dc

8) For the data word 1110 in a (7, 4) non-systematic cyclic code with the generator
polynomial 1+x+x 3 , the code polynomial is [ ]
a) 1+x+x 3 +x 5 b) 1+x 2 +x 3 +x 5 c) 1+x 2 +x 3 +x 4 d) 1+x 4 +x 5
9) A source X with entropy 2 bits/message is connected to the receiver Y through a noise free
channel. The conditional probability of the source is H(X/Y) and the joint entropy of
the source and the receiver H(X, Y). Then [ ]
a) H(X,Y)= 2 bits/message b) H(X/Y)= 2 bits/message
c) H(X, Y)= 0 bits/message d) H(X/Y)= 1 bit/message
Cont…..2
Code No: 07A5EC09 :2: Set No.1
10) Which of the following is a p(Y/X) matrix for a binary Erasure channel [ ]
a) 11ppqq−⎡⎤⎢⎥−⎣⎦ b) c) d) None
II Fill in the blanks:
11) The information rate of a source is also referred to as entropy measured in
______________
12) H(X,Y)=______________ or __________________
13) Capacity of a noise free channel is _________________
14) The Shannon’s limit is ______________
15) The channel capacity with infinite bandwidth is not because ____________
16) Assuming 26 characters are equally likely , the average of the information content of
English language in bits/character is________________
17) The distance between two vector c1 and c2 is defined as the no.of components in which
they are differ is called as____________________
18) The minimum distance of a linear block code is equal to____________________of any
non-zero code word in the code.
19) A linear block code with a minimum distance d min
can detect upto ___________________
20) For a Linear Block code Code rate =_________________
-oOo-
Code No: 07A5EC09 Set No. 2
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
III B.Tech. I Sem., II Mid-Term Examinations, November – 2010
DIGITAL COMMUNICATIONS
Objective Exam
Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 20.
I Choose the correct alternative:
1) For the data word 1110 in a (7, 4) non-systematic cyclic code with the generator
polynomial 1+x 2 +x 3 , the code polynomial is [ ]
a) 1+x+x 3 +x 5 b) 1+x 2 +x 3 +x 5 c) 1+x 2 +x 3 +x 4 d) 1+x+x 5
2) A source transmitting ‘m’ number of messages is connected to a noise free channel. The
capacity of the channel is [ ]
a) m bits/symbol b) m 2 bits/symbol c) logm bits/symbol d) 2m bits/symbol
3) Which of the following is a p(Y/X) matrix for a binary symmetric channel [ ]
a) b) c) d) None
4) Exchange between channel bandwidth and (S/N) ratio can be adjusted based on [ ]
a)shannons limit b)shannons source coding