The lines of communication and the basic properties of the fiber optic link

At the present stage of development of society in the conditions of scientific and technological progress continually increase the amount of information. As shown by theoretical and experimental (statistical) research, communication industry production, expressed in the amount of transmitted information increases in proportion to the square of the growth of the gross domestic product of the economy. This is determined by the need to expand the relationship between the various links of the national economy, as well as increasing the amount of information in the technical, scientific, political and cultural life of society. Increases the demands on the speed and quality of transmission of a variety of information, increasing the distance between callers. Communication is essential for the operational management of the economy and of public authorities to improve the country's defense and to meet cultural and social needs of the population.

In an era of scientific and technological revolution, communication has become an integral element of the production process. It is used for process control, electronic computers, robots, industrial enterprises t. D. An essential and one of the most complex and expensive coupling elements are link (LAN), which transmits the information electromagnetic signals from one subscriber (station transmitter , regenerator, etc.) to another (the station, the regenerator, and a receiver r. h.) and back. It is obvious that the effectiveness of the communication systems is largely determined by the quality of medicines, their properties and parameters, as well as the dependence of these quantities on the frequency and impact of various factors, including the third-party interferences of electromagnetic fields.

There are two main types of drugs: the line in the atmosphere (radio link RL) and the guide link (link). Below are the main types of opportunities and common rail communication systems (Table 1.1)

Table 1.1 Frequency-classification systems and radio guide

Frequency, Hz	Wavelength	The guide system	Radiofacilities
105	km	AL	RL
106	100 M	SC	RL
108	м	СС SWL	RL
109	дцм	CC SL	RRL
1010	cm	-	RRL
1011	mm	MW DW	-
1012-1014	IRL	**	**
1014-1015	OL	L	-
1015-1017	UVL	**	**

Note: * According to the bands conducted experimental work on the development in the field of telecommunications and radio.

A distinctive feature of the guide lines is that signals propagating therein from one user (station apparatus, the circuit element and the like. D.) To another is carried out only by specially created circuits and paths PM forming guide system for transmitting electromagnetic signals in a predetermined direction due to the quality and reliability.

Currently, communication links are transferred from the DC signals to an optical frequency range and the operating wavelength range extending from 0.85 microns to hundreds of kilometers.

There are three main types of drugs: Cable (TC), air (VL), optical fiber (fiber optic). Cable and overhead lines are wired lines in which the system guides the system image "conductor-insulator", and fiber-optic lines are dielectric waveguides, guiding system consisting of dielectrics with different refractive indices.

Fiber-optic lines are systems for transmitting light signals of the microwave wavelength range from 0.8 to 1.6 microns on optical cables. This type of links is seen as the most promising. The advantages of fiber optic links are low loss, high bandwidth, low weight and compact dimensions, the savings of non-ferrous metals, high degree of protection from external interference and. Below (Table 1.2) shows the comparative characteristics of different guides on the number of channel systems, as well as to the range.

Table 1.2- Number of communication channels for different guide systems

Guiding system	Frequency Hz	Possible number of telephone channels	Transmission system
Air line	105		В-12
Symmetrical cable	106		К-60; К-120 (And a number of joint venture PCM)
Coaxial cable	108	1000-10 000	К-1920 (And a number of joint venture PCM)
The waveguide	1011	100 000	К-3600
The light guide	1014 -1015	100 000 000	К-10800,JV with PDH and SDH **

Note: JV with PDH and SDH ** - transmission system supporting PDH and SDH technology, working on the optical cable.

Conclusion: In view of the major requirements for the communication lines, and comparing the characteristics of the various communication lines (with the main fiber-optic properties) from the land-zone network Stepnogorsk KOCshetau proposed upgrade link based on optical cable.