Data Communication
The term data communication comprises two words : Data and Communication.Data can be any text, image, audio, video and any multimedia files. and the communication is an act of sending and receiving data.
Thus data communication refers to the exchange of the data between two or more networked or connected devices. example of such devices include personal computers, mobile phones, laptops etc.
Data communication refers to the exchange of data between a source and a receiver via form of transmission medium such as wired cable.
The data communication is said to be local if communicating devices are in the same building or a similarly restricted geographical area.
The device that transmits the data is known as source and the device that receives the transmitted data is known as receiver.
Components of data communication
A communication system has following components :-
1. Sender : A sender is a device which is capable of sending data over a network. It can be a computer, mobile phone, laptop, smart watch etc.
2. Receiver : It is a destination where finally message sent by source has arrived. It is a device that receives message same as sender. receiver can also be in form of a computer, telephone, mobile , workstation etc.
3. Message : It is the data or information that needs to be exchanged between the sender and the receiver. Message can be in the form of text, image, audio, video, multimedia files etc.
4. Transmission Medium : It is the channel or physical path through which the message is carried from sender to the receiver. The medium can be wired like twisted pair cable, fiber-optic cable etc. or wireless like laser, radio waves and microwaves.
5. Protocol : It is a set of rules that govern the communication between the devices. Both sender and receiver follow same protocols to communicate with each other.
To govern data communication, various set of rules had been already designed by the designers of the communication system, which represent a kind of agreement between communicating devices. These are defines as protocol.
Example of a data communication system is sending an email. The user which send email act as sender, message is data which user wants to send, receiver is one whom user wants to send a message, there are many protocols involved in this entire process, like SMTP(Simple Mail Transfer Protocol), both sender and receiver must have an internet connection which uses a wireless medium to send and receive email.
Characteristics of Data Communication
The effectiveness depends on four fundamental characteristics of data communication.
1. Delivery : The data must be deliver in correct order with correct destination.
2. Accuracy : The data must be deliver accurately means no change in the content of message sent by the sender during the transmission.
3. Timeliness : The data must be deliver in a timely manner late delivered data useless.
4. Jitter : It is the uneven delay in the packet arrival time that cause uneven quality. Jitter refers to the variation in the packet arrival time.
Example : Let us assume that video packets are sent every 30 m.s If some of the packets arrive with 30 ms and others with 40 ms delay, an uneven quality in the video id result.
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