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What is Data Communication?Data Communications: What is Data Communication?Communication means the exchange of information or messages. When we talk with each other, we are exchanging information. Data communication is the exchange of data between two devices (computers) via some form of transmission medium such as wire cable, wireless system, microwave system, satellite system etc. The communicating devices must be the part of a communication system. The communication system may consist of hardware and software. In data communication process data is transmitted electronically from one system to other system using standard methods. The data transmitted from one place to another in form electromagnetic or light waves through communication medium. The electromagnetic or light waves representing data are called signals. Data communication signals can be in analog or digital form. Therefore, data transmission is divided into:
1. Analog Data Transmission The transfer of data from one place to another in the form of analog signals or in the form of continuous waves is called analog data transmission. The analog signal consists of a continuous electrical wave. The light waves, sound waves or radio waves are examples of analog signals. The transmission through telephone line, microwave system or satellite is the example of analog data transmission. An analog signal is shown in figure below.
2. Digital Data Transmission The transfer of data from one place to another in the form of digital signals is called digital data transmission: A digital signal consists of individual electrical pulses that represent bits grouped together into bytes. Computer accepts and processes data in the form of digital signals. Data is also transmitted from one computer to another through telephone line, microwave system or satellite. In this system, a modem is used on both sides. A modem is an electronic device that can convert the analog signal to digital and vice versa. A digital signal is shown in figure below.
Characteristics of Communication System The communication system depends on• the following characteristics. Delivery - The data must be delivered from source device destination device. Accuracy - The data must be delivered accurately. If there is any error occurred during transmission, the data must be re-transmitted. Timeliness - Data must be delivered within time. It is very important in real time systems because data becomes useless if it is delivered late. For example, in television transmission, the video signals must be delivered within time as they are produced without any significant delay. This kind of delivery is called real-time transmission. Components of Communication System The basic components of a communication system are:
Message - The message. is the information or data that is to be transferred from one location to another. It may consist of text, numbers, pictures, sounds, videos or any combination of these. Sender - A device used in a communication system to send or transmit messages to another device is called Sender, or Transmitter or Source. A sender may be a computer, workstation, telephone handset, video camera and mobile phone. Medium - Medium is a path or channel through which message is transmitted (or sent) from one location to another in a communication system. The twisted wire, fiber optic, microwave, satellite system etc. are used as medium. Receiver - A device used in a communication system to receive messages from another device (sender) is called Receiver or Sink. A receiver may be a computer, workstation, telephone handset, mobile phone, television set, printer, fax machine, and so on. Protocol - A set of rules that guides (or governs) data communication is called protocol. It represents an agreement between the communicating devices. Without a proper protocol, the devices may be connected but they cannot communicate with each other. For example, a person whose mother language is English cannot communicate with a person who can speak only Urdu Note: Today, all type of computers and mobile devices serve as senders and receivers in communication system.
Packets In data communication, data is broken into small group or data segment before being transmitted from one computer to another. These small groups or data segments are called packets. The packet includes the following information: Payload - It is the part of the packet that contains the actual data being sent. Header - It contains the information about the type of data in the payload, the source and destination of data and a sequence number so that data from multiple packets can be re-assembled at the receiving computer in a proper order. See Also or Related Articles:
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