A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

41. A communications device that combines transmissions from several I/O devices into one line is a:
a. modifier
b. multiplexer
c. concentrator
d. full-duplex line
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Answer: (b).multiplexer

42. Which of the following technique is used for allocating capacity on a satellite channel using fixed-assignment FDM?
a. Frequency modulation
b. Amplitude modulation
c. Frequency-shift keying
d. Frequency-division multiple access
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Answer: (d).Frequency-division multiple access

43. An ROP would be attached to a
a. simplex channel
b. duplex channel
c. half duplex channel
d. full duplex channel
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Answer: (a).simplex channel

44. The communication mode that supports data in both directions at the same time is
a. simplex
b. half-duplex
c. full-duplex
d. multiplex
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Answer: (c).full-duplex

45. ASK, PSK, FSK, and QAM are examples of _____ encoding.
a. analog-to-digital
b. analog-to-analog
c. digital-to-analog
d. digital-to-digital
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Answer: (c).digital-to-analog

46. Which of the following communications modes support two-way traffic but in only one direction of a time?
a. simplex
b. half-duplex
c. three-quarters duplex
d. All of the above
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Answer: (b).half-duplex

47. In synchronous Time-Division Multiplexing (TDM), the data rate of the link is faster
a. 2 times
b. 3 times
c. 4 times
d. n times
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Answer: (d).n times

48. In statistical Time-Division Multiplexing (TDM), a block of data is usually many bytes while the address is just
a. greater bytes than the block of data
b. few bytes
c. zero byte
d. infinite bytes
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Answer: (b).few bytes

49. The voice channels of the E-4 is
a. 30
b. 120
c. 480
d. 1920
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Answer: (d).1920

50. Telephone companies implement multiplexing
a. TDM
b. FDM
c. WDM
d. DWDM
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Answer: (a).TDM

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