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) — complete question paper · 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. Hindi translations are omitted — every question is printed in English in the original paper. Last verified: 2026-08-23.

Repeated Questions — BEC401

Questions that appeared in more than one session, found by comparing 3 years of Communication Engineering papers (2023-24, 2024-25, 2025-26)

3x

State the need of modulati on in communication system

Appeared in: 2023-24 · 2024-25 · 2025-26

2x

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?

Appeared in: 2023-24 · 2025-26

2x

Determine the figure of merit for Double Side Band Suppressed Carrier (DSBSC) system

Appeared in: 2023-24 · 2025-26

2x

State various types of noise s that are encountered in a communication system

Appeared in: 2023-24 · 2025-26

Communication Engineering — Other Year Papers

AKTU Communication Engineering PYQs from other sessions