SKR Engineering College 2007 B.E Information Technology IF356 – INFORMATION CODING TECHNIQUES - Question Paper

SKR ENGINEERING COLLEGE
DEPARTMENT OF info TECHNOLOGY

IF356 – info CODING TECHNIQUES

MODEL examination

MAXIMUM MARKS: 100 TIME DURATION: three Hrs


ans all ques.

PART – A (10 X two = 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 obtain out the code for the provided data:
AAAABBCDAB
3. What kind of encoding technique is applied to AC and DC co-efficients in JPEG?
4. How to decode the provided 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 provided data compute the entropy by coding it using Shannon fano technique.
7. Compare Huffman coding and Shannon fano coding.
8. Give the different pulse modulation techniques pulse code modulation technique available. How do they differ from every other?
9. What is a Generator polynomial? provide a few standard generator polynomials.
10. Write any 2 features of discrete memory less channels.

PART – B (5 X 16 = 80 MARKS)

11.i) Discuss the different stages in JPEG standard (9)
ii) Differentiate loss less and lossy compression technique and provide 1 example for every. (4)
iii) State the prefix property of Huffman code. (3)

12.a)i) How will you compute channel capacity? (2)
ii) Write channel coding theorem and channel capacity theorem. (5)
iii) Calculate the entropy for the provided sample data (3)
AAABBBCCD
iv) Prove Shannon info Capacity theorem. (6)

(OR)

12.b)i) Use differential entropy to compare the randomness of random variables. (4)
ii) A 4 symbol alphabet has subsequent probabilities
Pr(ao) = 1/2
Pr(ao) = 1/4
Pr(ao) = 1/8
Pr(ao) = 1/8
and an entropy of 1.75 bits. obtain a codebook for this 4 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 2 vectors C1 = (0010011) and C2 = (0001111) are codewords of C and compute the hamming distance ranging from 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 fault vector e. (4)
iii) Calculate the syndromes for all possible fault vectors e with Hamming weight < = one and list them in a table. How can this be used to accurate a single bit fault 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 obtain the parity check matrix? (4)
iii) Give the syndrome decoding algorithm. (4)
iv) Design a linear block code with dmin = three for a few 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 different Dolby audio coders. (6)
ii) Discuss about any 2 audio coding techniques used in MPEG. (6)
iii) Write down the principle behind video compression. (4)

-----

Earning:   Approval pending.