1gh Role Of Communications Systems


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1gh Role Of Communications Systems

  1. 1. Role of Communication Systems
  2. 2. Introduction <ul><li>The information age </li></ul><ul><ul><li>Made possible by development of telecommunications </li></ul></ul><ul><ul><li>Modern business dependent upon telecommunications </li></ul></ul><ul><ul><ul><li>Telephone </li></ul></ul></ul><ul><ul><ul><li>Fax </li></ul></ul></ul><ul><ul><ul><li>Various computer links </li></ul></ul></ul><ul><ul><ul><ul><li>Public lines </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Private cables </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Microwave </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fibre-optic links </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Satellite </li></ul></ul></ul></ul>
  3. 3. Communication systems <ul><li>The Internet </li></ul><ul><li>LAN (Local Area Network) </li></ul><ul><li>WAN (Wide Area Network) </li></ul><ul><li>The World Wide Web </li></ul><ul><li>Electronic bulletin boards </li></ul><ul><li>Intranets </li></ul>
  4. 4. The Internet <ul><li>Essentially an enormous WAN </li></ul><ul><ul><li>LAN – Local Area Network </li></ul></ul><ul><ul><li>WAN – Wide Area Network – connects computers and networks over a large geographical area </li></ul></ul><ul><li>Developed from ARPANet – US Department of Defense late 60s </li></ul><ul><ul><li>Creators first to see computers as communication devices rather than just processing devices </li></ul></ul><ul><li>No central governing body </li></ul><ul><li>No control of content </li></ul><ul><li>Continues to grow at phenomenal rate </li></ul><ul><ul><li>http://www.netsizer.com/ </li></ul></ul><ul><li>Millions of users at any one time </li></ul>
  5. 5. The World Wide Web <ul><li>A collection of pages stored on computers throughout the world joined by hypertext links. </li></ul><ul><ul><li>A link may be text or graphics </li></ul></ul><ul><ul><li>When you click upon them you be taken automatically to a related web page </li></ul></ul><ul><li>Access provided and facilitated by browsers such as Netscape or Internet Explorer </li></ul><ul><li>Creation attributed to Tim Berners-Lee in 1989 </li></ul><ul><ul><li>http://www.wired.com/news/technology/0,1282,31830,00.html </li></ul></ul>
  6. 6. Bulletin Boards <ul><li>Information exchange and discussion areas </li></ul><ul><li>Set up by: </li></ul><ul><ul><li>Academics </li></ul></ul><ul><ul><li>User groups </li></ul></ul><ul><ul><li>Also used for illicit activities such as terrorism and paedophilia </li></ul></ul>
  7. 7. Intranets <ul><li>Essentially a private internet </li></ul><ul><li>Set up by companies or schools </li></ul><ul><ul><li>Allow sharing of information </li></ul></ul><ul><ul><ul><li>Documents </li></ul></ul></ul><ul><ul><ul><li>Databases </li></ul></ul></ul><ul><ul><ul><li>Applications </li></ul></ul></ul><ul><li>Microsoft Office software allows businesses to view documents as web pages </li></ul>
  8. 8. Electronic mail (E-mail) <ul><li>E-mail has many advantages over both ordinary mail and the telephone. For example: </li></ul><ul><ul><li>A message can be sent from your desk to anywhere in the world at the price of a local call </li></ul></ul><ul><ul><li>The same message can be sent simultaneously to a group of people </li></ul></ul><ul><ul><li>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 </li></ul></ul><ul><ul><li>It is easy to send a reply to an e-mail as soon as it is received or forward it to someone else </li></ul></ul><ul><ul><li>Long files including video, sound and graphics can be sent automatically when the cheap rate starts after 6pm </li></ul></ul><ul><ul><li>Graphics and text can be electronically transmitted and placed in a document by the recipient </li></ul></ul><ul><ul><li>Messages can be prioritised </li></ul></ul>
  9. 9. Disadvantages of e-mail <ul><li>Overload </li></ul><ul><li>Viruses </li></ul><ul><li>Easy to overlook </li></ul><ul><li>Misuse </li></ul>
  10. 10. Accessing the Internet <ul><li>Basic hardware requirements </li></ul><ul><li>Computer </li></ul><ul><li>Telephone line </li></ul><ul><ul><li>Standard line is cheapest option – theoretically up to 56K bps (bits per second) </li></ul></ul><ul><ul><li>ISDN (Integrated Subscriber Digital line) 128K bps </li></ul></ul><ul><ul><li>ADSL (Asymmetric Digital Subscriber Line) 8M bps downstream, 640K bps upstream </li></ul></ul><ul><li>Modem ( Mo dulator/ Dem odulator) for analogue lines </li></ul><ul><ul><li>Telephones designed for speech (analogue signal) </li></ul></ul><ul><ul><li>Modems at either end convert digital-analogue and then analogue-digital. </li></ul></ul>modem modem digital digital analogue
  11. 11. Accessing the Internet <ul><li>Basic software requirements </li></ul><ul><li>Connection via an ISP (Internet Service Provider) </li></ul><ul><ul><li>Software package: </li></ul></ul><ul><ul><ul><li>Browser </li></ul></ul></ul><ul><ul><ul><li>Comms. Software (TCP/IP protocol) </li></ul></ul></ul><ul><ul><ul><li>E-mail </li></ul></ul></ul><ul><ul><ul><li>FTP client for downloads and uploads </li></ul></ul></ul><ul><ul><ul><li>Newsreader to allow access to Usenet groups </li></ul></ul></ul>
  12. 12. Telephones <ul><li>Mobile phones are just about normal for everyone now </li></ul><ul><ul><li>42% of UK households in 1999 </li></ul></ul><ul><ul><li>65% of UK households by end of 2000 </li></ul></ul><ul><ul><ul><li>Source: http://www.rcb.dk/uk/staff/chm/wap.htm </li></ul></ul></ul><ul><li>WAP services have not hit expected heights </li></ul><ul><ul><li>One-offs such as Big Brother did dramatically increase usage </li></ul></ul>
  13. 13. Facsimile transmission (Fax) <ul><li>Indispensable to even the smallest business </li></ul><ul><li>Greatly speeds up business transactions </li></ul><ul><li>Scans and digitises images (text or graphics) </li></ul><ul><li>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 </li></ul>
  14. 14. Advantage of Fax <ul><li>Send documents e.g. orders, newspaper cuttings, maps, instantly </li></ul><ul><li>Send overnight at cheap rate </li></ul><ul><li>Written evidence with signature </li></ul><ul><li>No need for recipient to be there, unlike phone </li></ul><ul><li>For example, can book a car / hotel in Uganda with ease and get immediate confirmation </li></ul>
  15. 15. Disadvantage of Fax <ul><li>Paper jam </li></ul><ul><li>Runs out of paper / ribbon (when you’re away) </li></ul><ul><li>Attracts junk faxes </li></ul>
  16. 16. Voicemail <ul><li>A sophisticated answering machine </li></ul><ul><ul><li>Various services or departments available when you press a particular key </li></ul></ul><ul><ul><li>Messages can be directed to individuals who are absent </li></ul></ul><ul><ul><li>Messages can be cleared or forwarded </li></ul></ul>
  17. 17. Teleconferencing <ul><li>Allows people in different locations to exchange ideas and information interactively </li></ul><ul><li>Most basic form </li></ul><ul><ul><li>Telephone or e-mail </li></ul></ul><ul><li>More advanced – videoconferencing </li></ul><ul><ul><li>Video cameras </li></ul></ul><ul><ul><li>Microphones </li></ul></ul><ul><ul><li>Large monitors </li></ul></ul><ul><ul><li>Computers </li></ul></ul><ul><ul><ul><li>Codec required to convert and compress analogue video images and sound waves into digital signals to transfer over digital telephone lines </li></ul></ul></ul><ul><ul><ul><li>High-bandwidth required (at least ISDN) </li></ul></ul></ul><ul><ul><ul><li>Bandwidth is a measure of how much data can be passed down a line </li></ul></ul></ul>