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ENEX 351Bachelor in Electronics, Communication and Information Engineering · Semester 61 Paper Available

Communication Systems

Past examination question papers and complete curriculum syllabus for Communication Systems (ENEX 351), Bachelor in Electronics, Communication and Information Engineering Semester 6 under Institute of Engineering (IOE), Tribhuvan University.

Sem 6 Subjects (6)View Full Semester Overview →
ENCT 355ICT Project ManagementENCE 356Engineering EconomicsENEX 351Communication SystemsENEX 352Telecommunication and Computer NetworksENEX 353Minor ProjectENEX 385-399Elective II
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6th-sem_Communication Systems.pdf

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Most Frequently Asked Questions

Top recurring IOE board exam questions for Communication Systems with verified mark schemes, formula notation, and recurrence frequency.

Showing 40 of 40 top repeated questions
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Year-wise & Session-wise Exam Papers

Complete questions from each exam session (Regular & Back exams from 2082 to 2069) for Communication Systems. Click any session paper to expand.

Showing 98 questions across 9 exam session papers
Institute of Engineering • 2082 Chaitra Board Examination
Q1[5 Marks]Introduction
a) Sketch a proper generic block diagram of a voice communication system between an onboard pilot and an air traffic controller, and briefly explain the needs and functioning of each building block of that system. [5] b) Define any ten performance parameters/impairments of digital communication system.
Q2[6 Marks]Introduction
(a) Determine whether the signal is time invariant or not. [6] (b) Consider any two signals and convolve them graphically.
Q3[8 Marks]Amplitude Modulation
Derive the time domain and frequency domain expressions of DSB-FC wave of a double-tone (single message-two carriers) AM, and draw their line spectrums.
Q4[8 Marks]Multiplexing Techniques
Write short notes on: (Any Three) [3×5] a) T1 and E1 Hierarchy used in telephony b) FDM vs TDM c) Trellis diagram with example d) PSD of white noise e) Hilbert transform
Q5[6 Marks]Baseband Digital Data Transmission
By assuming suitable bit streams, demonstrate how HDB3 and B8ZS line encoders work.
Q6[9 Marks]Baseband Digital Data Transmission
Encode "$E = \int\limits_{-\infty}^{+\infty} |x(t)|^2 dt$" using weighted Huffman encoder and calculate entropy.
Q7[7 Marks]Error Detection and Correction Coding
Generate a hamming code for 10101100 using even parities, and demonstrate how it corrects a single bit error.
Q8[6 Marks]Noise in Communication Systems
Derive the expression for the impulse response of a matched filter for AWGN channel.
Q9[7 Marks]Amplitude Modulation
Explain the modulation scheme of MSK with appropriate example.
Q10[8 Marks]Amplitude Modulation
Write short notes on: Hilbert transform
Q11[8 Marks]Introduction
Define any ten performance parameters/impairments of digital communication system.
Q12[8 Marks]Multiplexing Techniques
Write short notes on: T1 and E1 Hierarchy used in telephony
Q13[8 Marks]Multiplexing Techniques
Write short notes on: FDM vs TDM

Curriculum Syllabus & Course Topics

Chapter-wise Units & Micro-Syllabus Topics (9 Units)

  1. 1. Introduction

    • 1.1Review of signals and systems
    • 1.2Block diagram of analog and digital communication systems
    • 1.3System needs and requirements
    • 1.4Noise, attenuation, and interference

  2. 2. Amplitude Modulation

    • 2.1Time domain expressions, frequency domain representation, modulation index, signal bandwidth of amplitude modulated signal
    • 2.2AM for single and double tone message, carrier and sideband components, power in carrier and sideband components, bandwidth and power efficiency, Hilbert transform
    • 2.3Double sideband AM (DSB-FC), generation (Square law), detection (Envelope and square law method)
    • 2.4Double sideband suppress carrier (DSB-SC), Generation (Linear modulator, balance modulator), Synchronous detection method
    • 2.5Overview of SSB, VSB, and ISB modulations
    • 2.6Phase locked loop (PLL), demodulation of AM using PLL
    • 2.7Super-heterodyne AM receiver

  3. 3. Angle Modulation

    • 3.1Basic definition, time domain expression for frequency modulation (FM) and phase modulation (PM)
    • 3.2Time domain expression for single tone, modulated FM signals, spectral representation
    • 3.3Bandwidth of FM, Carson’s rule, narrow and wideband FM
    • 3.4Generation of FM: Direct and indirect
    • 3.5Demodulation of FM signals: Non-synchronous (Limiter discriminator) and synchronous (PLL)
    • 3.6Stereo FM, spectral details, pre-emphasis and de-emphasis network
    • 3.7Super-heterodyne Radio receiver for FM

  4. 4. Pulse Modulation

    • 4.1Sampling theorem, ideal sampling, practical sampling, aliasing effect, aperture effect, signal reconstruction
    • 4.2Fundamentals of PAM, PWM, and PPM, time domain representation
    • 4.3Pulse coded modulation (PCM), quantization, quantization error, quantization noise
    • 4.4Signal to quantization noise ratio (SQNR) in uniform quantization, SQNR improvements, non-uniform quantization, companding techniques (A-law, µ-Law)
    • 4.5DPCM, DM: Encoder, decoder, advantage, disadvantage, noise in DM

  5. 5. Multiplexing Techniques

    • 5.1Multiplexing fundamentals: FDM, TDM, WDM and applications
    • 5.2T1 and E1 TDM PCM telephony hierarchy
    • 5.3Multiple access fundamentals: FDMA, TDMA, CDMA, SDMA

  6. 6. Baseband Digital Data Transmission

    • 6.1Information theory, measurement of information, entropy, symbol rates and data rates
    • 6.2Shannon Hartley channel capacity theorem, implication of theorem, and theoretical limits
    • 6.3Compression techniques: Shannon-Fano, Huffman codes
    • 6.4Line coding schemes: Unipolar, polar, bipolar
    • 6.5RZ, NRZ, AMI, Manchester, differential Manchester, B8ZS, HDB3 for digital data transmission
    • 6.6ISI, Nyquist criteria, pulse shaping for zero ISI

  7. 7. Digital Modulation Techniques

    • 7.1Binary digital modulation (ASK, FSK, PSK), generation, properties, constellation diagram and detections
    • 7.2QPSK generation, properties, constellation diagram, and detections
    • 7.3M-ARY modulation techniques, M-PSK versus M-QAM

  8. 8. Error Detection and Correction Coding

    • 8.1Hamming weight, hamming distance, code vectors, constraint length, code rate, syndromes
    • 8.2Error detection and correction
    • 8.2.1Error detection codes: Checksum, CRC
    • 8.2.2Error correction codes: Linear block codes, hamming codes
    • 8.3Cyclic codes (Generator polynomial, parity-check polynomial)

  9. 9. Noise in Communication Systems

    • 9.1Definition, white noise, AWGN channel, PSDF, and AC function of white noise
    • 9.2Ideal low-pass and RC filtering of white noise, noise equivalent bandwidth of a filter
    • 9.3Optimum detection of a pulse in additive white noise, the matched filter, realization of matched filters (Time correlators), the matched filter for a rectangular pulse
    • 9.4Overview of error probability function in digital communication (ASK, FSK, and PSK)

Examination Scheme & Marks Distribution

Evaluation Structure

  • Final Board Theory Exam: 60 Marks (Pass mark: 24)
  • Internal Assessment: 40 Marks (Pass mark: 16)
  • Practical / Lab Exam: 25 or 50 Marks (Continuous lab evaluation + viva, where applicable)

* This is the general current IOE 60/40 scheme; verify course-specific details in the syllabus above.

Exam Preparation Guidelines

  • Review the available past examination paper to understand question styling, typical derivation topics, and marks allocation.
  • Cross-reference key answers with official syllabus units, standard textbooks, and lecture notes.
  • Structure answers with labeled diagrams, concise bullet points, and highlight final answers in numerical solutions.
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Curriculum Syllabus & Marking Scheme