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RGPV Computer Science (Semester 4)
Analog & Digital Communication
December 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) For the base band signal m(t)=2cos1000t+cos2000t, sketch the spectrum of m(t).
2 M
1(b) What do you understand by causal and non-causal system?
2 M
1(c) Write the explain Parseval's theorem.
3 M
Solve any one question from Q.1(d) & Q.1(e)
1(d) Write the difference between frequency domain and time domain representation of signals. Use suitable examples.
7 M
1(e) What do you understand by impulse response of a system? Difference between cross-correlation and auto-correlation.
7 M

2(a) Why modulation is needed for the transmission of the signals?
2 M
2(b) What are the merits of frequency modulation?
2 M
2(c) Explain BNFM and WBFM in Brief.
3 M
Solve any one question from Q.2(d) & Q.2(e)
2(d) Compare the following amplitude modulation system DSB with carrier, DSB/SC, SSB/SC and VSB.
7 M
2(e) What is Phase modulation? How it is related to frequency modulation. Show that a vector can be used to generate a FM signal.
7 M

3(a) Write and explain sampling theorem.
2 M
3(b) What is multiplexing? Why it is needed?
2 M
3(c) Explain the terms quantization process, quantization error and noise figure.
3 M
Solve any one question from Q.3(d) & Q.3(e)
3(d) Differentiate between the delta modulation and adaptive delta modulation techniques. Explain the importance of companding.
7 M
3(e) Define and describe Pulse Position Modulation (PPM) and explain how PPM is derived from Pulse Width Modulation (PWM)
7 M

4(a) What do you understand by digital modulation techniques?
2 M
4(b) What are functions of a repeater in a PCM system?
2 M
4(c) Draw the following data formats for the bit stream 11001011 polar NRZ, polar RZ, unipolar R/Z, AMI, Manchester.
3 M
Solve any one question from Q.4(d) & Q.4(e)
4(d) What are advantages of DPSK? The bit stream if 11100110001 is to be transmitted phase sequence and find out the defected output.
7 M
4(e) Draw the block diagram of QPSK system with that of BPSK system.
7 M

5(a) Describe minimum Hamming distance in brief.
2 M
5(b) Write and explain Shannon theorem.
2 M
5(c) Does Shannon-Hartley theorem tells about trade off between signal to noise ratio and bandwidth?Explain.
3 M
Solve any one question from Q.5(d) & Q.5(e)
5(d) Write and explain Shannon-Fano coding method using suitable example.
7 M
5(e) Write short note on Linear block codes, cyclic codes.
7 M

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