Today, information is spreading so quickly that there is not always enough time to comprehend it. Most people rarely think about how and by what means it is transmitted, and even more so do not imagine the scheme of information transfer.
Basic concepts
The transfer of information is considered to be the physical process of moving data (signs and symbols) in space. From the point of view of information technology, the data transfer process is a pre-planned, technically equipped event for moving information units in a specified time from the so-called source to the receiver through the information channel, or data transmission channel.
Data channel - a set of means or a medium for the dissemination of data. In other words, this is the part of the information transfer scheme that ensures the movement of information from source to recipient, and under certain conditions and vice versa.
There are many classifications of data transmission channels. If we single out the main ones, we can list the following: radio channels, optical, acoustic or wireless, wired.
Technical channels of information transfer
Directly to technical data transmission channels include radio channels, fiber optic channels and cable. The cable can be coaxial or twisted pair. The first are an electric cable with a copper wire inside, and the second are twisted pairs of copper wires, insulated in pairs, located in a dielectric sheath. These cables are quite flexible and easy to use. Fiber optic consists of fiber optic fibers transmitting light signals through reflection.
The main characteristics
of communication channels are bandwidth and noise immunity. By bandwidth, it is customary to understand the amount of information that can be transmitted over the channel for a certain time. A noise immunity is a parameter of the channel resistance to external noise (noise).
Data Transfer Overview
If you do not specify the scope, the general scheme of transmitting information looks simple, includes three components: “source”, “receiver” and “transmission channel”.
Shannon's scheme
Claude Shannon, an American mathematician and engineer, was at the forefront of information theory. He was offered a scheme for transmitting information through technical communication channels.
Understanding this scheme is easy. Especially if you imagine its elements in the form of familiar objects and phenomena. For example, the source of information is a person talking on the phone. The handset will be an encoding device that converts speech or sound waves into electrical signals. In this case, the data transmission channel is
telephone wires, communication centers, in general, the entire telephone network leading from one telephone set to another. The decoding device is the subscriber's handset. It converts an electrical signal back into sound, that is, into speech.
In this diagram of the process of transmitting information, data is presented as a continuous electrical signal. Such a connection is called analog.
Coding concept
Encoding is considered to be the conversion of information sent by a source into a form suitable for transmission over the communication channel used. The most understandable coding example is Morse code. In it, information is converted into a sequence of dots and dashes, that is, short and long signals. The receiving side must decode this sequence.
Modern technologies use digital communication. In it, information is converted (encoded) into binary data, that is, 0 and 1. There is even a binary alphabet. Such a connection is called discrete.
Interference in information channels
Noise is also present in the data transmission circuit. The term "noise" in this case means interference, due to which there is a distortion of the signal and, as a result, its loss. The causes of interference can be various. For example, information channels may be poorly protected from each other. To prevent interference, various technical methods of protection, filters, shielding, etc. are used.
C. Shannon developed and proposed the use of coding theory to combat noise. The idea is that once under the influence of noise there is a loss of information, it means that the transmitted data should be redundant, but at the same time not enough to reduce the transmission speed.
In digital communication channels, information is divided into parts — packets, for each of which a checksum is calculated. This amount is transferred along with each packet. The information receiver recalculates this amount and receives the packet only if it coincides with the original. Otherwise, the packet is sent again. And so on until the checksums sent and received do not match.