(SEM VI) THEORY EXAMINATION 2018-19 DIGITAL COMMUNICATION

Digital Communication (REC602) – Section-Wise Description

SECTION A: Short Answer Concepts (2 Marks Each)

Section A focuses on basic theoretical understanding of digital communication fundamentals. Questions in this section test whether the student is familiar with core definitions, comparisons, and basic formulas.
 

Students are expected to briefly explain topics like PSK vs FSK, where conceptual clarity matters more than derivations. Definitions related to signal level, data level, mean, variance, and signal space check understanding of statistical and signal concepts used throughout the subject. Some questions also touch on error probability, error control methods, and spread spectrum applications, which link theory to real-world communication systems.
 

Answers should be precise, clear, and to the point, usually 3–4 lines, without derivations or diagrams. This section mainly checks conceptual readiness before moving to numerical and descriptive problems.
 

DIGITAL-COMMUNICATION-REC-602

SECTION B: Descriptive & Numerical Questions (7 Marks Each)
 

Section B is designed to test in-depth understanding, analytical thinking, and numerical ability. Students must attempt any three questions, allowing them to choose topics they are confident in.

This section includes block diagram explanations, such as the digital communication system, where students explain transmitter, channel, noise, and receiver along with bandwidth limitations. Modulation techniques like QPSK are tested with both theory and waveform sketches, ensuring students understand both concept and representation.
 

Questions on random processes, CDMA near-far problem, and multi-user detection (MUD) examine the student’s ability to relate theory to system-level challenges. Numerical problems on spread spectrum systems, involving processing gain and jamming margin, test formula application and calculation accuracy.
 

Answers here should be well-structured, supported by diagrams, equations, and explanations, showing step-by-step reasoning where required.
 

DIGITAL-COMMUNICATION-REC-602

SECTION C: Problem Solving & Probability (7 Marks)
 

Section C focuses on coding theory and probability applications. Students attempt one question, which typically involves either Huffman coding or probability problems.
 

In Huffman coding questions, students are expected to explain the steps of code construction, draw the Huffman tree, determine the binary codes, and calculate coding efficiency. This tests understanding of data compression and information theory.
 

Alternatively, probability questions (like dice problems) evaluate the student’s ability to apply basic probability rules, sample space analysis, and logical reasoning.
 

Neat presentation, correct steps, and final results are essential to score full marks in this section.