----------------------- Page 1----------------------Code: 9D38204 M.Tech - II Semester Supplementary April/May 2012 Examinatio ns (for students itted in 2009- 10 & 2010-11 only) CODING THEORY & TECHNIQUES (Digital Electronics & Communications S ystems) Time: 3 hours Max. Marks: 60 Answer any FIVE Ques tions All Questions carry equa l marks

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1.

Define and (a) (b) (c)

explain the following Generator matrix. Systematic linear block codes. Parity check matrix.

2.

(a) (b)

Explain with example hamming codes and perfect codes. Write about weight enumerators and Mac –Williams identities.

3. es.

(a)

Explain in briefly about cyclic codes and decoding of cyclic cod

(b)

Write about algebraic structures of cyclic codes.

(a) (b)

Write about encoding of convolutional codes. Explain in detail likelihood decoding of convolutional codes.

4. 5.

Write notes on (a) Viterbi algorithm and its applications. (b) BCH codes and procedure for decoding of BCH codes.

6.

Given following ensembles S={S ,S , S , S , S , S , S } 1 2 3 4 5

6

7

P(S)={1/3,1/3,1/9,1/9,1/27,1/27,1/27} (a) Find H(S) & H (S3 ). (b) Find a compact Huffman code when X= [1,1] & X[0,1,2]. Find the average length and efficiency for both above codes.

7.

Explain the following in detail. (a) Source coding theorem. (b) Coding for discreteless sources. (c) Fixed length and variable length coding.

8.

(a) (b)

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State and explain Shannon-Fano theorem. Explain about Lempel –Ziv codes.