Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-1 Introduction to Information Technology. Chapter 6: Telecommunications and Networks

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-2 The Telecommunications System  Components include: Hardware Media Networks Software Data comm providers Protocols Applications

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-3 Telecommunication Signals  Analog signals  Continuous waves  Information conveyed by changing wave characteristics (amplitude and frequency)  Digital signals  Discrete pulses  Information conveyed in binary form (on or off pulses)  Easily understood by computer

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-4 Wire-based Communication Channels  Twisted-pair wire (telephone wire)  Cheap and easy to work with  Slow; subject to interference; low security  Coaxial cable  Carries more data; shielded from interference  More expensive; harder to work with; low security

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-5 Wire-based Communication Channels (continued)  Fiber-optic cable  Transmit information as light waves through glass fiber  Fast; high-capacity; secure; not subject to interference

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-6 Wireless Communication Channels  Microwave  High capacity; inexpensive relative to wire  Requires line of sight transmission towers; subject to environmental interference  Satellite  Very high capacity; large coverage area  Expensive; propagation delay; requires encryption for security

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-7 Understanding Communication Media  Transmission speed  Bandwidth – the range of frequencies available in a channel  More bandwidth, more channel capacity  Transmission mode  Character by character (asynchronous)  Streams of characters (synchronous)  Transmission accuracy  Accuracy controls added to messages  Error detection and correction required

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-8 Telecomm Carriers and Services  Telecomm carriers – provide telecomm technology and services for data communication  Common carriers – long-distance phone companies  Value-added carriers – provide private telecomm systems and services for a fee

Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 6-9 Network Basics  Network – the communication devices, media, and software needed to connect two or more computer systems.  Local area networks– a network that spans a relatively small geographic distance  Wide area networks – network that spans a large geographic distance

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