Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 2151004 Electronic And Communication Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code:2151004 Date:05/02/2021
Subject Name:Electronic and Communication
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1 (a) Define terms modulation and demodulation with respect to the
03
communication process.
(b) Differentiate passive and active components used to design
04
communication circuits. Also describe mutual inductance effect.
(c) With help of neat diagram describe the working principle of diode
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envelope detector circuit used for amplitude demodulation process.
Also determine the total power radiated by an antenna, given that
with modulation index 30% a transmitter supplies 8 KW carrier
signal power to it.
Q.2 (a) Comment on bandwidth requirement of a sinusoidal AM and FM
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wave during its propagation in channel medium.
(b) A sinusoidal carrier signal having amplitude 10 V and frequency
04
1000 KHz is amplitude modulated with sinusoidal information
signal having amplitude 5 V and frequency 100 KHz. Calculate (1)
power in side bands (2) total power in AM wave.(Assume R=1 ohm)
(c) Explain the trapezoidal method for monitoring the A.M waveform
07
using oscilloscope in detail. Also define term Skin effect.
Q.3 (a) Compare DSB-FC and SSB ?SC modulation schemes and prove that
03
use of SSB technology is preferable as compared to use of DSB
technology.
(b) Compare FM and AM methods. Also describe the Armstrong method
04
for generating FM waves with help of neat diagram.
(c) An FM wave is described as, e(t) = 10 sin (5 ? 108 t + 4 sin 1250 t)
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Determine the values of (i) The carrier frequency (ii) Modulating
frequency (iii) The modulation index and (iv) Carrier frequency
deviation for the same.
Q.4 (a) Describe the significance of synchronous product detector in SSB
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demodulation process.
(b) Explain the basic working principle of FM detector. Also describe
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working of foster seeley discriminator circuit with neat diagram.
(c) Enlist all SSB modulation schemes. Explain the Phasing method for
07
the same.
Q.5 (a) List out basic functions of communication receiver circuit.
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(b) Define term tracking with respect to a superhetrodyne receiver. Also
04
explain the three points tracking process used in radio receiver.
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(c) Describe briefly shot noise, partition noise and flicker noise with all
07
details.
Q.6 (a) Describe the equations of resonance frequency, Q factor and the ? 3 dB
03
bandwidth of the series tuned circuits.
(b) Derive the general Friis's formula to define noise factor of cascaded
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amplifiers.
(c) With help of neat general diagram describe the working of a super
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heterodyne receiver.
Q.7 (a) Mention the significance of series tuned circuit in the communication
03
process.
(b) Describe briefly about the HAM radio
04
(c) State and prove properties of Fourier transform.
07
Q.8 (a) Mention the significance of parallel tuned circuit in the communication
03
process.
(b) Describe utilization of HAM radio in natural calamities.
04
(c) State the Parseval's theorem. Also define terms ESD and PSD.
07
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This post was last modified on 04 March 2021