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Business Data Communications and Networking by Alan Dennis, Jerry FitzGerald

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Chapter 3. PHYSICAL LAYER

PHYSICAL LAYER

THE PHYSICAL layer (also called layer 1) is the physical connection between the computers and/or devices in the network. This chapter examines how the physical layer operates. It describes the most commonly used media for network circuits and explains the basic technical concepts of how data is actually transmitted through the media. Four different types of transmission are described: digital transmission of digital computer data; analog transmission of digital computer data; digital transmission of analog voice data; and combined analog-digital transmission of digital data. You do not need an engineering-level understanding of the topics to be an effective user and manager of data communication applications. It is important, however, that you understand the basic concepts, so this chapter is somewhat technical.

OBJECTIVES

  • Be familiar with the different types of network circuits and media

  • Understand digital transmission of digital data

  • Understand analog transmission of digital data

  • Understand digital transmission of analog data

  • Be familiar with analog and digital modems

  • Be familiar with multiplexing

CHAPTER OUTLINE

INTRODUCTION

CIRCUITS

  • Circuit Configuration

  • Data Flow

  • Multiplexing

  • How DSL Transmits Data

COMMUNICATION MEDIA

  • Guided Media

  • Wireless Media

  • Media Selection

DIGITAL TRANSMISSION OF DIGITAL DATA

  • Coding

  • Transmission Modes

  • Digital Transmission

  • How Ethernet Transmits Data ...

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