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  • Created by: Isabel N
  • Created on: 17-05-16 17:10

Digital Communiations

  • LAN (Local Area Network) - Can connect all the computers in one location
  • WAN (Wide Area Network) -  Connects users over a wider area, such as a company with offices in different cities.
  • This can be done using wired or wireless technology

Home Network: Multiple users can interact, use internet at same time, can share resources and peripherals. However, specialist equipment is needed, special knowledge is required to set up, cables could break, causing the network to fail, and the wireless signal could be unstable.

Bandwidth: Capacity of connection, measured in Mb/s

Latency: Connection speed. Measured in ms. Lower number = faster speed.

Ethernet Cable: Computers connected with a cable. Each computer needs and ethernet card (cable plugs in to it), speed influenced by type of Ethernet Card installed. Card have different speeds, some faster than others.

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Digital Communications/Digital Data

Wireless: Each computer needs a wireless card, wireless router needed (transmitter that pick up signal), operates over limited distances, transmission affected by other devices/obstacles in home, such as telephones or walls.

Powerline: Data Transmitted by using power circuit in the home, send signals through mains wiring system, connects computer directly into normal plug socket.

Speed of Data Transfer

  • Bandwidth: Data transfer rate per second, measured in bytes/s, high bandwidth needed if you want to stream video
  • Latency: Refers to time taken to send data from one destination to the another. The greater the latency, the longer it takes to send data.
  • To connect to the internet, the user needs a broadband connection. Fast seed achieved by fibre-optic cables.
  • ADSL (Asymmetric Digital Suscriber Line) offers even faster speed, as it uses telephone lines, but splits the signal to separate it from voice calls. Not all phone lines allow this.
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HTTP (Hyper Text Transfer Protocol): Main protocol of WWW, defines how web servers deal with commands so they can go and find a web page, allows linking and browsing to take place.

HTTPS (HTTP, with Secure Socket Layer): Ensures Internet transactions are safe and secure, when seen in browser address bar, it means your connection is secure.

POP (Post Office Protocol): Used when downloading/recieving email messages from your ISP (Internet Service Provider) to email software on computer, doesn't apply to webmail recieved in web browser by server.

IMAP (Internet Message Access Protocol): Used when recieving email addresses.

SMTP (Simple Mail Transfer Protocol): Used when sending email messages via mail server from computer.

VoIP (Voice over Internet Protocol): Allows phone calls to be made over the internet, turns analogue signals into digital ones so they can be sent over the internet.

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Browsing the Internet

  • ISP (Internet Service Provider) provides you with a range of services for a cost: Monthly charge, webspace, e-mail account, download data, security firewall.
  • Firewall prevents unauthorised access to your computer.
  • Spyware is a type of software that can be installed on your computer without your knowloedge or consent. 'Spies' on your activities and can collect security data (passwords). Can then be used by other people to access your account
  • Malware forces unwanted pop-ups to appear on your screen and change your toolbar.
  • Free download websites are illegal - most files need to be paid for befor you download them
  • Peer-to-peer websites are a breach of copyright because they share files illegally
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