DATA COMMUNICATION

Data Communication

     Data communication is the exchange of data between two devices through some transmission mediums, like a cable wire in the form of 0's and 1's. The purpose of data communication is to exchange information between two agents (end stations or nodes). End station may be a general purpose computer, a workstation, a cell phone or a PDA (Personal Digital Assistant). Users depend on nodes for transmitting or receiving digital information. Digital techniques and digital equipments  are used in a data communication circuit. Transmission facilities are usually provided by a public telephone network (PTN) or Public Data Network (PDN).

[Source] --- [Transmitter] --- [Transmission Channel] --- [Receiver] --- [Destination Software]





Source

     Source may be a digital equipment or an application software running on a computer through which the user enter data into communication system for transmission to a remote host. Example of such an application software is the Internet Explorer.

Transmitter

      Source data should be converted into a suitable format before it is transmitted through a channel or medium. This conversion is done by the transmitter. If the transmission channel is an OFC (Optical Fiber Cable), digital signals should be converted into optical signals. This conversion process is usually termed as encoding. Thus, transmitter acts as an interface between source device and transmission channel.

Transmission Medium

      The facility through which encoded signals travel from source to receiver is termed as a channel or transmission medium. Both guided media and unguided media are available. Metallic cables, UTP (Unshielded Twisted Pair) cables and OFCs belong to the category of guided media. Satellite radio and cellular networks belong to the category of unguided media.

Receiver

      The encoded signals received from the communication channel are converted back to the original format. This action may be termed as decoding. The decoded signal is given to the appropriate destination device or application software.

Destination

The user at the destination gets the data/information through destination device or software.

Point-to-Point

In this type of connection, there exists a dedicated channel between two end devices.

Multi-point

     In this connection, a single communication channel or link will be shared by many users in the network. But, a single point link failure will affect all the devices connected to the link.

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