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D R5985

Reg No.: Name:

APJ ABDUL KALAM TECHNOLOGICAL a Sa
FIFTH SEMESTER B.TECH DEGREE EXAMINATION, DECEMBER 2018
Course Code: CS 307
Course Name: DATA COMMUNICATION

Max. Marks: 100 Duration: 3 Hours
PARTA .
Answer all questions, each carries3 marks. Marks
1 What are the three parameters that represent a general sine wave? Explain with (3)
suitable figures.
2 Which wireless propagation is suitable for satellite communication? Justify (3)
your answer.
3 How the construction of optical fibre helps in reducing the interference? (3)
the structure of optical fibre.
4 Discuss the significance of SNR in determining the performance of a data (3)
communication system.
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PART B
Answer any two full questions, each carries 9 marks.
5 9) Explain the role of Shannon capacity formula in determining the channel (4)

capacity.

b) Suppose the spectrum of a channel is between 3MHz and 4MHz and SNRgp is (5)
24 dB. What is the capacity of the channel? Based on Nyquist’s formula, how
many signalling levels are required?
6 a) Explain different wireless propagation modes with suitable diagrams. (6)
b) Given a receiver with an effective noise temperature of 300 K and a 12-MHz (3)
bandwidth, what is the thermal noise level at the receiver’s output?

7 2) With the help of suitable diagrams, differentiate multi-mode and single-mode (6)
optical fibres. How are the rays propagated in step-index and graded-index
multi-mode fibres?

b) A signal travels from point A 10 point B through a transmission channel that (3)
has -0.4dB/km loss. If the signal at A has a power of 3mW, what is the power
of the signal at point B which is 10 km away from A?

PART C
Answer all questions, each carries 3 marks.
8 Compare the terms signal element and data element with suitable diagrams. (3)
9 Show the equivalent square wave pattern of the bit string 00110101 using (3)
NRZ-I , NRZL and Manchester encoding schemes.
10 Which of the multiplexing technique is suitable for fiber-optics links? Explain (3)
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