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MU Electrical Engineering (Semester 5)
Communication Engineering
May 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

1(a) State and prove sampling Theorem
5 M
1(b) Draw and explain the block diagram of a digital communication system.
5 M
1(c) Explain how FSK can be generated using ASK.
5 M
1(d) Explain the need for modulation in a communication system.
5 M

2(a) Generate Huffman's code for the five symbols of a source having probabilities: 0.5, 0.25, 0.125, 0.0625, and 0.0625. Find entropy of the source, average code word length and efficiency of the code.
10 M
2(b) Explain with neat block diagram the working of a super- heterodyne AM receiver.
10 M

3(a) Draw the spectrum of an AM waveform if the modulating signal is m(t)=(cos 2000πt+0.5cos 4000πt) and carrier is c(t) = 1.5 cos(1000πt). Calculate total power and power of sidebands.
10 M
3(b) What is a balanced modulator? With the help of waveforms, prove thet the carrier is getting suppressed.
10 M

4(a) A message 101101 is to be transmitted in cyclic code with a generator polynomial G(D)=D4+D3+1. Obtain the transmitted code word. How many check bits does the encoded message contain? Draw the encoding arrangement for the same.
10 M
4(b) Explain Delta modulation transmitter and receiver with the help of a neat block diagram. What is slope overload and hunting error?
10 M

5(a) Explain the functioning of Foster-Seeley discriminator with the help of neat circuit diagram and phasor diagram.
10 M
5(b) State and prove the properties of Fourier Transform.
10 M

Write short note on any three:
6(a) OFC
7 M
6(b) Quantization process.
7 M
6(c) Shannon-Hartley Theorem.
7 M
6(d) Pre-Emphasis and De-Emphasis.
7 M

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