Communication Systems

www.ICT-Teacher.com

The Internet

• The largest wide area network in the world. It is made up of thousands of linked networks.

• What is a Network?• Two types of networks WAN, LAN what is the

difference?• How many people globally are connected to

the Internet?• What are the hardware requirements for

accessing the Internet?• A computer, a modem or router, a telephone line

or broadband connection, Internet browser software.

Costs

• Hardware, Software.

• Subscription to an Internet Service Provider (ISP), and free calls.

• A call charge for every call at a local call charge for any web-site anywhere in the world.

• A quarterly rental charge with a company such as British Telecom.

Speed

• Speed is determined by:• Modem speed, standard is 56kbps, but the

effective transfer is much lower.• The bandwidth of the communication line,

telephone is standard, much faster speeds are achieved by using cable and ISDN.

• The amount of other users on the network (communication lines).

• The type of data being accessed, text is fast as it uses little memory, graphics use greater amounts of memory and are slower.

World Wide Web

• The world wide web is how people access and upload data to and from the Internet.

• HTTP is the language used to develop the data that is available. What is a hypertext link?

• The WWW is accessed using a web browsing software program.

• How does it assist in finding a particular web page?

• What are the different purposes of the world wide web (why do people use the web)?

World Wide Web

• Accessing and downloading information from the Internet in the form of:– Text,– Images,– Sound,– Video.

• E-mail • Instant messaging (MSN)• News groups (Facebook)• File Transfer Protocol (FTP) (file exchange)• Peer to Peer file exchange (Mp3 music files)

On-Line Information Services

• Information Service provided by e.g. BT.• Subscribers gain access to the latest news,

weather, sports, fashion etc.

Electronic Bulletin Boards

• An Internet site for groups with similar interests for information exchange.

• Used for thousands of special interest groups, it can be open to misuse, why?

Intranet• An Intranet is a private

network used by organisations on their network that uses the same standards as the Internet – HTTP, FTP, and e-mail.

• The new Learning Gateway is an example of an Intranet, when you can access from outside the school it will be an Extranet.

Extranet• The Intranet is restricted to use within the organisation,

and extranet is available to associated people from outside the organisation provided they have been given access by means of user names and passwords.

• This requires more security than an intranet as people who access it from outside are using the public telephone service and the Internet.

• When the Learning Gateway is accessible from home it will become an extranet.

• People with access rights can see their own files and homework set – the students.

• People without access rights only see the pages that are available to the public.

Extranet showing access by outlying offices.

Firewall

Extranet on company’s main server

E-mail

• What is e-mail?• What types of documents can be sent using

e-mail?• What are the advantages to ordinary mail?• What could be a problem with e-mail?

Telephone Technology

• Why are the old telephone networks still so important?

• What are some of the facilities that BT provide?– Consider: caller identifier, ring back, directory

services, automatic call logging, digital remote handsets, three way etc.

• What is a Fax machine?• How do they work?

Mobile Telephones

• How widespread are mobile ‘phones in this country and globally?

• What are some of the new features of mobile ‘phones?

• What is Voice mail, and some of the services it delivers?

Teleconferencing

• What is teleconferencing?• What is videoconferencing?• What devices are necessary for

videoconferencing?• Why is ISDN (Integrated Services Digital

Network) used to transmit video?

ISDN

An essential tool for correspondence, marketing, feedback and support.

• What are the opening hours for business on the web?

• What are the procedures for purchasing a music CD on the Internet?

• Why is it normally beneficial for a customer to use the Internet for making a purchase?

• What are the advantages for the business?• What could be the disadvantages for the

business?• Some customers may be worried about

purchasing goods on the Internet, why?

Business to Business

• Why would businesses use the Internet to trade between each other?

• How can the Internet be used to find new suppliers?

• If you were a web developer for a small business what are the main features you would include on the web-site?

• What would the benefits be and for whom?