Download GTU BE/B.Tech 2018 Winter 5th Sem Old 151004 Electronic Communication Question Paper

Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 5th Sem Old 151004 Electronic Communication Previous Question Paper

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1
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER ?V (OLD) EXAMINATION ? WINTER 2018
Subject Code:151004 Date: 11/12/2018

Subject Name: Electronic Communication

Time: 10:30 AM TO 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) What is noise? Explain thermal noise. 07
(b) Explain Communication system with the help of block diagram 07

Q.2 (a) What is modulation? Explain the need of modulation. 07
(b) Two resistors of 20 K and 50 K are at room temperature of 15 degree
Celsius. for a given bandwidth of 10MHz, determine the thermal noise
voltage generated by
a) two resistors in series
b) two resistors in parallel
07
OR

(b)
A mixer circuit has a noise figure of 12 dB. It is preceded by an
amplifier that has an equivalent noise temperature of 200K and a power
gain of 30 dB. Calculate the equivalent noise temperature of
combination referred to amplifier input.
07

Q.3 (a) Explain the Superhetrodyne receiver with block diagram. 07
(b) Explain envelop detector for AM demodulation. 07
OR
Q.3 (a) What is AGC? Explain simple AGC and delayed AGC with proper
graph.
07
(b) Explain Adjacent channel selectivity and image frequency rejection. 07

Q.4 (a) Compare AM, FM and PM 07

(b)
List all the properties of Fourier transform. State and prove time Shifting
property.
07
OR

Q.4 (a) Find the Fourier transform of the signal:

07

Q.4 (b) Define Amplitude Modulation. Derive the expression for AM modulated
wave.
07

Q.5 (a) Give difference between SSB and VSB. Explain filter method with
necessary block diagram.
07
(b) Explain parallel tuned circuit and derive equation for resonant frequency
and Q-factor.
07
OR

Q.5 (a) Explain Series tuned circuit and derive equation for resonant frequency
and Q-factor.
07
(b) Explain phase shift method of SSB generation with necessary block
diagram.
07

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