Data Communication/ Data Transmission

by • 17/11/2012 • GeneralComments (0)603

Data Communication/ Data Transmission

Data Communication/ Data Transmission is a process of sending data electronically from one point to another by linking one computer to another. Computers that are physically close to each other, either in the same room or building, can communicate data through a direct-cable link. This is done by two main ways, through modems and through networks. Modems enable computers to use telephone lines, cellular connections (that a cell phone uses), or satellite links to connect to other computers. Whereas, networks connects computers directly either through special wires or by wireless transmission.

Forms of Data Transmission

The two forms of Data Transmission are:


1. Analog Data Transmission

It is transmission of data in continuous wave form. The telephone is an example of a system designed for analog data transmission.


2. Digital Data Transmission

It is transmission of data in distinct on and off electrical states. The data in digital form are represented as a sequence of 1s and 0s. Modem, explained below, is an example of digital data transmission.


Modulation -Demodulation

Analog data transmission is used for a great percentage of data communication and it is the largest and most widely used communication system already in place. To avoid the expense involved in converting to a digital system or running a duplicate digital system over a large geographic area, a method was devised to transmit digital signals over telephone lines as modulator-demodulator.

The telephone system, an analog data transmission, was designed to transmit the human voice; they format data as analog signals. For communication to take place over a telephone line, the digital signal must be converted to an analog signal before it is transmitted by a computer. This process of conversion of a digital signal to on analog signal is called modulation.


Bock to receive the signal by the computer, the analog signal then reconverted to digital signal. This process of reconversion of on analog signal to a digital signal is called demodulation. The device that accomplishes both of these processes is a modem, short for modulator-demodulator.


Types of a Modem

There are three basic types of modems used with computers are:


1. Acoustic modem

This type of modem sends data through the mouthpiece and receives data through the earpiece of the handset.


2. External direct-connect modem

This type of modem connects to the telephone line directly with a modular phone jack. This direct connection greatly reduced the distortion of the signals and permits foster data transfer rates. Because it is placed outside of a computer, it is called External.


3. Internal direct-connect modem

This type of modem also connects to the telephone line directly with a modular phone jack. Because it is placed inside of a computer, it is called Internal; therefore, they take no desk space and are ideal for use in portable computers. With his slipshod talk and caustic tongue, there was the main trunk

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