PG – 505

*PG505*

III Semester M.Sc. Degree Examination, December 2013/January 2014 ELECTRONIC SCIENCE EL 303 : Electronic Communication Systems Time : 3 Hours

Max. Marks :80

Instructions : i) Answer all questions from Part A and four full questions from Part B. ii) Missing data may be assumed suitably. PART – A 1. State and prove sampling theorem for low pass signals.

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2. Compare TDM and FDM Concepts.

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3. Explain Geosynchronous orbit.

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4. What are the advantages of M-ary signaling scheme compared to Binary ?

4

5. Explain Huffman coding steps with three source symbols.

4

PART – B 6. a) Explain the generation and detection of PSK system.

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b) What is the need of going for keying techniques ?

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7. a) Highlight different types of errors experienced in delta modulation pictorially Explain. How do you eliminate them ?

6

b) Derive signal-to-noise ratio for PCM system.

9

8. a) List the properties of matched filter receiver.

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b) Consider a (6,3) linear block code whose generator matrix is ⎡ 1 0 0 0 1 1⎤ G = ⎢ 0 1 0 1 0 1⎥ ⎢ ⎥ ⎢⎣0 0 1 1 1 0 ⎥⎦

i) Find all the code vectors of this code ii) Find the parity check matrix for this code iii) Find the minimum distance of this code.

8 P.T.O.

*PG505*

PG – 505 9. a) What are the factors responsible for loss in optical fibers ?

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b) What are the different splicing methods ? Explain.

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10. a) Calculate the radius of a circular orbit for which the period is 1 day ?

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b) Calculate the propagation delay when a satellite which is revolving around the earth at a height of 36000 kms from the earth.

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c) Explain different types of satellites.

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11. Write short notes on any three of the following : a) Transponders b) Correlation receiver c) Antenna look angles d) ALOHA protocols e) PAM.

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(5 each)