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Fundamentals of Data Communication Networks
book

Fundamentals of Data Communication Networks

by Oliver C. Ibe
November 2017
Beginner content levelBeginner
320 pages
8h 38m
English
Wiley
Content preview from Fundamentals of Data Communication Networks

Chapter 2Physical Layer

2.1 Introduction

In this chapter, we consider the basic functions performed by the physical layer. In particular, we consider the following:

  • Signal classification
  • Fourier analysis: Fourier series and Fourier transform
  • Modulation and demodulation
  • Sampling theorem
  • Analog-to-digital conversion
  • Channel sharing schemes
  • Modems
  • Guided and unguided transmission media
  • Channel impairments.

2.2 Classification of Signals

Message signals are classified as either analog (or continuous-time) or digital (or discrete-time). Analog (or continuous-time) signals, which include speech, audio, and video, have an infinite number of values. Digital signals are predominantly binary in nature and thus are represented by two values: 0 and 1. These two values are called binary digits, or bits.

Signals found in communication systems are complex waveforms. However, in many instances, these waveforms can be analyzed as one or more sine waves of the form:

2.1 equation

where A is the amplitude of the sinusoid, f the frequency in Hertz (Hz), and ϕ the phase in radians.

As mentioned in Chapter 1, a transmitter is required to convert signals into a form suitable for transmission over a channel. A key operation is to change the signal's frequency range to match the frequency range, or bandwidth (BW), offered by the channel. In some systems, the signal's frequency content (or frequency spectrum ...

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Publisher Resources

ISBN: 9781119436256Purchase book