Information Technology INT1001 Lecture 7 Wired & Wireless Communication 1

Information Technology INT1001

Lecture 7Wired & Wireless Communication

1

Computers Are Your Future

Tenth Edition

Chapter 3: Wired & Wireless Communication

Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall 2

Wired & Wireless Communication

3Copyright © 2009 Pearson Education, Inc. Publishing as Prentice Hall

Moving Data: Bandwidth and Modems

Communications is the method of sending and receiving messages electronically between two points.

Communication channels are the paths through which messages are passed from one location to another.

Communication occurs over communication channels.



Data movement over communication channels is performed through analog and digital signals. Analog signals obtain and translate

data into continuous waveforms. Digital signals change data into

discrete, discontinuous pulses.


Moving Data:Bandwidth and Modems



The maximum amount of data transmitted through a communication channel is referred to as bandwidth.

Broadband is any transmission medium transporting large amounts of data at high speeds.



Communication devices that enable data transmission over telephone lines are known as modems.



Modulation is the transformation of digital signals into analog signals.

Demodulation is the transformation of analog signals into digital signals.

The data transfer rate, the rate at which two modems exchange data, is measured in bits per second (bps).


Wired and Wireless Transmission Media

Wired transmission media use solid forms, such as twisted-pair, coaxial, and fiber-optic cables, to transmit data.

Wireless transmission media send data through the air or space by means of infrared, radio, or microwave signals.




Twisted-pair cables transmit data using four insulated twisted wires that shield against electromagnetic interference.

Coaxial cables transmit data and consist of a center copper wire surrounded by a layer of braided wire.


Fiber-optic cable is made up of thin strands of glass or plastic that carry data through pulses of light.

The infrared wireless transmission medium carries data through the air using light beams.



Radio transmissions enable data in such forms as music, photos, and voice conversations to travel through the air as radio frequency or radio waves.

Bluetooth is a short-range radio transmission technology that enables devices within 30 feet of each other to communicate wirelessly.



Microwaves transmit data and are high-frequency electro-magnetic radio waves with very short frequencies.

Satellites are microwave relay stations in space that transmit data through microwave signals to and from Earth-based stations.



Direct Broadcast Satellite (DBS) is a consumer satellite technology that receives digital TV signals through the use of a reception dish.

Computer systems using wireless transmission media require devices for communication called network access points.


Wired Communication via the Public Switched Telephone Network

The public switched telephone network (PSTN), a worldwide telephone system, is an immense network used for data and voice communications.

A subscriber loop carrier (SLC) is a curbside installation that connects subscribers.

A local loop is the area served by an SLC.





Multiplexing is a technique that enables sending more than one call over an individual line.

Last-mile technologies provide solutions for bottlenecks that result from the inability of users to access the PSTN’s high-speed fiber-optic cables.



Integrated Services Digital Networking (ISDN) is the standard that makes digital telephone and data service available. Connecting computers to ISDN lines

requires an ISDN adapter/digital modem.

With ISDN, there is no extended dial-in or connection delay.



Digital Subscriber Line (DSL) is the broad term for a group of technologies that offer high-speed access to the Internet.

A DSL modem is required to modulate and demodulate analog and digital signals.





A cable modem is a tool that gives a computer the ability to access the Internet through cable TV connections.

Leased lines enable continuous end-to-end communication between two points through specially conditioned telephone lines, such as T1 lines.



Last-mile technologies include: ISDN and DSL Cable modems and leased lines T3 lines Synchronous Optical Network

(SONET) Multichannel Multipoint Distribution

Service (MMDS)


Convergence: Is It a Phone or a Computer?

Digitization is the process of transforming data into a digital form.

Convergence means two things in IT: The blending of multiple industries

such as computers, consumer electronics, and telecommunications

The blending of products such as personal computers and telephones



Cellular telephones, originally analog devices, are digital devices that use radio signals to transmit voice, image, text, and video data.

Cells are the limited geographic areas through which signals are transmitted.



Each cellular network includes multiple mobile switching centers (MSCs) that control communication within a set of cells.



A Personal Communication Service (PCS) is a group of related digital cellular technologies that has rapidly replaced the majority of analog cellular services.

Digital cellular technologies use convergence to make smartphones, which combine the features of phones and computing devices.



Digital phones resolve some of the problems of analog telephones by: Reducing signal interference Increasing reception Enhancing protection from

eavesdropping Making it more difficult to commit cell

phone fraud



Web-enabled devices display and respond to markup languages, such as HTML or XML, that are used to build Web pages.

Examples include: PDAs Smartphones Notebooks


Wired and Wireless Applications

Internet telephony, aka VoIP (Voice over Internet Protocol), uses the Internet for real-time voice communication.

VoIP service providers offer computer-to-phone and phone-to-phone services for long-distance transmission through the Internet.




Videoconferencing transmits sound and video images to people in different locations through digital video technology.


Facsimile transmission (fax) makes it possible to transmit images of documents over telephone lines or the Internet.

A computerized version of a standalone fax machine is known as a fax modem, which enables a computer to perform as a fax machine.



Satellite technology is used for: Air navigation TV and radio broadcasting Paging Videoconferencing



Satellite radio is not affected by location, distance, or obstructions. Broadcasts of radio signals are sent

through satellites orbiting the Earth. Use of satellites permits usage in

areas with restricted local radio stations or bad AM/FM reception.



Global Positioning System (GPS) is a system of 27 satellites that interact to allow users to obtain driving directions and numerous other types of information.



Text messaging is comparable to receiving or transmitting small e-mail messages or instant messages through a cellular telephone.



Picture messaging is the transmission of color pictures and backgrounds. The cellular telephone acts as a camera.


What You’ve Learned

Bandwidth refers to the maximum data transfer capacity of a communication channel.

Modems are used to modulate and demodulate data sent over dial-up phone lines.

Communications involve both wired and wireless media.



Use of the public switched telephone network (PSTN), which is mostly digital, is decreasing because of the increase in the use of broadband alternatives.

Multiplexing is the sending of multiple telephone calls or messages on a single line.



Digitization is the conversion of voice, text, graphic, audio, and video data into a digital format. Convergence is the merging of products like phones and computers



Traditional wired technology can be used for VoIP and faxing, while wireless technology makes text and picture messages, satellite radios, and GPS services possible.


Documents

Information Technology INT1001 Lecture 7 Wired & Wireless Communication 1