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Candidates Are Required To Give Their Answers in Their Own Words As Far As Practicable. The Figures in The Margin Indicate Full Marks

This document is an exam for an Analog Communication course, consisting of 7 questions testing various topics: 1. Functional blocks of communication systems, channel bandwidth, and modulation. 2. Hilbert transforms, AM wave power savings at different modulation depths, and band-pass systems. 3. DSB-SC AM signals and sidebands, SSB-SC wave generation methods, and envelope detectors. 4. PLL carrier synchronization, coherent SSB-SC demodulation, and its applicability to DSB-SC. 5. Fourier series of FM waves, modulation indices of PM and FM with given deviation constants and signals. 6. Broadcasting types and CCITT standard group/super

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Manish Shrestha
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43 views2 pages

Candidates Are Required To Give Their Answers in Their Own Words As Far As Practicable. The Figures in The Margin Indicate Full Marks

This document is an exam for an Analog Communication course, consisting of 7 questions testing various topics: 1. Functional blocks of communication systems, channel bandwidth, and modulation. 2. Hilbert transforms, AM wave power savings at different modulation depths, and band-pass systems. 3. DSB-SC AM signals and sidebands, SSB-SC wave generation methods, and envelope detectors. 4. PLL carrier synchronization, coherent SSB-SC demodulation, and its applicability to DSB-SC. 5. Fourier series of FM waves, modulation indices of PM and FM with given deviation constants and signals. 6. Broadcasting types and CCITT standard group/super

Uploaded by

Manish Shrestha
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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POKHARA UNIVERSITY

Level: Bachelor Semester – Fall Year : 2005


Programme: BE. Full Marks: 100
Course: Analog Communication Time : 3hrs.
Candidates are required to give their answers in their own words as far
as practicable.
The figures in the margin indicate full marks.
Attempt all the questions.

1. a) Draw the functional block diagram of a communication system and 7


explain each block briefly.
b) Explain the importance of channel bandwidth with the help of 4
Hartley-Shannon law.
c) What is modulation? Discuss about the necessity of modulation in 4
communication.
2. a) Define Hilbert transform. Determine the Hilbert transform of 2+4
x(t) = A cos (2f0t + ).
b) Calculate the percentage of power saved when the carrier is 3+3
suppressed in an AM wave modulated to a depth of
i) 80% and ii) 60%
c) Define band pass systems and band-limited signals. 3
3. a) Suppose that the modulation signal m(t) is a sinusoid of the form 4
m(t) = a cos 2fm t fm << fc
Determine the DSB – SC AM signal and its upper and lower sidebands.
b) Explain the various methods used in the generation of a SSB – SC 7
wave.
c) Explain the principle of an envelope detector with a circuit diagram. 4
4. a) Describe in detail, how PLL can be used in carrier synchronization in 7
AM systems.
b) Explain the coherent detection method of demodulation of SSB – SC 8
wave. Can we use this method to demodulate DSB – SC AM signals?
Explain.
5. a) Derive the Fourier series representation of single – tone FM wave. 7
6
b) The carrier c(t) = Acos210 t in angle modulated (PM or FM) by the 4+4
sinusoidal signal m(t) = 2cos2000t. The deviation constants are kp =
1.5 rad/v and kf = 300 Hz/V.
Determine
i) modulation indices of PM and FM systems.
ii) the bandwidth in each case using Carson’s rule.
6. a) What is broadcasting? What are its types? Explain each of them 2+2+4
briefly.
b) How CCITT standard Groups, Supergroups and Mastergroups are 7
formed using SSB – SC in telephone? Explain.
7. Write short notes on (Any Two) 25

a) Balanced modulators
b) Distortion less transmission line
c) Multiplexing
d) Generation of FM using Armstrong’s method.

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