## Wednesday, November 4, 2009

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) |

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