SUBJECT CODE : IT2302
ANNA UNIVERSITY QUESTION PAPER INFORMATION THEORY AND CODING
B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010
IT 2302 — INFORMATION THEORY AND CODING
Time : Three hours Maximum : 100 Marks
Answer ALL questions
PART A — (10 × 2 = 20 Marks)
1. Differentiate: Uncertainty, Information and Entropy.
2. Define channel capacity.
3. State the advantages of Lempel-Ziv algorithm over Huffman coding.
4. Why is LPC not suitable to encode music signals?
5. Distinguish between global color table and local color table in GIF.
6. State the various methods used for text compression.
7. What is Syndrome?
8. Why are cyclic codes extremely well suited for error detection?
9. What are conventional codes? How are they different from block codes?
10. State the principle of Turbo coding.
PART B — (5 × 16 = 80 Marks)
11. (a) (i) Explain briefly the source coding theorem. (6)
(ii) Given five symbols 4 3 2 1 0 and , , , S S S S S with their respective
probabilities. 0.4, 0.2, 0.2, 0.1 and 0.1. Use Huffman's encoding for
symbols and find the average code word length. Also prove that it
satisfies source coding theorem. (10)
(b) State and prove the properties of mutual information. (16)
12. (a) Explain the concepts of frequency masking and temporal masking. How
they are used in perceptual coding? (16)
(b) Explain in detail Adaptive Huffman coding with the help of an example.
13. (a) With a block diagram, explain the working of JPEG encoder and decoder.
(b) With a block diagram, explain the MPEG algorithm for video encoding.
14. (a) For a linear block code, prove with example that
(i) The syndrome depends only on error pattern and not on
transmitted code word. (8)
(ii) All error patterns that differ by a codeword have the same
(b) Determine the encoded message for the following 8-bit data codes using
the CRC generating polynomial . ) ( 0 3 4 x x x n p + + = (16)
132 132 132
15. (a) A rate 1/3 convolution encoder has generating vectors as ) 100 ( 1
= g ,
) 101 ( and ) 111 ( 3 2
= = g g .
(i) Sketch the encoder configuration. (5)
(ii) Draw the code tree, state diagram and trellis diagram. (5)
(iii) If the message sequence is 10110, determine the output sequence of
the encoder. (6)
(b) Explain in detail the Viterbi algorithm for decoding of convolutional
codes with a suitable example. (16)