Communication

1. One of the most important ways that information technology is used today is to distribute, exchange and share information. Electronic communication systems are what we use to do this. The most widely used forms of electronic communication are e-mail, videoconferencing, computer networks and the Internet. Communication

2. Networks: LANs What hardware do you need for a LAN network? • File Server : Runs software, stores files. • Terminals : Workstations that give network access. • Print Server : Queues up all print jobs from users in network. • Cables (wire/optic) : Sends data • HUBS – joins computers in a network • Router – enables network to be connected to the internet (SKY Router)

3. Interfacing Computing peripheral devices work differently. When a device is connected to a computer, an interfaceis the hardware and software needed for the processor to be able to communicate with the device Sometimes the interface hardware comes on an interface board, which has to be fitted into the computer. (Graphics Card, Network Card)

4. Interfacing Commonly the peripheral is just connected via a socket This is the port through which signals to and from the device travel • Serial/parallel • USB • Firewire • HDMI • MIDI • VGA

5. Handshaking When two devices need to communicate, one device sends a message to the other • “are you ready to receive data?” When the other is ready, it sends a signal back to the first device • “Yes I am ready to receive data” Now the communication can begin This exchange of preliminary signals is called handshaking

6. Networks Protocols Protocol: A set of rules for transmitting data across a networkable to 'talk' or 'communicate' with one another and they do this by following a protocol. Protocols have rules for • Detecting a connection • Handshaking • How to start a message • How to format a message • What to do about errors • How to detect a loss of connection and what to do next • Terminating a connection

7. Networks Protocols HTTP: HyperText Transfer Protocol • Used for transferring web pages between a client and a server on the Internet FTP: File Transfer Protocol • Used for transferring files from one computer to another – uploading a web page to a web server SMTP: Simple Mail Transfer Protocol • Used for sending an email over the Internet (Whatsapp) VoIP: Voice over Internet Protocol • Used for sending voiced messages over the Internet (Skype)

8. Networks Protocols • Wireless - WAP • WAP stands for Wireless Application Protocol and is a popular type of mobile internet service which can be used on a handheld device, such as a mobile phone or PDA. It enables you to go online while out and about and is especially handy if you want to get the latest news updates, sports scores and travel updates. (Apple phones communicate with Android) • 3G and 4G taken over

9. Broadband Broadband is the name given to a data communication channel that has a wide bandwidth and can carry a large quantity of data. Many UK schools are now connected to the Internet using a broadband connection with typical data speeds of 2Mbps. This connection could be by: • Copper wire using ASDL connections • Fibre –optic cable • Microwave links

10. Wireless Networks Radio waves can be used to transmit data from one computer to another Each computer in a wireless network requires a wireless network cardtogether with the software drivers Awireless hub is connected to the network and transmits receives data from the computers

11. Wireless Networks - Advantages No need for cabling Computers can be used anywhere within range of the signal

12. Wireless Networks - Disadvantages Data transmission speeds can be slow Data signals can only be received within a limited range Securitymaybe a problem as people may be able to pick up the data signals outside of your premises

13. Network Security There are many ways to secure a network ranging from complicated around the clock security services to a simple lock and key. Physical security means that the hardware of the network is protected from theft and kept safe. Access security means that there is a limit to the amount of access a user has to the information held on the network. Data security means that there are measures taken to prevent the loss of data held on the system.

14. Devices

15. Faxes A fax machine scans paper documents and converts them into digital format. The digital version is then converted into analogue format and sent over an ordinary telephone line to another fax machine. The fax machine at the receiving end converts the analogue information back into digital format and reproduces an exact hard copy of the original document. Faxes are particularly useful for transferring images or documents when it is important that an identical copy of the original is received at the other end.

16. E-mail Used to send messages from one computer to another Can be sent between computers on a local area network or between computers on the Internet Advantages of e-mail: Arrives at its destination in at most a few hours Send and receive e-mail anywhere in the world, at any time One e-mail message can be sent to a group of people Can be cheaper than sending mail through the post Can attach a file

17. Disadvantages of e-mail Some workers receive so many e-mails that they are unable to answer them all Computer viruses are often sent by e-mail Can send junk mail just as with conventional post

18. Videoconferencing The use of a computer to send sound and video images from one computer to another in real time. To videoconference you need: • A computer with a large memory and a fast processor which can handle the large amount of data that video pictures contain • A digital video camera to capture the video pictures at your end of the link • A microphone or telephone hand-set to capture the sound that goes with your pictures; • Access to an ISDN telephone line. This is because ordinary telephone lines weren’t designed to cope with the large amount of data that needs to be sent along them for videoconferencing; • Special videoconferencing software.

19. Advantages of videoconferencing You can communicate with other people over long distances and see them as well as hear them Videoconferencing is more personal than just a telephone call Businesses can use videoconferencing to hold meetings which many people can be involved in There is less need for people to travel

20. Disadvantages of videoconferencing The hardware and software needed are very expensive Not many people have videoconferencing systems ISDN lines are needed which are expensive to set-up and use There is no substitute for a face-to-face meeting.

21. Teleworking Telecommuting is when people work from home instead of travelling to work and use methods of electronic communication such as the telephone, fax machine, e-mail, the Internet and videoconferencing to communicate with the outside world. Advantages: • Time isn’t wasted travelling to and from work; • Cars are kept off the roads which helps the environment; • Working at home is less stressful and it is much easier to concentrate; • Working hours are more flexible and can be fitted around other things that need doing such as collecting children from school; • People who live large distances away from each other can work together without having to meet in person; • Businesses need smaller offices and spend less on light and heating.

22. Disadvantages of Teleworking Workers may miss the company of their co-workers and feel isolated Having your workplace at home might mean that you end up doing too much work and not having enough time off It is more difficult for mangers to monitor and control the workforce

23. Digital TV V Analog Conventional TV is transmitted using analogue signals Digital signals are used to transmit digital TV channels – digital signal is decoded so that normal TV shows the images and sounds – done by using a decoding box – eg Sky

24. Digital V Analogue TV Digital TV signals can be compressed easier than analogue signals; therefore the amount of data which can be sent on a digital signal is much greater Digital communications lines can transmit and receive data; therefore digital TV can be interactive Analogue TV can suffer interference. Digital TV is less affected by interference, so the digital channel will provide a sharper, clearer picture Digital TV outputs high quality stereo sound using MPEG technology More channels are available on digital TV because of the larger bandwidth available Digital TV allows viewers to look at pictures from different camera angles