Master of Science II (Electronic Science)
Examination: Oct/Nov 2016 Semester III (New CBCS)
SLR No. Day
Date Time Subject Name Paper
No. Seat No.
SLR SJ
354
Friday
18/11/2016
2:30 PM
to
05.00 PM
Digital Communication
C
X
Instructions: All questions carry equal marks.
Q.1 and Q.2 are compulsory.
Attempt any THREE questions from Q.3 to Q.7
Use of non-programmable calculator is allowed.
Total Marks: 70
Q.1 Select the most correct alternative- 06
Non-uniform quantization leads to
Reduction in transmission bandwidth
Decrease in maximum SNR
Increase in SNR for low level signals
Simplification of quantization process
The practically used value of companding is
256 255
87.6 86.7
If dmin then it detects up to corrects up to
2 4
2 1
If bandwidth is 3000Hz and S/N 103, then capacity of channel is

30, 000bits/sec 30, 000bits/symbol
000bits/sec 000bits/symbol
Which one of the following is widely used modulation technique?
ASK FSK
PSK None of the above
The bit rate of ADM is
8 1
2
State whether following statements are true or false: 08
Shanon-heartly theorem indicates that a noiseless channel has an infinite
capacity.
The best time to sample the received waveform is when the eye opening is
largest.
The M-ary schemes conserve the channel bandwidth due to which it
requires more power.
A random process is said to be ergodic if time averages not equal to
ensemble averages.
Page 1 of 2
Coasts loop method is used for the symbol synchronization.
The (hamming) weight of a code vector is defined as the total number of
nonzero components of C.
The parity check matrix can be used to verify whether a codeword C is
generated by the matrix G.
The hardware implementation of FSK is more complex than PSK.
Q.2 Answer the following:
Write a short note on inter symbol interference. 05
Explain power spectral density of stationary random processes. 05
What is BCH code? 04
Q.3 What are the advantages of M-ary signaling scheme over binary? Explain
M-ary PSK system with the help of a neat block diagram of transmitter and
receiver.
10
A discrete source emits one of five symbols once every millisecond. The
symbol probabilities are 1/16 and 1/16 respectively. Find the
source entropy and information rate.
04
Q.4 A discrete memory less source emits following symbols with probability of
occurrence as shown below.
Symbol S0 S1 S2 S3 S4 S5 S6
Probabilit
y 0.25 0.25 0.125 0.125 0.125 0.0625 0.0625
Determine the Huffman code of each symbol and calculate code efficiency.
10
Write a short note on error correcting codes. 04
Q.5 The generator matrix for a block code is given below. Find all the code
vectors of this code.
08
What is the need of quantizer in digital communication? 06
Q.6 With the help of neat block diagrams, explain the working of transmitter and
receiver of a pulse code modulation.
08
Write a short note on eye diagram. 06
Q.7 Explain what do you mean by matched filter? Derive an expression for
impulse response of a matched filter.
08
Explain the early late bit synchronizer. 06