B.TechSemester 42021-22Communication EngineeringKEC401

Communication Engineering (KEC401) - AKTU Question Paper 2021-22

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 2021-22. 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:2021-22

University:AKTU / UPTU

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Questions Asked in 2021-22

Communication Engineering (KEC401) — complete question paper

Section AAttempt all q u e s t i o n s i n b r i e f . 2*10 = 20

a
Define the bandwidth of a system and compare the bandwidth of DSB- C, DSB-SC and SSB-SC
b
Illustrate transmission eff iciency of DSB-C, DSB-SC, and SSB-SC. 1
c
Define Phase modulation a nd draw its output waveform. 2
d
Illustrate the concept of Car son’s rule for BW calculation. 2
e
Define Noise Factor for a system. 3
f
Interpret the noise perform ance of an amplitude modulated w ave in terms of noise figure
g
Elaborate the term TDM with example. 4
h
Find Nyquist rate & Interval f or signal: x(t) = 4sin(30πt) +3cos(70πt). 4 (i) Discuss the reason why non-c oherent demodulation is not possible for BPSK. (j) Explain and draw the signa l space diagram for FSK. 5

Section BAttempt any three o f t h e f o l l o w i n g : 10*3 = 30

a
Illustrate the idea of havi ng modulation index for an AM si gnal equal to 1, greater than 1, and less than 1
b
Demonstrate Frequency Modulat ion technique with its expression and output
c
Explain the properties of Probability Density function and Cumulative Distribution Function
d
Explain the following in refe rence to the delta modulation (DM)
a
Granular Noise and b. Slope overload Provide the quantization noise for the DM with a step size Δ (Delta)
e
Illustrate the Modulator and Demodulator for Amplitude Shif t Keying. 5

Section CAttempt any one p a r t o f t h e f o l l o w i n g : 10*1 = 10

a
Draw and explain the modulat or and demodulator of DSB-SC. 1
b
Find out the Continuous time Fourier transform of rectangul ar pulse. Also draw the magnitude spectrum of the output
a
Demonstrate Phase Modulati on with mathematical expression a nd its output
b
Derive and explain Narrow Ba nd Frequency Modulation with FM generator
a
Illustrate the Noise factor for coherent demodulation of a DSB-SC signaling
b
Illustrate the relation betw een the transfer function of Pr e-emphasis and De-emphasis for frequency modulation
a
Evaluate the sampling theorem for a low pass analog message signal with an explanation of the mathematical expression for the sampling process
b
Draw and explain the block diag ram of transmitter, channel and receiver of PCM system
a
Illustrate the concept of QPSK with its modulator and demod ulator. Also draw the signal space diagram for the QPSK
b
Illustrate the concept of MSK with its modulator and demodu lator. Also draw the signal space diagram for the MSK

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 — KEC401

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

Define Phase modulation a nd draw its output waveform. 2