DCN | Lecture 1 | Data Communication and its System Components

DATA COMMUNICATIONS -

Data communications are the exchange of data between two devices via some form 

of transmission medium such as a wire cable.

* When we communicate, we are sharing information.

* This sharing can be local or remote.

* Between individuals, local communication usually occurs face to face, while 

   remote communication takes place over distance.

* The term telecommunication, which includes telephony, telegraphy, and 

television, means communication at a distance (tele is Greek for "far").

* The word data refers to information presented in whatever form is agreed upon by 

the parties creating and using the data.

* For data communications to occur, the communicating devices must be part of a 

communication system made up of a combination of hardware (physical equipment) 

and software (programs).

Data Communication System Components

Message:- The message is the information (data) to be communicated. Popular forms of information include text, numbers, pictures, audio, and video.

Sender:- The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, video camera, and so on.

Receiver:- The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, television, and so on.

Transmission medium:- The transmission medium is the physical path by which a message travels from sender to receiver. Some examples of transmission media include twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves.

Protocol:- A Protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating, just as a person speaking French cannot be understood by a person who speaks only Japanese.