Information and communication technology (ICT)

 

 INFORMATION AND COMMUNICATION TECHNOLOGY (ICT)

Information and Communications Technology (or technologies) is the infrastructure and components that enable modern computing to create, access,analyze and communicate information. Human beings have always accessed information and communication, but what makes these present technologies special is that it has allowed more people to communicate faster and cheaper.ICT system is made up of these components:

(A) Data and information :

Data is simply facts or figures - bits of information, but not information itself. When data is processed, interpreted, organized, structured or presented so as make them meaningful or useful, they are called information. It may be in the form of text, sound, graphic or figure that has been processed in such a way as to be meaningful to the person who receives it.

B. Hardware: 

In information technology, hardware is the physical aspect of computers, telecommunications, and other devices. Hardware are the physical parts or machinery that we can touch. For example mouse, key board, printer,etc.

C. Software:

 A computer needs to be told what to do, software is the applications and programming instructions that tell your computer what to do. Software enable you to use a computer for things such as playing games, writing an essay or listening to music. These are machine-readable instructions that direct the circuitry within the hardware parts to store, process, transmit, receive and retrieve information in a specific manner.

D. Procedures: 

These are set of instructions and rules to design and use information system. These are written in manuals and documents for use. These rules or methods may change from time to time. The Information System must be flexible to incorporate these changes.

E. Human resource: 

It is people who design and operate the software, they feed input data, build the ha rdware. 

FLOW OF INFORMATION

Flow of information is a particular view that focuses on the path and means

followed by information entities.

In telephone, information path is wires in which the information flows by means of

electrical signals. In radio, television and cell phone, information path is either

air, vacuum, and/or seawater in which the information travels in the form of

electromagnet waves or through optical fibres through which information travels

in the form of light. 

Signals are electric or electromagnetic representations of data or information.Transmission is the communication of data/information by the propagation and processing of signals.

Transmission of electrical signal through wire: 

Data or information can

be transmitted and received over a wire-based communication technology. The

information is converted to electrical signals at the transmitter, which is sent through wires (twisted pair, coaxial cable etc.), and information is converted back to original form at receiver's end. Examples include telephone networks, cable television and internet access. For example a simple telephone model sound (voice) is converted

into electrical signals through mouth piece and sent through electrical wires(twisted pair) and converted back to sound (voice) through ear piece at the

receiver.

 Transmission of electrical signal through optical fibers:

An optical fiber (discussed in chapter 12, geometrical optics) transmits a signal-

encoded beam of light by means of total internal reflection. Total internal

reflection can occur in any transparent medium that has a higher index of

refraction than the surrounding medium.

The information is converted into electrical voltage signals, this varying voltage is

used to produce light. Two different types of light source are used in fiber optic systems: the light emitting diode (LED) and the injection laser diode (ILD). Both are semiconductor devices that emit a beam of light when a voltage is applied. The

LED is less costly, operates over a greater temperature range and has a longer

operational life. The ILD, which operates on the laser principle, is more efficient

and can sustain greater data rates the principle of optical fiber transmission.

A. Step-index multimode: 

Light from a source enters the cylindrical glass or plastic core. Rays at low angles are reflected due to totai internal reflection and

travel along the fiber; other rays are absorbed by the surrounding material. This

form of propagation is called step-index multimode. This type of fiber is best

suited for transmission over very short distances

B. Single-mode:

 When the fiber core radius is reduced to the orde wavelength, only a single angle or mode can pass. Single-mode is typically long distance applications, including telephone and cable television.

C. Graded-index multimode: 

When the index of refraction at the centre core is made is higher and reduced gradually, light in the core curves helicat o variation in the index of refraction. The shortened path and higher speed light at the periphery to arrive at a receiver at about the same time as the straight rays in the core axis. Graded-index fibers are often used in Local Area Net(LAN).

Transmission of radio waves through air or space: 

Electrical signals representing information from a microphone, a TV camera, or a computer (transmitters) can be sent from one place to another place using radiowaves.For transmission of a signal, radio-frequency electrical energy from the transmission is converted into electromagnetic energy by the antenna and radiated into surrounding environment (atmosphere, space, water). For reception of a signal electromagnetic energy falling on the antenna is converted into radio-frequency lectrical energy and fed into the receiver.In two-way communication, the same antenna can be used for both transmission and reception.

An antenna can be defined as an electrical conductor or system of conductor used either for radiating electromagnetic energy or for collecting electromagnetic energy.

For example sound waves produced at the radio station changed into electrical signals through microphone. These electric signals are then fed into the transmission antenna which superimposes these electric signals on electromagnetic waves and emits them, in form of radio-waves. At the receiving end, the receiver selects and amplifies this radio wave signal. The receiver extracts the information and converts it to sound with the help of a speaker. A communication satellite is infacta microwave relay station. It is used to link two or more ground-based microwave transmitter/ receivers,known as earth stations, or ground stations. The satellite receives transmissions on one frequency band (uplink), amplifies or repeats the signal, and transmits it on another frequency (downlink). depicts in a general way communications between ground-based transmitter and a number of ground-based receivers.

 (A) Fax machine

A fax machine is designed to send as well as receive documents so it has a receiving part. The sending part a computer scanner, that scans only one line of a document at a time, and only in black and white. A fax machine transmits one kind of electric pulse down the phone line to represent black and another to
represent white.
The phone line transmits this information almost instantly to a fax machine at the
other end. It receives the electrical pulses and uses them to control a printer it
takes about a minute or so to transmit a single page of writing (or a comples
drawing) in very systematic way.

B. Cell phone: 

Wireless phones which receive their signals from towers. A
typically the area (several miles) around a tower in which a signal can be recebe
Cell phones provide an incredible array of functions.
Depending on the cell-phone model, you can:
*Store contact information
* Make task or to-do lists
* Send text messages
*keep track of appointments and set reminders
* Use the built-in calculator for simple math
* Get information (news, entertainment, stock quotes) from the internet
* Send or receive e-mail
•**Customizable Operating Systems (Oss - software that allows users to interact
with the computer system)-enable the user to download apps (computer program
designed to run a mobile device such as phone/tablet or watch) like games, GPS,
watching TV, utilities, and other tools. Android, a mobile OS developed by Google,
is the first completely open-source mobile OS, meaning that any cell phone
manufacturer can use it in their phones for free.