Role of Communication Systems

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