dc

Cont…..2
Code No: 07A5EC09 :2: Set No.4
II Fill in the blanks:
11) PSK and FSK have a constant--------------
12) Granular noise occurs when step size is--------------
13) Converting discrete time continuous signal into discrete amplitude discrete time signal is
called-----------------.
14) The minimum symbol rate of a PCM system transmitting an analog signal band limited to
2 KHz, the number of Q-levels 64 is ------------------
15) In DM granular noise occurs if when step size is -------------
16) The combination of compressor and expander is called---------------------
17) Data word length in DM is ---------------
18) Band width of PCM signals is -----------
19) A signal extending over-4V to +4Vis quantized in to 8e maximum possible quantization
error obtainable is-------------
20) Probability of error of PSK scheme is-----------------------
-oOo-
Code No: 07A5EC09 Set No. 1
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
III B.Tech. I Sem., II Mid-Term Examinations, November – 2010
DIGITAL COMMUNICATIONS
Objective Exam
Name: ______________________________ Hall Ticket No.
Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 20.
I Choose the correct alternative:
1) The channel matrix of a noiseless channel [ ]
a)consists of a single nonzero number in each column.
b) consists of a single nonzero number in each row.
c) is an Identity Matrix. d) is a square matrix.
2 ) Information content of a message [ ]
a) increase with its certainty of occurrence. b) independent of the certainty of
occurrence.
c) increases with its uncertainty of occurrence. d) is the logarithm of its uncertainty of
occurrence.
3) The channel capacity of a BSC with the transition probability ½ is [ ]
a) 0 bits b) 1 bit c) 2 bits d) infinity
4) 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
5) 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
6) Which of the following is a p(Y/X) matrix for a binary symmetric channel [ ]
a) b) c) d) None
7) Exchange between channel bandwidth and (S/N) ratio can be adjusted based on [ ]
a)shannons limit b)shannons source coding
c) shannons channel coading d) Shannon Hartley theorem