# Dr. A.P.J. Abdul Kalam University BE IV SEM (IT) Communication Systems [IT-227] June 2021 Question Paper

Dr. A.P.J. Abdul Kalam University

Bachelor of Engineering

Fourth Semester Examination, June-2021

Communication Systems [IT-227]

Branch - IT

Time: 3:00 Hrs Max Marks 70

Note : 1. Attempt any five questions out of eight.

2. Each question carries equal marks.

Q.1 (a) Comment on frequency deviation, deviation ratio and Carson’s rule.

(b) With the help of suitable diagrams explain direct and indirect methods of

FM generation.

Q.2 Draw a block diagram of communication system and explain it briefly.

Q.3 (a) What is Double Side Band Suppressed Carrier (DSB-SC) modulation?

Explain the basic principal of DSB-SC modulation with suitable sketch.

(b) When the modulation percentage is 75%, an AM transmitter radiates

10kW power? How much of this is carrier Power?

Q.4 Give the difference between Frequency Modulation (FM) and Phase

Modulation (PM).

Q.5 Write and explain time and frequency shifting properties of Fourier

transform.

(i) Sensitivity

(ii) Selectivity

(iii) Fidelity

(b) With a block diagram, explain the working of high power AM Transmitter.

Q.7 What is a Coaxial cable? Which is the most common cable used for video

signals?

Q.8 Draw and explain any four of the following signals:

(i) Sinusoidal (ii) Unit step

(iii) Ramp (iv) Signum

(v) Rectangular pulse (vi) Impulse (delta)

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