Data communication is the process of transporting encloseddata from one location to another using any transmission mediawithin a network. A communication system consists of five basiccomponents, which are

• The Sending or Originating Computer: The originating computer orterminal hosts the data to be transmitted. The data may consist ofa file on a disk or may be entered through a keyboard andtransmitted as it is typed.

• Data Encoding Device: This device is attached to the sendercomputer. This converts the data into a form in which it can betransmitted over the communication medium.

• The Communication Channel (Link): This carries the encoded datafrom source to its destination, e.g. Telephone Lines, MicrowaveRelay Systems.

• Data Decoding Device: This device is attached to the receivingcomputer. This device converts the received data into a form that thereceiver computer can understand and process.

• The receiving computer or terminal which receives the data &displays them on a screen, prints them, or stores them in a file.

Computer communication is important for following reasons:

• Sending and receiving data at a very high speed is required intoday’s scenario.

• Connection between two different departments from largedistance offices in an organization is possible due to computernetwork.

• Update on stocks and international market price is possiblethrough the computer communication.

The core of the Co-axial cable consists of a solid copper wire,which is surrounded by an insulating material. A cylindrical conductorencases the insulator and the outer conductor is covered in aprotective insulating sheath. They consist of central copper wiresurrounded by PVC insulation over which a sleeve of copper mesh isplaced. It can be used for both analog and digital transmission andprovides a high performance communication path for applications,requiring bulk transmission of data at high data transfer rate.

Co-axial cables offer higher bandwidths and are capable oftransmitting digital signals at very high rates of 10 Mega bits persecond. They are extensively used in long distance telephone linesand as cables for closed circuit TV They are also used by telephonecompanies to transmit data.

These systems use very high frequency radio signals for transmissionof data through space. Data may be transmitted along aground route by repeater station which receives the data, amplifies itand again retransmitted along.

Latest development on technology has made it possible totransmit data using pulses of light. A light pulses can be used torepresent one binary value by presence and another binary value byabsence of the pulse signal.Optical fiber provides high performance capabilities of widebandwidth, high noise immunity, and long distance spacing betweensignal amplifiers. The bandwidth of an optical transmission system isextremely large.