedback shift register consists of

Correct : D. all of the mentioned

84. If the initial pulse of 1000 is fed to shift register, after how many clock pulses does the sequence repeat?

Correct : A. 15

85. The sequences produced by shift register depends on

Correct : D. all of the mentioned

86. For maximal length sequence, the sequence repetition clock pulses p is given by

Correct : B. 2n -1

87. For any cyclic shift, the auto-correlation function is equal to

Correct : B. -1/p

88. Which method is better?

Correct : B. to share different bandwidth

89. Pulse jammer consists of

Correct : B. pulse modulated band-limited noise

90. Which are the design options for anti jam communicator?

Correct : D. all of the mentioned

91. The ratio (J/S)reqd gives the measure of

Correct : B. invulnerability to interference

92. The system should have

Correct : C. larger (j/s)reqd & greater system’s noise rejection capability

93. The broadband jammer jams the entire

Correct : B. wss

94. To increase error probability, the processing gain should be

Correct : A. increased

95. Which jamming method produces greater degradation?

Correct : B. partial jamming

96. The jammer which monitors a communicator’s signal is known as

Correct : C. frequency follower & repeat back jammers

97. DS/BPSK includes

Correct : C. despreading & demodulation

98. In direct sequence process which step is performed first?

Correct : A. de-spreading

99. Chip is defined as

Correct : A. shortest uninterrupted waveform

100. Processing gain is given as

Correct : C. wss/r & rch/r