Download GTU BE/B.Tech 2019 Winter 5th Sem New 2151004 Electronic And Communication Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- V (New) EXAMINATION - WINTER 2019

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Subject Code: 2151004 Date: 06/12/2019
Subject Name: Electronic and Communication
Time: 10:30 AM TO 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1 (a) Explain the skin effect in brief. 03
(b) Draw basic diagram of communication system and explain in brief. 04
(c) What is modulation? Why modulation required? Describe in detail. 07

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Q.2 (a) Define the following term 03
(1) Signal Bandwidth (ii) Power spectral density (iii) Distortion
(b) A series tuned circuit has a Q of 130 and a tuning capacitance of 250pF 04
and is resonant at 450 kHz. Determine (i) the impedance at resonance, and (ii) the relative response of circuit at a frequency of 400 kHz.
(c) Draw and explain circuit of envelope detector for AM 07

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OR

(c) Explain Double-sideband suppressed carrier (DSBSC) modulation with 07
mathematical analysis.

Q.3 (a) State and prove time shifting property of Fourier transform 03
(b) Determine the power content of the carrier and each of the sidebands 04

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for and AM signal having a percentage modulation of 80 % and total power of 2500 W
(c) Explain Carson’s rule in FM? Explain- Armstrong method of FM 07
generation.

OR

Q.3 (a) Describe briefly shot noise, partition noise and flicker noise. Why they 03

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are generated?
(b) Explain the importance of pre-emphasis and de-emphasis circuits. 04
(c) List all the basic FM demodulators. Draw and explain Foster Seeley 07
Discriminator in detail

Q.4 (a) Give comparison between AM and FM systems. 03

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(b) Explain the thermal noise in brief. 04
(c) Define noise factor and noise temperature. Derive the Friss’s formulac 07
for noise factor when amplifiers are in cascade connection.

OR

Q.4 (a) With related to Amplitude modulation discuss following 03

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parameters: (I) Bandwidth requirement (II) Power distribution in sidebands and carrier.
(b) Explain the delayed AGC with diagram. 04
(c) A FM voltage is represented by v=12sin(6 x 10% + 5cos 1250t) .Find 07
Carrier Frequency, Modulating Frequency, Modulation Index, Maximum Deviation

Q.5 (a) List main function of radio receiver. 03

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(b) Define the following terms related to radio receiver : 04
selectivity

Q5 (a) Explain Super-heterodyne principal and super-heterodyne 07
receiver.
(b) Explain what double spotting is and how it arises. 03

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(c) Determine Fourier transform of Signum function sgn(t) 04

Q5 (a) What is Ham radio? Discuss the importance of Ham radio during 07
natural calamines.

OR

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