Anna University
Department of Information Technology
Department of Information Technology
Department :
B.Tech I.T
Semester : V
Year : 3rd yr
Year : 3rd yr
UNIT – I
1. (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 AAABBBCCD (3) (iv)Prove Shannon information
capacity theorem (6)
2. (i)Use
differential entropy to compare the randomness of random variables (4)
(ii)A four
symbol alphabet has following probabilities
Pr(a0) =1/2
Pr(a0) = 1/4
Pr(a0) = 1/8
Pr(a0) = 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)
3. A
discrete memory less source has an alphabet of five symbols whose probabilities
of occurrence are as described here
Symbols: X1
X2 X3 X4 X5
Probability:
0.2 0.2 0.1 0.1 0.4
Compare the
Huffman code for this source .Also calculates the efficiency of the source
encoder (8)
(b) A voice
grade channel of telephone network has a bandwidth of 3.4 kHz Calculate
(i) The
information capacity of the telephone channel for a signal to noise ratio of 30
dB and
(ii) The min
signal to noise ratio required to support information transmission through the
telephone channel at the rate of 9.6Kb/s (8)
4. A
discrete memory less source has an alphabet of seven symbols whose
probabilities of occurrence are as described below
Symbol: s0
s1 s2 s3 s4 s5 s6
Prob : 0.25
0.25 0.0625 0.0625 0.125 0.125 0.125
(i) Compute
the Huffman code for this source moving a combined symbols as high as possible
(10)
(ii)
Calculate the coding efficiency (4)
(iii) Why
the computed source has a efficiency of 100% (2)
5. (i)
Consider the following binary sequences 111010011000101110100.Use the Lempel –
Ziv algorithm to encode this sequence. Assume that the binary symbols 1 and 0
are already in the code book (12)
(ii)What are
the advantages of Lempel – Ziv encoding algorithm over Huffman coding? (4)
6. A
discrete memory less source has an alphabet of five symbols with their
probabilities for its output as given here
[X] = [x1 x2
x3 x4 x5 ]
P[X] = [0.45
0.15 0.15 0.10 0.15]
Compute two
different Huffman codes for this source .for these two codes .Find
(i) Average
code word length
(ii)
Variance of the average code word length over the ensemble of source symbols
(16)
7. A
discrete memory less source X has five symbols x1,x2,x3,x4 and x5 with
probabilities p(x1) – 0.4, p(x2) = 0.19, p(x3) = 0.16, p(x4) = 0.15 and p(x5) =
0.1 (i) Construct a Shannon – Fano code for X,and Calculate the efficiency of
the code (7)
(ii) Repeat
for the Huffman code and Compare the results (9)
8. Consider
that two sources S1 and S2 emit message x1, x2, x3 and y1, y2,y3 with joint
probability P(X,Y) as shown in the matrix form.
Calculate
the entropies H(X), H(Y), H(X/Y), and H (Y/X) (16)
9. Apply
Huffman coding procedure to following massage ensemble and determine Average
length of encoded message also. Determine the coding efficiency. Use coding
alphabet D=4.there are 10 symbols.
X = [x1, x2,
x3……x10]
P[X] =
[0.18,.0.17,0.16,0.15,0.1,0.08,0.05, 0.05,0.04,0.2] (16)
UNIT II
1.
(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)
2.
(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)
3. With the
block diagram explain DPCM system. Compare DPCM with PCM & DM systems (16)
4. (i).
Explain DM systems with block diagram (8)
(ii)
Consider a sine wave of frequency fm and amplitude Am, which is applied to a
delta modulator of step size Δ .Show that the slope overload distortion will
occur Information Coding Techniques
if Am > Δ
/ ( 2fmTs)
Where Ts
sampling. What is the maximum power that may be transmitted without slope
overload distortion? (8)
5. Explain
adaptive quantization and prediction with backward estimation in ADPCM system
with block diagram (16)
6. (i)
Explain delta modulation systems with block diagrams (8)
(ii) What is
slope – overload distortion and granular noise and how it is overcome in
adaptive delta modulation (8)
7. What is
modulation? Explain how the adaptive delta modulator works with different
algorithms? Compare delta modulation with adaptive delta modulation (16)
8. Explain
pulse code modulation and differential pulse code modulation (16)
UNIT III
1. Consider
a hamming code C which is determined by the parity check matrix
(i) Show
that the two vectors C1= (0010011) and C2 = (0001111) are code words of C and
Calculate the hamming distance between them (4)
(ii) Assume
that a code word C was transmitted and that a vector r = c + e is received.
Show that the syndrome S = r. H T 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)
(iii) What
is the length and the dimension K of the code? Why can the min Hamming distance
dmin not be larger than three? (4)
2. (i)
Define linear block codes (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)
3. a.
Consider the generator of a (7,4) cyclic code by generator polynomial g(x) –
1+x+x3.Calculate the code word for the message sequence 1001 and Construct
systematic generator matrix G. (8)
b. Draw the
diagram of encoder and syndrome calculator generated by polynomial g(x)? (8)
4. For the
convolution encoder shown below encode the message sequence (10011). also
prepare the code tree for this encoder (16)
5. (i)Find a
(7,4) cyclic code to encode the message sequence (10111) using generator matrix
g(x) = 1+x+x3 (8)
(ii)
Calculate the systematic generator matrix to the polynomial g(x) = 1+x+x3.Also
draw the encoder diagram (8)
6. Verify
whether g(x) = 1+x+x2+x3+x4 is a valid generator polynomial for generating a
cyclic code for message [111] (16)
7. A
convolution encoder is defined by the following generator polynomials:
g0(x) =
1+x+x2+x3+x4 g1(x) = 1+x+x3+x4 g2(x) = 1+x2+x4
(i) What is
the constraint length of this code? (4)
(ii) How
many states are in the trellis diagram of this code ( 8) (iii) What is the code
rate of this code? (4)
8. Construct
a convolution encoder for the following specifications: rate efficiency =1/2
Constraint
length =4.the connections from the shift to modulo 2 adders are described by
following equations
g1(x) = 1+x
g2(x) = x
Determine
the output codeword for the input message [1110] (16)
UNIT IV
1.
(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)
2. Write the
following symbols and probabilities of occurrence, encode the
Message
“went#” using arithmetic coding algorithms. Compare arithmetic coding
with Huffman
coding principles (16) Symbols: e n t w #
Prob : 0.3
0.3 0.2 0.1 0.1
3. (a)Draw
the JPEG encoder schematic and explain (10)
(b) Assuming
a quantization threshold value of 16, derive the resulting quantization error
for each of the following DCT coefficients 127, 72, 64, 56,-56,-64,-72,-128.
(6)
4.
(i)Explain arithmetic coding with suitable example (12)
(ii) Compare
arithmetic coding algorithm with Huffman coding (4).
5. (i)Draw
JPEG encoder block diagram and explain each block (14)
(ii) Why DC
and AC coefficients are encoded separately in JPEG (2)
6.
(a)Discuss in brief ,the principles of compression (12)
(b) in the
context of compression for Text ,Image ,audio and Video which of the
compression techniques discussed above are suitable and Why? (4)
7.
(i)Investigate on the „block preparation „and quantization phases of JPEG
compression process with diagrams wherever necessary (8)
(ii)
Elucidate on the GIFF and TIFF image compression formats (8)
UNIT V
1.
(i)Explain the principles of perceptual coding (14)
(ii) Why LPC
is not suitable to encode music signal? (2)
2.
(i)Explain the encoding procedure of I,P and B frames in video encoding with
suitable diagrams (14)
(ii) What
are the special features of MPEG -4 standards (2)
3. Explain
the Linear Predictive Coding (LPC) model of analysis and synthesis of speech
signal. State the advantages of coding speech signal at low bit rates (16)
4. Explain
the encoding procedure of I,P and B frames in video compression techniques,
State intended application of the following video coding standard MPEG -1 ,
MPEG -2, MPEG -3 , MPEG -4 (16)
5. (i)What
are macro blocks and GOBs? (4)
(ii) On what
factors does the quantization threshold depend in H.261 standards? (3)
(iii)Discuss
the MPEG compression techniques (9)
6.
(i)Discuss about the various Dolby audio coders (8)
(ii) Discuss
about any two audio coding techniques used in MPEG (8)
7. Discuss
in brief, the following audio coders: MPEG audio coders (8)
DOLPY audio
coders (8)
8.
(i)Explain the “Motion estimation” and “Motion Compensation” phases of P and B
frame encoding process with diagrams wherever necessary (12)
(ii) Write a
short note on the “Macro Block” format of H.261 compression standard (4)
