Banking Computers Science Data Communication and Networking Data Communication

 

Data Communication

 

 

 

Introduction

 

Data communication is the transmission of coded data between remote terminals and a centralized computer installation, or between two or more Computer center over establish communication links.

 

Advantages of Data Communication System

·         Saving of time in data preparation and physical transportation of prepared data.

·         Full utilization of processing power and storage capacity of modern computer.

·         Quick retrieval of information from files.

·         Eliminates duplication of files.

·         Reducing the cost of data transmission.

 

 

 

Type of Transmission Channel

 

There are mainly three types of transmission channel

 

1. Simplex channel:

\[\text{A(Sender)}\xrightarrow[{}]{{}}\text{B(Reciver)}\]

In this channel transmission of data is always in one direction, after receiving the radio signal from radio-station, the receiver can't send back the signal to radio-station. Transmission always flows from A to B.

 

2. Half Duplex channel

\[\text{A(Sender)}\text{B(Reciver)}\]

In this channel transmission of data is in both directions, but at any one Instant of time it is only in one direction. It means there is flow of transmission

From either A to B or from B to A at one time, such as telephone line.

 

3. Full duplex channel

\[\text{A(Sender)}\text{B(Reciver)}\]

In this channel transmission of data is in both directions simultaneously. It means there is flow of transmission from A to B and from B to A at a one instant of time.

 

Parity Check: In communication parity bit is used to check data that has been transmitted accurately. The parity bit is added to every data unit that are transmitted. The parity bit for each unit is set so that all bytes have either an odd number or an even number of number is. Parity bits are used as the simplest form of error detecting code.

 

Information Transfer speed: Information Transfer speed is measured by bit and baud rate. Bit rate indicates the speed of bits transmitted within one second. Baud rate counts the number of times of a transmission change state.

 

Data Communication Channel

Data is terminal from a terminal to a computer system from to a terminal over communication channel which are also Called communication lines or data links. They are of the following types:

 

1.    Standard Telephone Line         

2.    Coaxial Cables

3.    Microwave Transmission  

4.    Satellite Communication

5.    Fiber Optics.   

 

1. Standard Telephone Line: It is widely used as communication channels. It is very effective and useful to the user of data communication because it is easy to join and the complex network of telephone lines has been already established all over the world. It consists of two wires of copper covered with insulator

 

           

2. Coaxial Cable: These are high quality communication lines that have million bits per second. Coaxial cabling is the primary type of cabling used by the cable television industry and is also widely used for computer networks, such as Ethernet. Although it is more expensive than a standard telephone wire, it is much less susceptible to interference and can carry much more data.

 

 

3. Microwave transmission: It transmits signals through open space like radio signal. It provides a much faster transmission rate than telephone line or coaxial cable. In this system data transmits on a line of sight path and needs antenna. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks. It consists of series of relay stations approximately 30 miles apart. For transmitting to long distances, signals are amplified and retransmitted from station to station. It provides higher bandwidth but it is affected by rain, dust, cloud and bad weather. It is

 

 

 

4. Satellite Communication: A Satellite Communication is known for fast from the earth. The satellite amplifies signal received from one earth station and retransmits the signals to another     Ife earth station which can be located many    

Thousands of miles away they are also used for mobile application such as communication to ships vehicle planes hand ?held terminals and for TV and radio broadcasting for which application of other technology such as cable is impractical or impossible.

 

 

5. Fiber Optics: This cable consist of one or more thin filaments of glass fiber wrapped in a protective layer. It is a new technology that may serve to replace conventional wire and cable in communication it is a glass or plastic fiber are widely used length. Optical fibers are widely use in fiber topic communication which permit transmission over longer distances and at higher bandwidths than other forms of communications. It interference. The speed of fiber optics is hundreds of times faster than coaxial cables and thousands of times faster than twisted-pair wire.

 

 

 

Network

 

A computer network is a group of computers that are connected to each other for the purpose of communication. A computer network allows which provide facility of sending and receiving of information between computers or sharing of information between computing devices. To establish any network needs sender, receiver, medium and protocol. ARPANET was the first operational computer network in the world  

 

 

 

Computer Network can be used for several purpose

 

1. Facility Communications: Using a network, people can a network People a communication efficiency and easily view E-mail instant massage chat rooms telephone video telephone calls, and video conferencing.

 

2. Sharing Hardware:  In a network environment each computer on a network can access and use hardware on the network. Suppose several personal computers are on a network and each requires the use of a laser printer. If the personal computers and a laser printer are connected to a network, each user can then access the laser printer on the network, as the authorized user can access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks. As they need it

 

3. Sharing file and Data and Information: in a network environment any authorize user can access data and information and storage other computers on the network the capability of the providing access to data and information on shared storage devices is an important feature of a many Networks.

 

Sharing Software:  Users connected to a network can access application program on the network.

 

 

 

Some Network related terms

 

Protocol: A protocol is a set of rules and standards which is used by computers to exchange information or data with each other across a network. It can be defined as the rules governing the syntax, semantics, and synchronization of communication.

 

Nodes: In a network a node is a connection point where either data transmission end or redistribution of data starts

 

Server: A server is a man computer that manages resource to other computer connected to a network resources store on the server. It is main and powerful computer on network. Any user on the network can access the resource store on the server it is man and powerful computer on network. It is a central computer which holds collection of data and program for PCs, that they perform no other tasks besides their server tasks. A server in this case could refer to the program that is managing resources rather than the computers connected in a network. Server computer needs to be fast and to have a large storage capacity hard disk and lots of RAM at the end of the link from the host processor.

 

Terminal:   In data communication terminal is computer equipment in data the end of the link from the host processer the terminal may be another Computer or a general purpose terminal device such as keyboard, VDU or a special purpose terminal cash registers, banking terminals. A computer terminal is an electronic device that is used for entering data into, and displaying data from a computer. It is used to share the resources of mainframe or supercomputer.

 

Dumb Terminals: Dumb terminals are display and input devices which don't process data and input locally, instead transmitting input to a computer to which it is connected and displaying the resulting output. A dumb terminal refers to a monitor and keyboard that have no processing power of their own. It is simply an input and output device wired into another computer.

 

Networking device

There are devices to establish a network

1.    Repeaters

2.    Hub

3.    Switches

4.    Routers

5.    Gateways

 

 

 

Types of Network

 

There are different types of network

 

1. Local Area Network (LAN): A local area network is a computer network covering a small geographical area, like a home, office, or small group of buildings, such as a school, or an airport. It is small in size but computers connected to a LAN can share information and share peripheral equipment?s at present LAN is based on Ethernet technique network

 

2. Wide Area Network (WAN):  A wide area network is a computer network that covers abroad area such as any network whose communications to connect LANs and other types of networks together, so that users and other locations. WANs are often built using leased lines or switched circuit. Internet, Indonet developed by CMC in India and ATM services of bank are good examples of WAN.

 

3. Metropolitan Area Network (MAN): A Metropolitan Area network is a large computer network that usually spans a city or a large campus. An up-link services to wide area networks and the Internet Routers, switch and hub all together forms a MAN.

 

 

 

Network Topology

 

There are different types of network topology ?

 

1. Mesh Network: Mesh Networking is a type of networking wherein each node in the network may act as an independent router, regardless of whether it is connected to another network or not. It may be used for instances of high traffic conditions to broken or blocked paths by "hopping" from node to node until the destination is reached. A mesh network whose nodes are all connected mesh network is high because of large amount of cable required and each node required intelligence. As a result, the network may typically be very reliable, as there is often more than one path between a source and a destination in the network.

 

 

2. Star Network: Star Network are one of the most common computer network topologies. In as intelligence called hub. Thus hub, other nodes and the transmission lines between them form a graph with the topology of a star. The star topology reduces the chance of network failure by connecting all of the systems to a central node any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected. If the central node fails then the whole system goes fails.

 

 

3. Ring Network: A ring network is a network topology in which each node has equal amount of intelligence. The direction of data flow around the ring usually   one wav. Each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node like ring. Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link. Anode failure or cable break might isolate every node attached to the ring.

 

 

4. Bus Network: A bus network topology is a network in which a set networks are the simplest way to connect multiple nodes, but may have bus. When a node wishes to transmit data to another node it must listen to the bus to see if anyone else is transmitting. If no data is on the bus then it will transmit. The node must be intelligent enough to listen to the bus and recognize their own address in order to receive incoming data.

 

 

 

 

Modulation: Modulation is used to send an information bearing signal over long distances. It usually involves varying one waveform in relation to another waveform. Modulation is a process to change the analog signal to digital signal and digital signal to analog signal. A device that perform these operations is called a modem.

 

There are three types of modulation

 

1. Amplitude Modulation: It is a process to change the amplitude of carrier signal according to digital signal having information.

 

2. Frequency Modulation: It is a process to change the frequency of carrier signal according to digital signal having information according to digital signal having information.

 

3. Phase Modulation: It is a process to change the phase of carrier single according to digit signal having information.

 

Data Transmission Service

The service used to transmit data from one place to another place is called data transmission service and the organization which provide this service is called data transmission service provider.

 

1. VSNL (Videsh Sanchar Nigam Limited)

2. BSNL (Bharat Sanchar Nigam Limited)

3. MTNL (Mahanagar Telephone Nigam Limited)

 

 

 

Varies Data Transmission service

 

1. Dial up lines: Dialup lines are related with telephone connection which are connected to a telephone connection in a system of many lines Shared by many users. It is used by dialing the number like telephone and it is used to already establish telephone lines over the world. Dial-up lines are sometimes called switched lines. Broad band technique is also used by dial up lines.

 

2. Digital subscriber lines (DSL):  DSL is a very high-speed internet connection that uses the same wires as a regular telephone line. The speed is much higher than a regular modem. DSL doesn't necessarily require new wiring; it can use the phone line we already have.

 

3. Leased line: A leased lines connects the two location for voice and data transmission it is also called dedicated lines and it makes transmission possible near and far both. It is not only dedicated line between two points makes sure to provide higher quality bandwidth in network traffic.

 

4. ISDN integrated service digital Network.is used to transmit voice, video, images and data through switched telephone network. Voice, video, images and data are transmitted through this system are noise- free and digital form. There is no need of modem in ISDN because data is transmitted in digital form.

 

Network Interface Card:   A network interface card is a hardware component designed to allow computers to communicate over a computer network or enables our computer to connect to other computers. Computer sends and receives data packets in network under a protocol.

 

Wireless Technology: It is a technology which make possible to send or receive data without cable and saves the cable cost, it uses electromagnetic, microwave and infrared waves etc. at the place of cable. The applications of wireless technology are television remote control. Cellular phone and etc.

 

Wi MAX (Worldwide Interoperability for Microwave Access): It is a wireless transmission of data using a variety of transmission modes. The technology provides up to 10 Mbit / s broadband speed without the need of cables.

 

WLL (Wireless Local Loop): It is another name for fixed wireless. Wireless local loop is a term for the use of a wireless communications link in which a user connects with network through radio frequency. It is popular to that locations where land-line telephone connection is not available. It is based on CDMA (Code Division Multiple Access) technology.