USE OF COMPUTER IN COMMUNICATION

Computers are extensively used in sending and receiving information.The information transfer may take place either between two points or throughout a computer network that connects a number of computers or workstations.Data communication packages are available which are used to send and receive information.For communication purpose one must have a computer,a data communication package and a modem.Usually,telephones lines are used over which data are transmitted from one place to another.

The telephones lines are used over which data are transmitted from one place to another.The telephone lines have been built for voice transmission.To transmit human voice continuously variable analog wave patterns are used.Thus a telephone line is designed to transmit analog signals.on the other hand,a computer processes digital signal consisting of pulse or no pulse,i.e presence or absence of an electrical voltage.Digital signals can not be transmitted over existing telephone lines which have been designed to transmit analog signals.Hence,modems are needed to convert or modulate digital signals to analog signals and vice versa when exiting telephone lines are to be used.A modem connects a computer to the telephone lines.The modem receives data from a computer or a terminal which are to be transmitted over telephone lines.The modem converts(modulated) the digital signals into analog signals which can be transmitted over the telephone lines.The modem at the other end receives the data from telephone lines and converts (or demodulates) the received analog signals into digital signals.These digital signals are processed by a computer at the receiving end and they are reproduced as the original information.Data can be transmitted in both directions.A modem performs both tasks:modulation and demodulation.when data is being transmitted from an end,the modem placed at that end performs modulation.when data is received at an end the modem placed at this end performs demodulation.