INTRODUCTION TO DATA COMMUNICATION

-

DATA COMMUNICATION

Data communication refers to the exchange of data between a source and a receiver via form of transmission media such as a wire cable. Data communication is said to be local if communicating devices are in the same building or a similarly restricted geographical area.

                                                            DATUM mean the facts information statistics or the like derived by calculation or experimentation. The facts and information so gathered are processed in accordance with defined systems of procedure. Data can exist in a variety of forms such as numbers, text, bits and bytes.

A data communication system may collect data from remote locations through data transmission circuits, and then outputs processed results to remote locations.
                    
Components of data communication system :
A Communication system has following components: 
1. Message: It is the information or data to be communicated. It can consist of text, numbers, pictures, sound or video or any combination of these.
2. Sender: It is the device/computer that generates and sends that message.
3. Receiver: It is the device or computer that receives the message. The location of receiver computer is generally different from the sender computer. The distance between sender and receiver depends upon the types of network used in between.
4. 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 wire, coaxial cable, fiber-optic cable 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.

A protocol performs the following functions:
1. Data sequencing. It refers to breaking a long message into smaller packets of fixed size. Data sequencing rules define the method of numbering packets to detect loss or duplication of packets, and to correctly identify packets, which belong to same message.
2. Data routing. Data routing defines the most efficient path between the source and destination.
3. Data formatting. Data formatting rules define which group of bits or characters within packet constitute data, control, addressing, or other information.
4. Flow control. A communication protocol also prevents a fast sender from overwhelming a slow receiver. It ensures resource sharing and protection against traffic congestion by regulating the flow of data on communication lines. 
5. Error control. These rules are designed to detect errors in messages and to ensure transmission of correct messages. The most common method is to retransmit erroneous message block. In such a case, a block having error is discarded by the receiver and is retransmitted by the sender.
6. Precedence and order of transmission. These rules ensure that all the nodes get a chance to use the communication lines and other resources of the network based on the priorities assigned to them.
7. Connection establishment and termination. These rules define how connections are established, maintained and terminated when two nodes of a network want to communicate with each other. 
                       
8. Data security. Providing data security and privacy is also built into most communication software packages. It prevents access of data by unauthorized users.
9. Log information. Several communication software are designed to develop log information, which consists of all jobs and data communications tasks that have taken place. Such information may be used for charging the users of the network based on their usage of the network resources.
The effectiveness depends on four fundamental characteristics of data communications
1. Delivery: The data must be deliver in correct order with correct destination.
2. Accuracy: The data must be deliver accurately. 
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.



Comments

Post a Comment

Popular posts from this blog

Introduction of Digital computer

-
Image
INTRODUCTION Digital computer concept:- 1. Digital computers are designed to store, process and communicate information in digital form. 2. Digital computer is any of a class of digital devices capable of solving problems by processing information in discrete form. 3. It is used for processing data represented by discrete, localized physica signals, as the presence or electic current. 4.The main three components of digital computer:- >input:- The user gives a set of input data through input devices. >Processing :- The input data is processed with the help of CPU by well defined and finite sequence of step. >Output : - Some data available from the processing step are output to the user. TYPE OF DIGITAL COMPUTER :- 1.Microcomputer/Desktop computer 2.Minicomputer 3.Mainframe computer 4.Supercomputers Microcomputer :- 1.Microcomputer is also called a personal computer or desktop computer. 2.It includes a microprocessor, memory, and
Read more

INTRODUCTION OF DBMS

-
What is Database :- The database is a collection of inter-related data which is used to retrieve, insert and delete the data efficiently. It is also used to organize the data in the form of a table, schema, views, and reports, etc. For example: The college Database organizes the data about the admin, staff, students and faculty etc. Using the database, you can easily retrieve, insert, and delete the information. DBMS (Database Management System):- Database management system is a software which is used to manage the database. For example: MySQL, Oracle, etc are a very popular commercial database which is used in different applications.DBMS provides an interface to perform various operations like database creation, storing data in it, updating data, creating a table in the database and a lot more.It provides protection and security to the database. In the case of multiple users, it also maintains data consistency. DBMS allows users the following tasks:- Data Definition: I
Read more

Introduction to cache memory

-
Image
Cache Memory in Computer Organization Cache Memory  is a special very high-speed memory. It is used to speed up and synchronizing with high-speed CPU. Cache memory is costlier than main memory or disk memory but economical than CPU registers. Cache memory is an extremely fast memory type that acts as a buffer between RAM and the CPU. It holds frequently requested data and instructions so that they are immediately available to the CPU when needed. Cache memory is used to reduce the average time to access data from the Main memory. The cache is a smaller and faster memory which stores copies of the data from frequently used main memory locations. There are various different independent caches in a CPU, which stored instruction and data. Levels of memory: Level 1 or Register – It is a type of memory in which data is stored and accepted that are immediately stored in CPU. Most commonly used register is accumulator, Program counter, address register etc. Level 2 or Cac
Read more