Section 4: Applications and Implications of Information and Communication Technology Flashcards
Data Communication
This is the transmission (movement) of data from one point to another for direct use or for further processing e.g. from one computer to another, from a cell phone to computer or vice-versa, or from a computer to fax machine.
Bandwidth
The volume of data that can be transmitted in a given time.
Narrow-band
A Narrow-band channel transmits data at a slow speed of about 10 to 30 characters per second (cps). An example of this is the telegraph system
Voice-band
A Voice-band channel transmits data at a rate of 1000 to 8000 cps. An example of this is the telephone line.
Broadband
A Broadband channel transmits large volumes of data at speeds of over 100 000 cps. An example of this is a communication satellite, fibre optic cables, coaxial cable, microwaves.
Transmission media
These are the ways and/or materials used to move data. Media can be cabled/wired or wireless.
Twisted pair cable
Used for home networking where there is no great need for speed. It is a cheap convenient method of connecting computers and peripherals in a network.
Coaxial cable
Used in medium-sized networks to transmit voice, video and data at moderate speeds. This is more expensive than twisted pair because the transmission capabilities are higher.
Fibre optic cable
Used to transmit large volumes of digital data at extremely high speed virtually error-free. These are relatively expensive.
Communications satellite
Communications satellite is a space station that receives microwave signals from an earth-based station, amplifies (strengthens) the signals, and broadcasts the signals back over a wide area to any number of earth-based stations.
Microwaves
Microwaves are radio waves that provide a high speed signal transmission. It is also called fixed wireless and involves sending signals from one microwave station to another. A microwave station is an earth-based reflective dish that contains the antenna, transceivers and other equipment necessary for microwave communications.
Infrared
Infrared is a wireless transmission medium that sends signals using infrared light waves. Mobile computers and devices , such as mouse, printer, and smart phones often have IrDa ports that enables the transfer of data from one device to another using infrared light waves.
Hot spot
Hot spot is a wireless network that provides Internet connections to mobile computers and other devices. They are used by mobile users to check e-mail, browse the Web and access any service on the Internet.
Bluetooth
Bluetooth is a standard developed by electronic manufacturers that allow any sort of electronic equipment (computers, digital video cameras, cell phones, PDAs, etc to automatically make their connections without wires, cables or any direct action from a user. One disadvantage of Bluetooth is it cannot transmit signals through walls and distances of over 3 meters.
Wi-Fi
Wi-Fi is short for wireless fidelity. It is a type of broadband Internet connection that uses radio signals to provide Internet connection to wireless computers and devices.
Communication modes
The lines that transmit data are also classified according to the direction in which data flows through them. There are three (3) types of lines:
- A simplex line permits data to flow in only one direction. You can send data or receive data, but not both.
- A half-duplex line can alternately send and receive data. That means that at any particular time you can either send data but not receive it, or receive data but not send it.
- A full-duplex line can simultaneously send and receive data.
Networks
A network is group of two or more computers linked together so that they can share resources (hardware, software and data) and can communicate with one another.
Local Area Network (LAN)
LANs consists of a collection of microcomputers, such as in an office building, department or school that can share peripherals, files and programs and communicate with each other on the network. Each microcomputer that forms part of the network is connected either by cables or by a wireless link.
Wide Area Network (WAN)
This network connects mainframes, LANs and PCs across a large geographical area such as a city, a country or the world using a combination of many types of media such a telephone lines, cables microwave links, satellite links. WANs are used mainly by universities, research centres and large organizations with branches in different countries.
Metropolitan Network (MAN)
This network connects LANs in a metropolitan area such as a city, state or town. It includes one or more LANs but covers a smaller geographical area than a WAN. It is usually managed by a single network provider that sells the service to users. Telephone companies and cable television operators provide connections to the MAN.
Intranet
This network is a micro-version of the Internet within a company or organization. It offers the same features of the global Internet but limited to a small area such as a factory site or an office. Authorized users within the company can use the company’s intranet to find information easily and quickly. The documents in the intranet have links to other documents in the network or outside the wider Internet. This network uses browsers and software just like those used on the Internet.
Extranet
This is an Intranet that allows limited access to it by people outside the company. A company may set up an extranet, for example, to provide technical support information to its customers based on products it sells or services it provides.
