B.TechSemester 42023-24Communication EngineeringBEC401

Communication Engineering (BEC401) - AKTU Question Paper 2023-24

B.Tech · Semester 4 · Free PDF Download

This is the official AKTU Communication Engineering Previous Year Question Paper for B.Tech Semester 4, academic session 2023-24. Published by Dr. A.P.J. Abdul Kalam Technical University (AKTU/UPTU), Lucknow. Free PDF download — no login required.

Course:B.Tech

Semester:Semester 4

Session:2023-24

University:AKTU / UPTU

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Questions Asked in 2023-24

Communication Engineering (BEC401) — extracted question text · 70 marks · 3 Hours

Section AAttempt all questions in brief. 2 x 7 = 14

a
State the need of modulati on in communication system
b
If modulation percentage of an a mplitude modulated system is 1 00 %, then determine its efficiency
c
What is the effect of modulati ng signal’s amplitude on bandwidth of FM system?
d
Define the term figure of merit
e
State two disadvantages of delta modulation
f
Find the Nyquist rate and N yquist interval for the signal x(t) = 20sin(100πt) cos(200πt)
g
State difference between convent ional phase shift keying and d ifferential phase shift keying

Section BAttempt any three of the following: 7 x 3 = 21

a
Draw the block diagram of a co mmunication system. The antenna current of an AM broadcast transmitter, modulated to a depth of 30 % by an audio sine wave is 10 A. It increases to 12 A as a result of sinusoidal modulation by another audio sine wave. What is the modulation index due to second wave?
b
With the help of block diagram, explain the demodulation of FM wave using Phase Locked Loop (PLL)
c
Determine the figure of merit for Double Side Band Suppressed Carrier (DSBSC) system
d
With help of a neat block diagr am, discuss transmitter and receiver of PCM system
e
Discuss Quadrature Amplitude Modulation (QAM) in detail

Section CAttempt any one part of the following: 7 x 1 = 7

a
An Audio frequenc y signal 40 Sin (6π × 500 t) is used to amplitude modulate a carrier of 200 Sin (6 π × 106 t). Calculate: (i)Amplitude of message signal (ii)Amplitude of each side band (iii)Total power delivered to the load of 5 KΩ (iv) Carrier Power (v) Transmission efficiency
b
With help of neat diagram, illustrate the working of ring m odulator as DSB-SC Modulator
a
Why Pre-emphasis and De-emphasis is done in frequency modul ation. Discuss in detail
b
With help of neat block diagram, discuss how FM wave is gen erated using AM wave and its vice-versa
a
With help of a block diagr am, discuss time division multiplexing
b
With help of neat diagram, e xplain the working of delta modulator
a
State various types of noise s that are encountered in a communication system
b
Prove that for a PCM signal, Signal to Quantization Noise R atio (SQNR) in dB is given as 1.8+6R, where R represents no. of bits per sample
a
With help of wave forms, explain amplitude shift keying. Al so draw the block diagram of its modulator and demodulator
b
Write a short note on Mi nimum Shift Keying (MSK)

Question text is extracted from the official AKTU question paper PDF above. Check the original PDF for equations, diagrams and complete wording. Extracted: 2026-08-23.

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