Some important definition of E-communication

Communication: Communication means passing data/info from one place to another.

Electronic Communication: Electronic communication means passing data/info through electronics means signal.

Data: Generally and in science, data is a gathered body of facts. In computing
data is information that has been translated into a form that is more convenient to move or process. In telecommunication data sometimes means digital encoded information to distinguished from “control information”, “control bits” and similar terms to identify the main content of a transmission unit.

Information: Information is stimuli that has meaning in some cotext for its receiver. When information is entered into and stored in a computer, it is generally referred to as data. After processing output data can again be perceived as information.

Block diagram of a basic communication system----

Transmitter

i) Transducer,

ii) Modulator,

iii) Amplifier,

iv) Antenna

Transducer: A transducer is a device that converts one type of energy to another. This conversion can be to/from electrical, electro-mechanical, electromagnetic, photonic, photovoltaic or any other form of energy.

Modulator: Modulation is the process of conveying a message, for example: a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted.

Communication channel: Channel in communications refers to the used to convey information from sender to a receiver.

Repeater: Repeater regenerates incoming electrical wireless or optical signals.

Antenna: The amplified and modulated signal to be spread by an antenna.

Network: A network is a series of points on nodes interconnected by communication paths.

Computer Network: Where many computers are connected by wire.

LAN: Local Area Network. Where many computers are connected in a small area.

MAN: Metropolitan Area Network. Many LAN makes a MAN.

WAN: Wide Area Network. It’s a geographically dispersed telecommunications network.

Internet: Network of networks.

Topology: Topology is the physical layout of a network.

Classification of Topology:

i)                  Mesh topology,

ii)                Bus topology,

iii)             Star Topology,

iv)              Ring Topology.

i) Mesh topology: Where each pc connected with another. P-2-P connection present. Dedicated connection. Facility: If one link fail to communicate with another then only that link would be disconnected.

ii) Bus topology: Where all devices or PC-s are connected with a backbone-line by a drop-line and tap. It used in broadcast network. Probs: There is much flooding. So data can be lost.

iii) Star topology: Every PC linked at one point i.e. HUB. There is P-2-MP connection present. If the connection of HUB is failed then total network connection will be failed. HUB should have the intelligence about communication (Where it has to send the data getting from a PC)

HUB: HUB is a device which can connect many7 PC-s together.

HOP: On the way of going to receiver from terminal what stays on the way is called hop.

Multi-hop: Where every hop works as repeater.

Half Duplex: Only can send or receive data at one time.

Full Duplex: Both send and receive data at the same time.

Protocol: A protocol is the special set of rules of telecommunication connection use when they communicate.

Internet Protocol: Internet protocol is the method or protocol by which data send from one computer to another on the internet.

OSI Protocol Layers;

ü    Application layer

ü    Presentation layer

ü    Session layer

ü    Transport layer

ü    Network Layer

ü    Data link layer

ü    Physical layer

Way to remember the sequence: Please Do Not Take Sauce And Pizzas Away.




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