FUNDAMENTALS OF DATA COMMUNICATION

Here we shall learn the basics of Data Communication. Many services and products that we use everyday employ computer networks and data communications in one way or another. Telephone systems, banking systems, cable television, audio and video systems, traffic control systems and wireless telephones are just few examples. Here we shall briefly describe about the data and signal which are the basic units of data transmission. We shall briefly cover about the methods for sending the signal over the different networks i.e., synchronous and asynchronous communication. We shall also discuss about the modem, its functioning and different modes of transmission of data.

We have learnt about the two building blocks of communication i.e., data and signal. All data transmitted over any communications medium is either digital or analog. Data is transmitted with a signal and it can take any from either digital or analog. Noise and attenuation are two most important factors which affects the transfer of a signal over a medium.

Any communication system mainly consists of three parts: transmitter, channel and receiver. The device which sends a data or signal is called as a sender. The medium used for the transmission of this signal is called as communication channel. The device or party which receives the signal or data is called as receiver. Asynchronous (character framed) and Synchronous (message framed) are two major data formatting methods that are used to make sure the transmitting computer and the receiving computer are synchronized.

For transmitting a digital data over analog network, signal is required to be converted to analog using a technique called modulation and conversion of analog signal back to digital signal is Demodulation. Modem is device which is an acronym for Modulator Demodulator. Basically, it is used to connect your computer to Internet over a telephone network. Modem design depends on nature of transmission, mode of transmission, type of communication channel, type of modulation / demodulation used. Basically, modems are of two types: Internal modem and external modem.

Internal modems are hardware boards you plug into an expansion slot in your PC's system unit; where as External Modems are connected to the PC by plugging a cable into a port on the system unit. Modem communication parameters includes transmission speed, transfer protocol, data format etc.

Speed of data transmission plays a major role in data communication. Data transmission mainly depends on Bandwidth. Bandwidth is a data transmission rate that tells the maximum amount of information (bits/second) that can be transmitted along a channel. Broadband is often called "highspeed" Internet, because it usually has a high rate of data transmission.

There are 3 basic modes of communication i.e., Simplex mode, half duplex mode, and full duplex mode. In simplex mode of data communication, data travels only in one direction i.e., from sender to receiver. Keyboard is an example of simplex communication. In this mode of transmission, data is transmitted in both the directions but at the same time when the one device is sending data to another then the other device has to wait. In full duplex mode of data transmission data is transmitted in both the direction simultaneously.

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