Andhra University 2007 B.E Electronics

First ques. compulsory
ans any four from the remaining
All ques. carry equal marks
1)
a) describe joint entropy and conditional entropy
b)Define binary symmetric channel
c)what is meant by automatic repeat request?
d)list any 2 distance properties of convolution codes
e)Differentiate continuous and discrete channels
f)what is burst fault correction?
g)Explain the principle of parity check bit coding

2)
a)The voice frequency modulation signal of a PCM system is quantized in 16 leads with the subsequent probabilities
p1=p2=p3=p4=0.1
p5=p6=p7=p8=0.05
p9=p10p11=p12=0.075
p13=p14=p15=p16=0.025
compute entropy and info rate presume tm=3KHz
b)Find the transferred info for the channels shown in fig.below
(some dig is given)
p(X1)=0.2,p(X2)=0.5p(X3)=0.3

3)
a)define and derive shannon-Harley theorem
b)calculate the bandwidth of the picture(video) signal in a television . The subsequent are the available data:
i)No.of distinguishable brightnes leads=10
ii)no.of elements per picture frame=30,00,000
iii)picture frames transmitted per second=30
iv)S/N required=30dB

4)
a)give the desired properties of a code . Distinguish ranging from irreducible and separable codes.
b)what is coding efficiency?show that the coding efficiency is max.cohen P(0)=P(1)

5)
a)Design a block code is for a minimum diatance of 3 and a increase block size of 8 bits
b)Explain the principle of genetating of trelliscede

6)
a)the generator polynomial of a (7,4) cyclic code is g(x)=1+x+x3 .Find the 16 code words of this code
b) compare and contrast cyclic codes with convolutional codes

7)
a)Consider a data communication system with the subsequent characteristics : increase bit rate=1000bit/sec
word size=8bit:channel bit fault probability is 1/2 exp(-10,000/rc) where rc is the channel bit rate that can vary from 1000 to 3000 bit/sec .For this system:
compute the word fault probability for uncoded trion
b)compare source coding and channel codin

8)write short notes on the following:
a) predictive coding
b)compare fault values incoded and uncoded trion
c)Algebraic codes

Earning:   Approval pending.