DATA COMMUNICATION AND NETWORKING
With the advancement of Data Communication facilities the communication between computers has increased and thus it has extended the power of computer beyond the computer room. Now a user sitting at a one place can communicate with computers on any remote site through communication channel. In this post you can understand about Communication Protocols and Data Transmission modes.
In Data Communication Four basic terms are frequently used
- DATA : A collection of facts in raw forms that become information after processing.
- SIGNALS : Electric or Electomagnetic encoding of Data.
- SIGNALING : Propagation of signals across a communication medium.
- TRANSMISSION : Communication of Data achieved by the processing of signals.
COMMUNICATION PROTOCOLS
Data communication software It is software that enables us to communicate with other systems. The Data communication software instructs computer systems and devices as to how exactly data is to be transferred from one place to another. The procedure of data transformation in the form of software is commonly known as protocol.
The Data transmission software or protocols perform the following functions for the efficient and error free transmission of data.
- Data Sequencing : A long message to be transmitted is broken into smaller packets of fixed size for error free data transmission.
- Data Routing : It is the process of finding the most efficient route between source and destination before sending the data.
- Flow Control : All machines are not equally efficient in terms of speed. Hence the flow control regulates the process of sending data between fast sender and slow receiver.
- Error Control : Error detecting and recovering is the one of the main functions of communication software. It ensures that data are transmitted without any error.
DATA TRANSMISSION MODES
- Simplex : In simplex mode the communication can take place in one direction. The receiver receives the signal from the transmitting device. In this mode the flow of information is Uni-directional. Hence it is rarely used for data communication. Example Mouse, Keyboard.
- Half Duplex : In Half duplex mode the communication channel is used in both directions, but only in one direction at a time. Thus a half duplex line can alternately send and receive data. Example Army phones (Walky Talky).
- Full Duplex : In full duplex the communication channel is used in both directions at the same time. Use of full duplex line improves the efficiency as the line turnaround time required in half duplex arrangement is eliminated. Example Telephone line.
COMMUNICATION MEDIA
These are the major communication devices which are frequently used :
Wire Pairs.
Wire pairs are commonly used in local telephone communication and for short distances digital data communication. They are usually made up of copper and the pair of wires is twisted together. Data transmission speed is normally 9600 bits per second in a distance of 100 meter.
Coaxial Cables
Coaxial cable is group of specially wrapped and insulated wires that are able to transfer data at higher rate. They consist of a central copper wire surrounded by an insulation over which copper mesh is placed. They are used for long distance telephone lines and local area network for their noise immunity and faster data transfer.
Microwave
Microwave systems uses very high frequency radio signals to transmit data through space. The transmitter and receiver of a microwave system should be in line of sight because the radio signal cannot bend. With microwave very long distance transmission is not possible. In order to overcome the problems of line of sight and power amplification of weak signal, repeaters are used at intervals of 25 to 30 kilometers between the transmitting and receiving end.
Communication Satellite
The problem of line sight and repeaters are overcome by using satellites which are the most widely used data transmission media in modern days. A communication satellite is a microwave relay station placed in outer space. INSAT-1B is such a satellite that can be accessible from anywhere in India. In satellite communication, microwave signal is transmitted from transmitter on earth to the satellite at space. The satellite amplifies the weak signal and transmits it back to be receiver.The main advantage of satellite communication is that it is a singe microwave relay station visible from any point of a very large area. In microwave the data transmission rate is 16 giga bits per second. They ahttps://unwantedcarremovalsydney.com.au/re mostly used to link big metropolitan countries.
TOPOLOGY
The geometric arrangement of a computer system. Common topologies include Bus, Star, Ring...
If you want to know more about Network topologies then click on this link..
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