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ANNA UNIVERSITY :: CHENNAI – 600 025

MODEL QUESTION PAPER

V SEMESTER

B.TECH. INFORMATION TECHNOLOGY

IF356 – INFORMATION CODING TECHNIQUES

Time : 3 Hours Max. Marks : 100

Answer all Questions

PART – A (10 X 2 = 20 MARKS)

1. Calculate the bit rate for a 16 bit per sample stereophonic music whose sampling

rate is 44.1 KSPS.

2. Draw the Huffman code tree and find out the code for the given data:

AAAABBCDAB

3. What type of encoding technique is applied to AC and DC co-efficients in JPEG?

4. How to decode the given frame sequence using MPEG coding technique.

IPBBPBBI

5. Draw the block diagram of DPCM signal encoder.

6. Probability

0.25

0.20

0.15

0.15

0.10

0.05 For the above given data calculate the entropy by coding it using Shannon fano

technique.

7. Compare Huffman coding and Shannon fano coding.

8. Give the various pulse modulation techniques pulse code modulation technique

available. How do they differ from each other?

9. What is a Generator polynomial? Give some standard generator polynomials.

10. Write any two featur es of discrete memory less channels.

PART – B (5 X 16 = 80 MARKS)

11.i) Discuss the various stages in JPEG standard (9)

ii) Differentiate loss less and lossy compression technique and give one example for

each. (4)

iii) State the prefix property of Huffman code. (3)

12.a)i) How will you calculate channel capacity? (2)

ii) Write channel coding theorem and channel capacity theorem. (5)

iii) Calculate the entropy for the given sample data (3)

AAABBBCCD

iv) Prove Shannon Information Capacity theorem. (6)

(OR)

12.b)i) Use differential entropy to compare the randomness of random variables. (4)

ii) A four symbol alphabet has following probabilities

Pr(ao) = 1/2

Pr(ao) = 1/4

Pr(ao) = 1/8

Pr(ao) = 1/8

and an entropy of 1.75 bits. Find a codebook for this four letter alphabet that satisfies

source coding theorem. (4)

iii) Write the entropy for a binary symmetric source. (4)

iv) Write down the channel capacity for a binary channel. (4)

13.a)i) Compare and contrast DPCM and ADPCM (6)

ii) Define pitch, period and loudness (6)

iii) What is decibel? (2)

iv) What is the purpose of DFT? (2)

(OR)

13.b)i) Explain Delta Modulation with examples. (6)

ii) Explain sub-band adaptive differential pulse code modulation. (6)

iii) What will happen if speech is coded at low bit rates? (4)

14.a) Consider a hamming code C which is determined by the parity check matrix.

H =

i) Show that the two vectors C1 = (0010011) and C2 = (0001111) are codewords of C

and calculate the hamming distance between them. (4)

ii) Assume that a codeword C was transmitted and that a vector r = c + e is received.

Show that the syndrome s = r.HT only depends on error vector e. (4)

iii) Calculate the syndromes for all possible error vectors e with Hamming weight < =

1 and list them in a table. How can this be used to correct a single bit error in an

arbitrary position. (4)

iv) What is the length and the dimension K of the code. Why can the minimum

Hamming distance dmin not be larger than three? (4)

(OR)

14.b)i) Define linear block code. (2)

ii) How to find the parity check matrix? (4)

iii) Give the syndrome decoding algorithm. (4)

iv) Design a linear block code with dmin = 3 for some block length n = 2m-1. (6)

15.a)i) What are Macro blocks and GOB’s? (4)

ii) On what factors does the quantisation threshold depends in H.261 standards. (3)

iii) Discuss the MPEG compression techniques. (9)

(OR)

15.b)i) Discuss about the various Dolby audio coders. (6)

ii) Discuss about any two audio coding techniques used in MPEG. (6)

iii) Write down the principle behind video compression. (4)