Communication Engineering (BEC401) - AKTU Question Paper 2024-25
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 2024-25. Published by Dr. A.P.J. Abdul Kalam Technical University (AKTU/UPTU), Lucknow. Free PDF download — no login required.
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Questions Asked in 2024-25
Communication Engineering (BEC401) — complete question paper · 70 marks · 3 Hours
- aRepresent following time domain signals into frequency domain : (i) δ(t) (ii) Sin(at)
- bWhy we need modulation in Communication System?
- cState Carson's Rule for estima ting the bandwidth of an FM signal
- dWhat is Figure of Merit
- fExplain pulse amplitude modulation (PAM)
- gExplain QPSK in short
- aExplain Single Sideband Suppressed Carrier (SSB-SC) modulati on. How does it differ from standard Amplitude Modulation (AM)? Derive the mathematica l expression for an SSB-SC signal. Discuss its advantages in terms of power and bandwidth
- bA message signal is given by: m(t)=5cos(1000πt).The carrier signal is given by c(t)=10cos(2π⋅105t). Given:For FM: k f=75 kHz/V and For PM: k p=1 rad/V. Write down expression of FM and PM signal. Compare bandwidth of both
- cExplain following : (i) Random Processes (ii) Autocorrelation Function (iii) Power Spectral Density for White Gaussian noise (iv) Probability Density Function (v) Cumulative Distribution Function
- dExplain the sampling theorem and its significance in the con text of pulse modulation. What happens if the sampling rate is below the Nyquist rate?
- eDiscuss QAM in detail
- aAn audio signal given by m(t) amplitude modulates a carrier signal c(t).Where m(t)= 40 sin(600πt) millivolt and c(t)=100 sin(2π×10 5.t) millivolt. (Load Resistance is of 1ohm). Calculate following: (i) Modulation Index (ii) Equation of AM Signal (iii) Message Signal Power (iv) Carrier Signal Power (v) Total AM Signal Power (vi) Bandwidth of AM Signal (vii) Transmission Efficiency
- bExplain working of DSB-SC Modulator and Demodulator
- aWrite down difference between N BFM and WBFM in terms of spectral characteristics and mathematical expression
- bDefine angle modulation. Compare frequency modulation (FM) a nd phase modulation (PM) in terms of signal representation, FOM, and practical implementation
- aDescribe how noise affects Amplitude Modulation (AM) systems . Derive an expression for the signal-to-noise ratio (SNR) in a coherent AM receiver
- bExplain the concepts of pre-emphasis and de-emphasis in FM s ystems. Derive how these techniques improve the SNR for high-frequency components of the modulating signal
- aDraw and explain block diagram of PCM. Also explain SNR in P CM
- bDefine Delta Modulation and Time Division Multiplexing
- aExplain Phase Shift Keying and Frequency shift keying with h elp of waveform. Explain working of both
- bExplain Minimum Shift Keying (MSK) in detail
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)
Why we need modulation in Communication System?
Appeared in: 2023-24 · 2024-25 · 2025-26
State Carson's Rule for estima ting the bandwidth of an FM signal
Appeared in: 2024-25 · 2025-26
Communication Engineering — Other Year Papers
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