Computers Are Your Future © 2005 Prentice-Hall, Inc.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 2 Computers Are Your Future Chapter 8 Wired and Wireless Communication

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 3 What You Will Learn About The limitations of the public switched telephone network (PSTN) for sending and receiving computer data Multiplexing and digital telephony Wireless transmission media How convergence is blurring the boundaries among popular communication devices Home networking using wired and wireless communications applications Teleconferencing and videoconferencing technology Telecommuting and workgroup computing

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 4 Connectivity is the ability to link various media and devices. Connectivity

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 5 Wired Communication via the PSTN The public switched telephone network (PSTN) is the world telephone system. It is used for data as well as voice communications. Twisted-pair wire and fiber-optic cable provide the connections for the system. Home and business phones are connected to subscriber loop carriers (SLCs). The area serviced by SLCs is called the local loop.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 6 Multiplexing Multiplexing technology enables simultaneous multi- use of transmission lines. Copper wire allows up to 24 simultaneous calls per wire. Fiber-optic cable permits up to 43,384 calls per strand.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 7 Last Mile Technologies The last mile refers to the phone lines that connect homes and businesses to the local loop. The inability of users to access the high-speed fiber-optic cable creates a bottleneck of data called the last mile problem. Digital telephony technologies that use twisted-pair wire are referred to as last mile technologies. ISDN DSL

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 8 Wireless Transmission Media Wireless transmission media refers to the methods of carrying data through the air or space using infrared, radio, or microwave signals. Infrared Microwave Radio

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 9 Infrared Infrared is a wireless transmission medium that carries data via light beams. Transmitter and receiver must be in line of sight. An IrDa port is needed to use infrared with a computer.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 10 Radio Radio is a wireless transmission medium that carries data via radio frequency signals. Wireless LANs in a home or business are one type of radio technology. Radio signals can be long range (between cities or regions) and short range (within a building). Radio signals are susceptible to noise and electrical interference.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 11 Microwaves Microwaves are high-frequency radio waves. Much of long-distance telephone service is carried by microwaves. Microwaves travel in a straight line. Microwave relay stations are built about 30 miles apart.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 12 Satellites Satellites are microwave relay stations suspended in space. They are positioned in geosynchronous orbits. Satellites use microwave signals to transmit data to and from earth-based microwave relay stations.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 13 Cellular Telephones Cellular telephones enable calls to be placed through a wireless telecommunications system. Cellular phones use radio or infrared signals. Cells are limited geographic transmission areas. A mobile telephone switching office (MTSO) monitors the signal strength of cellular phones.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 14 Personal Communication Service (PCS) Personal Communication Service (PCS) refers to digital cellular telephone service technologies. Digital cellular phones offer: Noise-free sound Improved coverage Protection from eavesdropping and phone fraud Voice recognition High-speed Internet access

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 15 Pagers Pagers work like a simple radio. Pagers are: Constantly listening for a specific signal from a transmitter Either one-way (only receive signals) or two-way (send and receive signals) Declining in use due to the increase in cell phone use

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 16 Web-Enabled Devices A web-enabled device is any device that can display and respond to HTML or XML. PDAs, cell phones, and tablet PCs are web-enabled devices.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 17 Facsimile (Fax) Transmission Fax transmission is the means of sending an image of a document over telephone lines. Fax modems support fax as well as data protocols.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 18 TV Internet Set-Tops Internet TV is an Internet service that uses a TV to: Broadcast TV programs Send and receive Access Web sites Navigate the Internet using a remote control

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 19 Wired and Wireless Home Networks Wired home networks use coaxial cable, telephone wires, cat-5 wires, or the homes electric power wiring. Wireless home networks use radio signals.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 20 Wired and Wireless Applications Teleconferencing: It is the simplest wired application for voice communication. A telephone is used to conduct a conference between more than two people who are separated by a distance. Videoconferencing: Two or more people can have a face-to-face meeting when they are geographically separated. Cameras, a computer, and videoconferencing software are used to conduct the conference.

Computers Are Your Future Chapter 8 © 2005 Prentice-Hall, IncSlide 21 Wired and Wireless Applications Telecommuting: Telecommuting is performing work at home while being linked to the office by telecommunications-equipped computers. The advantages of telecommuting include not having to commute, flexible hours, more family time, and familiar surroundings. Workgroup Computing: A workgroup is a group of individuals, working together on a task, who are able to communicate and collaborate by way of computers connected to a network. Groupware software is used by workgroups.