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Role of Communication Systems

Role of Communication Systems. Introduction. The information age Made possible by development of telecommunications Modern business dependent upon telecommunications Telephone Fax Various computer links Public lines Private cables Microwave Fibre-optic links Satellite.

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Role of Communication Systems

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  1. Role of Communication Systems

  2. Introduction • The information age • Made possible by development of telecommunications • Modern business dependent upon telecommunications • Telephone • Fax • Various computer links • Public lines • Private cables • Microwave • Fibre-optic links • Satellite

  3. Communication systems • The Internet • LAN (Local Area Network) • WAN (Wide Area Network) • The World Wide Web • On-line information services • Electronic bulletin boards • Intranets

  4. The Internet • Essentially an enormous WAN • LAN – Local Area Network • WAN – Wide Area Network – connects computers and networks over a large geographical area • Developed from ARPANet – US Department of Defense late 60s • Creators first to see computers as communication devices rather than just processing devices • No central governing body • No control of content • Continues to grow at phenomenal rate • http://www.netsizer.com/ • Millions of users at any one time

  5. The World Wide Web • A collection of pages stored on computers throughout the world joined by hypertext links. • A link may be text or graphics • When you click upon them you be taken automatically to a related web page • Access provided and facilitated by browsers such as Netscape or Internet Explorer • Creation attributed to Tim Berners-Lee in 1989 • http://www.wired.com/news/technology/0,1282,31830,00.html

  6. On-line Services • Information-based • News, share prices, weather and sport • Service-based • Banking • Shopping • Education • Entertainment • Databases

  7. Bulletin Boards • Information exchange and discussion areas • Set up by: • Academics • User groups • Also used for illicit activities such as terrorism and paedophilia

  8. Intranets • Essentially a private internet • Set up by companies or schools • Allow sharing of information • Documents • Databases • Applications • Microsoft Office software allows businesses to view documents as web pages

  9. Electronic mail (E-mail) • E-mail has many advantages over both ordinary mail and the telephone. For example: • A message can be sent from your desk to anywhere in the world at the price of a local call • The same message can be sent simultaneously to a group of people • The message will arrive in at most a few hours, and can be picked up the next time the recipient looks at their e-mail • It is easy to send a reply to an e-mail as soon as it is received or forward it to someone else • Long files including video, sound and graphics can be sent automatically when the cheap rate starts after 6pm • Graphics and text can be electronically transmitted and placed in a document by the recipient

  10. analogue digital digital Accessing the Internet Basic hardware requirements • Computer • Telephone line • Standard line is cheapest option – theoretically up to 56K bps (bits per second) • ISDN (Integrated Subscriber Digital line) 128K bps • ADSL (Asymmetric Digital Subscriber Line) 8M bps downstream, 640K bps upstream • Modem (Modulator/Demodulator) for analogue lines • Telephones designed for speech (analogue signal) • Modems at either end convert digital-analogue and then analogue-digital. modem modem

  11. Accessing the Internet Basic software requirements • Connection via an ISP (Internet Service Provider) • Software package: • Browser • Comms. Software (TCP/IP protocol) • E-mail • FTP client for downloads and uploads • Newsreader to allow access to Usenet groups

  12. Telephones • Mobile phones are just about normal for everyone now • 42% of UK households in 1999 • 65% of UK households by end of 2000 • Source: http://www.rcb.dk/uk/staff/chm/wap.htm • WAP services have not hit expected heights • One-offs such as Big Brother did dramatically increase usage

  13. Facsimile transmission (Fax) • Indispensable to even the smallest business • Greatly speeds up business transactions • Scans and digitises images (text or graphics) • Transmits them in analogue form over a telephone line to another fax machine, which then produces a copy of the image on a piece of paper

  14. Advantage of Fax • Send documents e.g. orders, newspaper cuttings, maps, instantly • Send overnight at cheap rate • Written evidence with signature • No need for recipient to be there, unlike phone • For example, can book a car / hotel in Uganda with ease and get immediate confirmation

  15. Disadvantage of Fax • Paper jam • Runs out of paper / ribbon (when you’re away) • Attracts junk faxes

  16. Voicemail • A sophisticated answering machine • Various services or departments available when you press a particular key • Messages can be directed to individuals who are absent • Messages can be cleared or forwarded

  17. Teleconferencing • Allows people in different locations to exchange ideas and information interactively • Most basic form • Telephone or e-mail • More advanced – videoconferencing • Video cameras • Microphones • Large monitors • Computers • Codec required to convert and compress analogue video images and sound waves into digital signals to transfer over digital telephone lines • High-bandwidth required (at least ISDN) • Bandwidth is a measure of how much data can be passed down a line

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