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1gh   Role Of Communications Systems
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1gh Role Of Communications 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
    • 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. Bulletin Boards
    • Information exchange and discussion areas
    • Set up by:
      • Academics
      • User groups
      • Also used for illicit activities such as terrorism and paedophilia
  • 7. 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
  • 8. 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
      • Messages can be prioritised
  • 9. Disadvantages of e-mail
    • Overload
    • Viruses
    • Easy to overlook
    • Misuse
  • 10. 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 ( Mo dulator/ Dem odulator) for analogue lines
      • Telephones designed for speech (analogue signal)
      • Modems at either end convert digital-analogue and then analogue-digital.
    modem modem digital digital analogue
  • 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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