communication n.
Skip this Video
Loading SlideShow in 5 Seconds..
Communication PowerPoint Presentation
Download Presentation


248 Vues Download Presentation
Télécharger la présentation


- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

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

  3. 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

  4. Network 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

  5. Network 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)

  6. 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

  7. 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 • Fibre –optic cable • Microwave links

  8. Bandwidth: How your internet speed is affected • The term bandwidth refers to the speed at which information is passed over a network like the internet. The higher the bandwidth the more information can be passed through a network at once. • Imagine your internet connection is like a bottle neck or a pipe. The faster the internet connection, the bigger the pipe – so more can fit down it. • Measured in bits per second (bps), millions of bits per second (megabits per second, or Mbps) or billions of bits per second (gigabits per second, or Gbps).

  9. 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) • (Modem – converts analogue to digital)

  10. Computer Networks • A computer network is a collection of computers linked together so that they can communicate with each other • A computer that is not connected to a network is called a stand-alone computer • Connecting a peripheral physically to a computer is made through a port • There are two different sorts of computer network: • ‘Local Area Network’ - the computers are all in the same building or in different buildings on one site permanently connected to each other with special cables. • ‘Wide Area Network’ - the computers are spread over a large geographical area not permanently connected to each other communicate using telephone lines, radio transmitters or satellite links.

  11. Advantages of a LAN • Workstations can share peripheral devices like printers. This is cheaper than buying a printer for every workstation; • Users can save their work centrally on the network’s file server. This means that they can retrieve their work from any workstation on the network. They don’t need to go back to the same workstation all the time; • Users can communicate with each other and transfer data between workstations very easily; • One copy of each application package such as a word processor, spreadsheet etc can be loaded onto the file server and shared by all users.

  12. Disadvantages of a LAN • Special security measures are needed to stop users from using programs and data that they shouldn’t have access to; • Networks are difficult to set up and must be maintained by skilled ICT Technicians; • If the file server develops a serious fault all the users are affected, rather than just one user in the case of a stand-alone machine.

  13. Network security measures • To protect programs and data • Main threats come from other users and hackers • Data can be kept secure by giving each network user their own user identity and password • Unauthorised access can be reduced by allowing different users different levels of access

  14. Wide Area Network (WAN) • Computers in a wide area network are often connected to each other using telephone lines. • When a computer uses an ordinary telephone line to connect to another computer, a modem is needed at each end of the link. • If an entire LAN needs to be connected to a WAN a special gateway needs to be set-up.

  15. 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 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 Advantages No need for cabling Computers can be used anywhere within range of the signal

  16. 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.

  17. Devices

  18. 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.

  19. 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 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 Need to be connected to a device

  20. Subject Attachments: The sender types a short description of what the email is about. The sender can attach files of almost any format to the email. To….The sender of the email enters the email address of the recipients here. Cc…: Carbon copy: The server enters the email address of the people receiving the email for information purpose only Bcc…: Blind carbon copy: The sender enters the email address of people receiving a blind carbon copy of the email. These recipients will not see any of the other recipients email address.

  21. Videoconferencing The use of a computer to send sound and video images from one computer to another in real time. To videoconference you need: • This technology allows people to see and interact with one another in real time at a personal level. • Video conferencing helps collaborate on projects. The screen can be used to share applications like a whiteboard and each member of the conference can contribute by writing on the whiteboard.

  22. Advantages of video conferencing • There is no need to spend time and money travelling to meetings. • You can have a 'meeting' with people from many different offices /countries without any of them having to travel. (Collaboration) • You can see people as well as hear them. This means you can see their body language which you can't do with a telephone call. • You can all view a document on the screen at the same time. People can work together and add their ideas. The document can be emailed to all of the people at the meeting later on. • Ideas and knowledge can be communicated between all those at the meeting very quickly and responses gathered. Video conferencing is good for 'brainstorming'. • Visual and audio contact means more realistic meeting. • Meetings can be arranged at short notice. • Full multimedia presentations by using the applications sharing tool.

  23. Disadvantages of Videoconferencing • Everyone who is going to 'attend' the meeting needs access to suitable hardware and software. This can be expensive and can take a while to set up. • A very reliable, fast data link is needed. Many companies hire a connection specifically to allow video conferences to take place • Even with a fast connection, there might be a slight delay between responses. • If the hardware breaks down for any of the participants, they cannot 'attend' the meeting • People could be in different time zones around the world. This might mean that some people have to stay up through the night in order to 'attend' the meeting. • The video camera might not be able to see all parts of the room at the same time. Some people might not be easy to 'see' at the meeting. • There is no substitute for a face-to-face meeting.

  24. Equipment needed for video conferencing • Video camera • Webcam • High bandwidth telecommunications line • Video conferencing software • A screen • Sound system • Microphone

  25. 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.

  26. 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 managers to monitor and control the workforce

  27. 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

  28. Telephone • The person must be available to take your telephone call. • The line might be engaged when you call so you can't speak to the person when you want. • You have to pay for every minute you spend on the call. In the case of mobile or overseas calls, that can be expensive. • There might be noise or interference so the quality of the call could be poor. • With mobile calls you might move out of the range of a transmitter and so the call gets cut off. • You cannot see each other's body language so a lot of the non verbal communication is lost. • It is not easy to make a record of what is said during the call. Things might be forgotten or mis-interpreted. • Only spoken information can be exchanged - you can't send files.

  29. Mobile Phones • Uses radio frequency to transmit data. • Can be carried around easily and used anywhere that has network coverage.

  30. Using a mobile phone to access the internet • WAP enabled mobile phones can be used to access the internet. • WAP – Wireless Applications Protocol, this was designed to allow handheld devices to access the internet. • WAP phones can be used to: - View train timetables - Send and receive email - View traffic information - Look up sports results - Check weather conditions

  31. Using a mobile phone to access the internet (cont.) • Handheld devices such as PDA’s (Personal Digital Assistants) are also WAP enabled. • One of the most up-to-date handheld devices is the blackberry. • It allows users to access email and even download attachments as well as being able to use the phone.

  32. Short Message Service - SMS • This is the text message facility associated with a mobile phone. • Done almost instantly. • A text message can get through even when a call is in progress. • A text message goes to the central message centre and it is forwarded as soon as a transmission space is available. • The message function can also be used to send emails and fax messages. • Email can be sent buy SMS through a gateway. The gateway converts the SMS to email format and the provider will forward the email to the recipient. • Mobile phones can roam. This means they can send and receive data and telephone calls whilst being in another country. • If people are away from home a lot, they can be kept up-to-date on all current information.

  33. Bulletin Board • A Bulletin Board is an area online that allows you to view and post messages. • It is also called a Forum or Message Board or Discussion Board. • Usually anyone can view the messages, but if you want to 'post' a message then you will need to sign in so you have a name on the Forum. • The starting message has a topic title . You can see a message above with the topic "edexcel 1185 GCSE". • When people reply to the message, a thread begins to form. This is a string of related messages. See a typical message thread below.

  34. Instant Messaging • This is mostly a text based service, where one person types a message and the other person immediately sees it pop up in their IM (Instant Message) window. • Groups can also be set up so that a number of people can chat to each other whilst online. • Each person must have an 'Instant Messaging' (IM) client open on their computer. • The way it works is very similar to email, because both IM and Email client software need to connect to a server in order to work. • Users can communicate instantly. • When a user types a message all of the users logged in can see the message instantly. • Microsoft designed MSN for instant messages and it is used throughout the world as a means of communication.

  35. Instant Messaging (cont.) • The difference between email and Instant Messaging is that the IM window shows the message almost as soon as it is typed - no downloads are required. • This kind of service is used by business people to help keep in touch whilst on the move. Imagine a work colleague is at the airport waiting for a plane connection, they can use Instant Messaging to 'talk' to colleagues in the office - it is a good way to keep on working (and avoid the sheer boredom of waiting for a plane!) despite being away from the office.

  36. Communications – Monitoring and Tracking Systems