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NTC / Engineering Service — Technical Subject (Paper II) Past Questions

Transcribed from the -c (technical subject) papers in pdf/ntcprep/.

Note: The three NTC PDFs are Instagram screenshots (source: @ntengineer) and some only captured part of the paper (Sections cut off). Only sections visible in the scan are reproduced. engsewa-8283-c was extracted from a text-layer PDF (full paper).

NTC 2079/03/09 — Telecom Engineer (Electronics & Communication)

Paper II · Technical Subject · Full Marks: 100 · Time: 3 hrs (Screenshot captured Section B and Section C only.)

Section B — 35 Marks

  1. Explain the V-I characteristics of MOSFET. [5]
  2. Draw generic block diagram of PCM transmitter and receiver. Explain each of the components in brief. [5+5=10]
  3. Distinguish between Fourier transform, Laplace transform and z-transform. Find the Fourier transform of impulse function. List the properties of convolution. [4+4+2=10]
  4. Mention types of antenna used in VHF band. How can you increase the gain of such antenna? Is it feasible to use parabolic antenna in VHF band? [2+6+2=10]

Section C — 35 Marks

  1. What is system bus? Explain different types of system bus in brief. [1+4=5]
  2. What are advantages and disadvantages of SMPS over linear power supply? Draw a full-wave rectifier circuit and explain its operation. How do you make the equipment safe from electrical hazards? Explain. [10]
  3. What are the advantages of the Open System Interconnection (OSI) Model in computer networks? Describe OSI layers with examples. What are the differences between OSI and TCP/IP model? [10]
  4. What do you mean by satellite communication? State Kepler's laws of orbital motion. Which kind of loss is the most important while transmitting signals through the earth's atmosphere (above 10 GHz)? Justify your answer. [2+3+5=10]

NTC 2081/05/07 — Telecom Engineer (Electronics & Communication)

Paper II · Technical Subject · Full Marks: 100 · (Subjective: 70) · Time: 2 hrs 30 min

Section A — 35 Marks

  1. Describe the working principle of thyristor-controlled rectifiers with circuit diagram. [5]
  2. Differentiate between scalar and vector magnetic potential. Derive the expression for magnetic boundary conditions. [5+5=10]
  3. The open-loop transfer function of a control system is given by \(G(s)H(s) = \dfrac{K}{s(s+\sigma)(s^2+4s+13)}\). Sketch the root locus for \(0 \le K \le \infty\) and find the breakaway point as well as the angle of departure from the complex poles. [6+4=10]
  4. Describe the function of Phase-Locked Loop (PLL) in communication systems. Discuss the principles and applications of Frequency Shift Keying (FSK) modulation in digital communications. Explain the concept of Pulse Code Modulation (PCM) and its advantages in digital communications. [3+4+3=10]

Section B — 35 Marks

  1. What are the factors that affect the uplink and downlink design in a geostationary satellite system? Explain. [5]
  2. Explain the architecture and key components of the Next Generation Network (NGN). Discuss its advantages over traditional telecommunication networks and provide examples of services enabled by NGN. Describe the role of the physical layer in the OSI model and give examples of technologies or protocols that operate at this layer. [4+3+3=10]
  3. Discuss the principle of total internal reflection and how it enables signal transmission in optical fibers. What are the main differences between optical transmitters and optical receivers in fiber-optic communications? Explain the principles of satellite communication, including satellite stabilization, tracking and wave propagation. Discuss the role of earth stations in this context and how they interact with satellites. [3+2+2+3=10]
  4. Write down the importance of earthing and shielding in a communication network. Describe the devices/measures used in lightning protection for telecom equipment. [4+6=10]

NTC 2082/03/30 — Telecom Engineer (Electronics & Communication)

Paper II · Technical Subject · Full Marks: 100 · Time: 3 hrs (Answer each Section in a separate answer book.)

Section A — 50 Marks

  1. Draw the circuit diagram of a 2-bit counter and explain it. [5]
  2. Explain the sampling theorem and describe how A-law and μ-law companding improve signal quality in PCM. [5]
  3. How do you make a JK flip-flop from an SR flip-flop? Explain in detail. [10]
  4. Discuss the working principles and radiation characteristics of dipole antennas. Also, explain the concept of polarization and impedance matching in antenna systems. An electromagnetic wave with a frequency of 5 MHz is propagating through a copper conductor with conductivity σ = 5.8 × 10⁷ S/m and relative permeability μᵣ = 1. Calculate the skin depth δ of the wave in the copper. Explain the significance of skin depth in high-frequency communication systems. [2+3+2+3=10]
  5. Compare open-loop and closed-loop control systems with suitable examples. Derive the transfer function of a simple closed-loop system and explain how the location of poles and zeros affects the system's stability and transient response. [3+3+4=10]
  6. Describe how synchronization is achieved in a DS-CDMA system. Compare DS-SS with FH-SS in terms of performance and applications. Why is DS-CDMA important? Clarify. [4+4+2=10]

Section B — 50 Marks

  1. How do you protect telecom equipment from electrical shock hazards and lightning? Discuss. [5]
  2. Explain the role of cache memory in a microcomputer system. How does it improve performance compared to main memory? Illustrate with an example. [5]
  3. Discuss the role of IP-based convergence in Next Generation Network (NGN). How does NGN support the convergence of voice, video and data? Analyze the challenges of achieving interoperability among different vendors and technologies in NGN. [3+3+4=10]
  4. Explain the working principle of optical fiber communication based on total internal reflection and Snell's law. Discuss different types of optical fibers and their properties. [5+5=10]
  5. Explain single-phase and three-phase circuits with their benefits and applications. Write the formula for star-to-delta connection conversion and delta-to-star connection conversion. [6+4=10]
  6. Explain the concept of cloud computing. List its types and explain one real-life application for each. A microprocessor reads an 8-bit binary value from port A and writes the complement of that value to port B. Write an algorithm and a flowchart to represent this logic. [2+4+4=10]

Engineering Service (Eng. Sewa) 2082/83 — Technical Subject

Full Marks: 100 · Time: 3 hrs (Extracted from text-layer PDF; complete paper.)

Section A — 30 Marks

  1. Explain the basic characteristics of a rectifier circuit. Show their mathematical expressions as applicable. [5]
  2. Explain the working principle of a full-wave bridge rectifier circuit with the help of the necessary circuit diagram. [5]
  3. Explain the principle of operation of Analog-to-Digital converters. With neat diagrams, describe the working of a successive-approximation Analog-to-Digital converter. [3+7=10]
  4. Describe the construction and working principle of a DC generator with a neat diagram. Also derive the emf equation of a DC generator. [7+3=10]

Section B — 30 Marks

  1. Differentiate between e-health and Tele-medicine. [5]
  2. Explain the difference between travelling waves and standing waves. With the help of neat diagrams, describe the formation of a standing wave on a string fixed at both ends and define nodes and antinodes. [2+3=5]
  3. Classify the different types of surface-detection techniques in computer graphics. Explain the back-face detection method for visible-surface detection. [5+5=10]
  4. Explain the concepts of baseband and passband transmission. Discuss the generation and constellation diagram of binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK). [4+6=10]

Section C — 20 Marks

  1. Derive radar range equations for air traffic control and weather radars. Mention similarities and differences between MLS and ILS. [8+2=10]
  2. Describe how the Frequency Monitoring System (FMS) detects, records and analyzes radio-frequency signals. Discuss the importance of signal classification, direction finding and homing procedures in effective frequency monitoring. [5+5=10]

Section D — 20 Marks

  1. Differentiate between vision, mission, goal and objective with suitable examples. Discuss the techniques used by a project manager for the management of conflict in an organization. [6+4=10]
  2. Explain the major importance of ITU services worldwide. Define the national frequency allocation plan in accordance with ITU. [6+4=10]

Quick observation

The NTC 2081 root-locus question asks for a breakaway point but prints the unresolved parameter \(\sigma\), not a numerical value, so it supports only a symbolic result unless an additional source value is found. Papers 2082 and Eng. Sewa contain short calculate sub-parts (skin depth and converter examples) embedded inside otherwise theory-heavy questions. The exam is overwhelmingly explain / describe / differentiate / derive / diagram.