Anna University Chennai 2007 M.E CO 1602 - MODERN DIGITAL COMMUNICATION TECHNIQUES - Question Paper

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G 6139
M.E. DEGREE EXAMINATION, MAY/JUNE 2007.
First Semester
Communication Systems
CO 1602 - MODERN DIGITAL COMMUNICATION TECHNIQUES
(Common to ME-Digital Communication and Network Engineering,
ME-Computer and Communication and ME-Optical Communication)
(Regulation 2005)
Time : 3 hours
Maximum: 100 marks

ans ALL ques..
PART A - (10 x two = 20 marks)

1. Define memoryless channel.

2. How will you generate the convolutional codes?

3. What are the general characteristics of a coherent receiver?

4. What is a multi dimensional signal? provide an example.

5. When a channel is called as Ricean channel?

6. What are the causes for ISI?

7. The bandwidth of the media is four KHz and the SNR is 3100. obtain the channel capacity.

8. What is a Golay Code?

9. Define coding gain. How to increase it?

10. Compare the Maximum likelihood and Viterbi algorithm methods for decoding.




PART B - (5 x 16 = 80 marks)

11. (a) (i) What is an M-ary Markov source? discuss. (6)

(ii) explain in detail about continuous phase modulation. (10)

or

(b) D~scribe the scalar and vector communication over memoryless channel. (16)

12. (a) With a neat block diagram discuss the function of DPSK and MPSK demodulators. (16)

Or

(b) (i) explain the various kind of IQ modulation.(10)

(ii) define the function of M - FSK receiver. (6)

13. (a) (i) What is an eye pattern? How it is used to know the info about a channel. (6)

(ii) define the various equalization techniques used for band limited channels. (10)

Or

(b) Derive the decision rule for optimum demodulation of digital signal in the presence of IS I and AWGN(16)

14. (a) (i) What is a matched filter? discuss the various properties of it. (10)

(ii) discuss the concept of direct sequence spread spectrum. (6)

Or

(b) With a suitable example discuss the Hamming and cyclic codes. (16)

15. (a) With an example define the following: (16)
(i) State diagram
(ii) Tree diagram
(iii) Trellis diagram.

Or

(b) Write short notes on the following:
(i) Decoding technique using maximum likelihood (8)
(ii) Turbo coding (8)

G 6139

Earning:   Approval pending.