Anna University Chennai 2010-2nd Sem B.E Communication Engineering Anna University /B.Tech EC-1351 Digital Communication (E.C.E ) 6th semester - - Question Paper

B.E/B.Tech DEGREE EXAMINATION,APRIL/MAY 2010
6th Semester
Electronics and Communication Engineering
EC 1351 –DIGITAL COMMUNICATION
(Regulation 2004)
(Common to B.E(Part-Time) 5th Semester Regulation 2005)
Time:3 hours Maximum:100 marks
ans ALL ques..
PART A-(10 * 2=20 marks)
1. What are the 2 kinds of quantization fault that occur in delta modulation?
2. Sate the advantage of adaptive delta modulation over delta modulation?
3. What is meant by correlative level coding?
4. Define fault probability.
5. Differentiate base band transmission from pass band transmission.
6. Define MSK.
7. Define Hamming weight and Minimum Hamming distance.
8. What is the function of interleaver?
9. Define Gold Theorem.
10. Write down the expression for jamming margin.

PART-B(5 *16=80 marks)
11. (a)(i) discuss the working of differential PCM and hence derive the expression for
signal to noise ratio. (12 marks)
(ii) Write a note on multiplexing.(4 marks)
(or)
(b)(i) discuss the non-uniform quantization.(6 marks)
(ii) discuss the operation of PCM and Delta modulation systems.(10 marks)
12. (a)(i) discuss in detail M-ary base band system.(10 marks)
(ii) Write briefly about eye trends.(6 marks)
(or)
(b)(i) find the expression for Nyquist criteria for distortionless base band
transmission for zero ISI .
(ii) discuss about adaptive equalization.(6 marks)
13. (a)(i) Derive the expression for probability of fault of BPSK and QAM systems.
(16 marks)
(or)
(b)(i) discuss the working of DPSK scheme. With the help of suitable circuit (6 marks)
(ii) discuss carrier and symbol synchronization.(10 marks)
14. (a)(i) explain the encoding turbo codes and their performance.(8 marks)
(ii) Draw the state diagram of ½ rate convolution code shown below:
(or)
(b)(i) With an example show how viterbi algorithm is used for decoding convolutional
codes.(10 marks)
(ii) Write short notes on: Cyclic Redundancy Check codes.( six marks)
15.(a)(i) discuss the frequency –hop spread spectrum technique in detail.(10 marks)
(ii) discuss the properties of PN sequence.(6 marks)
(or)
(b)(i) Derive the expression for probability of fault of direct sequence spread BPSK
system.
(10 marks)
(ii) Write about the maximal length and gold codes.(6 marks).
***************************************

Earning:   Approval pending.