B.TechSemester 42022-23Communication EngineeringKEC-401

Communication Engineering (KEC-401) - AKTU Question Paper 2022-23

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 2022-23. 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:2022-23

University:AKTU / UPTU

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Questions Asked in 2022-23

Communication Engineering (KEC-401) — complete question paper

Section AAttempt all questions in brief. 2 x 10 = 20

a
Explain need of modulation in communication
b
Write down time convolution property of Fourier transform
c
Define frequency modulation and draw its output wa veform
d
Find the bandwidth of a frequency modulated signal having frequency deviation 30kHz and maximum message frequency is 500Hz
e
Define term Figure of merit
f
Draw characteristic curve of Additive white Gaussi an noise (AWGN)
g
Write down difference between DPCM and PCM
h
Find the Nyquist rate and Nyquist interval for sig nal: (i). X(t) = 8 sin(70πt) + 9cos(75 πt) (ii). X(t) = 30sin(100πt) cos(200 πt) (i) Discuss the reason why non -coherent demodulation is not possible for BPSK . (j) Write different types of digital modulation techni ques

Section BAttempt any three of the following: 10x3=30

a
Determine the Fourier transform of rectangular puls e and draw its magnitude spectrum
b
Illustrate Narrow Band Frequency Modulation with mathematical expression
c
Define threshold effect in angle modulation. Illustrate the relation between the transfer function of Pre-emphasis and De- emphasis for frequency modulation
d
State and prove the sampling theorem and explain how you will recover the original signal from its samples
e
Construct and explain the block diagram of Transmitter and receiver for a QAM

Section CAttempt any one part of the following: 10x1=10

a
Draw and explain the modulator and demodulator of DSB-SC
b
Derivethe mathematical expression for SSB-SC Modulation
a
Illustrate Wide Band Frequency Modulation with its spectrum and mathematical expression
b
Define phase modulation. Demonstrate the fundamenta l of the generation of FM with the help of PM and similarly the generation of PM with the help of
a
Derive the expression for probability of Error for binary phase shift keying
b
Write down the difference between Probability Density function and Cumulative Distribution Function with their properties
a
Define delta modulation. If a baseband analog messa ge is converted into PCM with a maximum message frequency 40 Hz. If this sig nal is sampled and encoded by 8-bit encoder, then obtained the bandwidth of PCM
b
Draw and explain the block diagram of transmitter, channel, and receiver of PCM system
a
Write down the difference between BPSK and QPSK. Explain QPSK generation and detection with its signal constellation diagram
b
Draw the block diagram of Transmitter and Receiver of BFSK. Explain its working

Question text is extracted from the official AKTU question paper PDF above. Hindi translations are omitted — every question is printed in English in the original paper. Last verified: 2026-08-23.

Repeated Questions — KEC-401

Questions that appeared in more than one session, found by comparing 2 years of Communication Engineering papers (2021-22, 2022-23)

Define frequency modulation and draw its output wa veform