Digital transmission system (DTS)

Analyses o the current situation on the project and the development of their technical realization. Brief description of the existing zonal area network. Basic requirements for communication lines. Calculation of the required number of channels.

Рубрика Коммуникации, связь, цифровые приборы и радиоэлектроника
Вид дипломная работа
Язык английский
Дата добавления 20.09.2016

4

Content

Introduction

1. Analyses o the current situation on the project and the development of their technical realization

1.1 Brief description of the existing zonal area network

1.2 Project formulation of the problem

1.3 Basic requirements for communication lines

  • 1.4The lines of communication and the basic properties of the fiber optic link
  • 1.5 Comparison of characteristics and selection of the desired type of optical cable
  • 1.6 The choice of construction method, the route for laying fiber-optic

1.7 Primary BCC Network

  • 1.8 Calculation of the required number of channels
    • 2. The technical part
      • 2.1 Fiber -optic comminication lines

2.1.1 Overview FOL

2.1.2 Structural features FOC

2.1.3 Distribution of light beams in optical fibers

2.1.4 Modes propagating in optical waveguides

2.1.5 Single-mode optical fiber

2.1.6 Constant distribution and phase velocity

2.1.7 Calculation of the main characteristics of the fiber optic link

2.2 Digital transmission systems

2.2.1 The concept of building a modern transmission systems

2.2.2 Transmission systems of PDH, characteristic features

2.2.3 SDH Standard

3. Working documents

3.1 Proposals for the selection of equipment for communication

3.1.1 The main function module SDH networks

3.1.2 Proposal for the selection of the radiation source and photodetector

3.2 Welding questions, and measurement of the optical fiber connection

4. Occupational Health and Safety

4.1 Analysis of dangerous situations

4.2 Creating the optimal working conditions of the operator

4.3 Calculation of illumination LC

4.4 Verification ground settlement

5. Environmental protection

5.1 General

6. Feasibility study of the project

6.1 General

6.2 Investments

6.3 Operating costs

6.4 Operating income

6.5 Gain on sale of services

6.6 Payback period

6.7 Profitability

Conclusion

Application A

Application B

Application C

Bibliography

Introduction

Communication of Kazakhstan to a qualitatively new stage of historical development is determined by the new geopolitical situation. The basis of Kazakhstan's telecommunication is interconnected communication network, ensuring the provision of users of telecommunications services in the country.

Interconnected communications network - the complex conjugate technology telecommunications public networks and private networks with a common centrally managed, regardless of departmental affiliation and forms of ownership.

The first fiber-optic communication line (FOCL) in the CIS countries were built in the early 80-ies of XX century, based on the use of multimode optical fiber, mainly it was the connecting link between the nodes of the СTS network using a 30-channel digital system transmission "Sonata". Although originally mortgaged service life FOCL was not less than 25 years, however, for the stable functioning of the transmission system required to maintain fiber-optic characteristics within acceptable limits.

The first fiber-optic trunks were laid mainly in the city and had a small extent, usually no more than 1-2 km. Inherent cable with multimode fiber mode dispersion of the signal, used for low-speed (2 or 8Mbit / s) transmission systems for short distances was a small amount and is not needed in the measurement. Locating a fault in the trunk of small extent, laid on the cable duct, made by visual inspection.

The situation changed radically with the advent of the 90-ies of XX century for telecommunication systems a single-mode fiber (having less kilometric attenuation and dispersion on the order of magnitude smaller compared to multimode fiber) and high-power laser sources. The length of the fiber-optic sections without of regeneration increased to tens of hundred kilometers, digital signal transmission rate, realized in the emerging systems of transmission of synchronous digital hierarchy (the SDH), reached 622Mbit / s (STM-4 level) and above. Also changed the concept of the construction of communication networks, have become the basic ring and mixed (ring + linear) topology, giving new opportunities to create backup routes of transmission of telecommunications traffic.

In Kazakhstan, the start of construction of the first fiber-optic lines with single-mode type optical fiber in the second half '90s, it was the main line of long-distance communication.

Digital transmission systems (DTS) are characterized by excellent information from analog systems properties. The main advantages of these systems are the following: a higher noise immunity, which can significantly alleviate the requirements for signal propagation conditions on the transmission line; be integrated messaging and switching systems; negligible impact of the transmission line parameters on the channel characteristics; the possibility of using modern technology in hardware DTS; the absence of the phenomenon of accumulation of noise and distortion along the transmission line; a simple terminal equipment as compared to equipment of transmission systems with frequency division multiplexing (FDM); ease of classification of information transmitted.

In this thesis the issues of modernization of the site zonal networks Stepnogorsk-KOCshetau based fiber-optic line. Operated on site equipment K-60 with a transmission medium (electrical cable) does not meet the requirements for the quantity and quality of channels.

1. Analyses of the current situation on the project and the development of their technical realization

1.1 Brief description of the existing zonal area network

On the considered one symmetrical lead-polyethylene cable 1x4x1,2 Stepnogorsk KOCshetau-laid plot, on which the work of analog transmission systems K-60P providing organization 60 channels. Here are the specifications and block diagram of channeling equipment K-60 (Figure 1.1).

Cable1

Cable2

PTS-DS-60-hour dial tone and differential systems; STS-60-hour personal drive; EGR-hour group transformations; SLUK OP-hour linear amplifiers and equalizers; EASB-1-5-hour standardized generator equipment; BCSS-11-hour lead-switching equipment; SDP remote power rack; STS-7 intercom rack

Figure 1.1 Block diagram of a terminal station OC-60P

The transmission system of K-60P is designed for organizations sixty voice channels on the chains of the ISS and ICD symmetrical cables. In rail transport, it is widely used for working on cables INC. The communication system of two-strip cable, line spectrum frequencies is 12-252 kHz. Transmission distance of 12,500 km. The maximum length of re-receiving site on tonal frequency is 2500 km. To ensure such a range in the chain include supervised and unattended repeaters.

Nominal relative transmission rate in line without pre-distortion on all channels is -5 dB, the upper channel pre-distortion -1 dB, -11 dB on the bottom. To maintain the residual attenuation in the terminal equipment and intermediate stations DC has the automatic gain control AGC. The operation of the automatic gain control unit controls the current control frequency: 16 kHz - inclined, 112 kHz - the curved, 248 kHz - flat. At the terminal stations and the PMU-3 uses three-frequency (plane-inclined curved); GMS-2 - dual frequency (flat-sloping) AGC; on NUP - frequency-dependent groundwater AGC.

The greatest gain amplifier stations on the highest frequency to indulge in OP and the PMO is 61 dB, for NFA - 55 dB. Maintenance-free reinforcement points are placed along the highway after an average of 19 km, the PMU-2 - by 250-300 km, PMO-3 - through 500-600 km.

Terminal and served by amplifying points have local sources of supply, NFA are powered remotely from the PMO or OP.

The largest number of NFA between PMO (OP) in the organization of the remote power supply for wire-to-ground system is 12, according to wire-wire system - 6.

Additional information K-60 and the scheme of frequency conversion transmission system K-60P (Figure 1) are given at the end of the explanatory note [A.A.].

On the entire length of the communication line 5 established unattended amplifying points (UAP). Cable laid along the highway Stepnogorsk- KOCshetau (Figure 2) [A.A].

Remote power organized under the "wire-wire", the power of 3 UAP - s made from KOCshetau remaining powered from the village. Stepnogorsk.

On the existing cable line and the precinct organized backbone intercom, as there is a telecontrol system-monitoring equipment.

The aging (about more than 20 years) and by external atmospheric influences polyethylene coating was porous, moisture-permeable, due to which cable parameters changed. Insulation does not meet the required standards, the integrity of the screen is brOCen, resulting in a deteriorated immunity, there were mutual influences and external influences. All this leads to deterioration of communication quality, and, as a consequence of consumer complaints.

On the entire length of the route, except clutches made in the construction of a cable line, a large number of joints resulting from mechanical damage to the cable.

All this leads to greater operating costs for repair and maintenance of existing communication lines, which mainly consist of transport costs and the costs associated with the acquisition of cable necessary to eliminate the frequent injuries, and attempts to bring the cable parameters to the required standards.

Operated transmission system K-60P taken out of production, and it is not available spare parts which are necessary for the replacement of the building blocks. As a result, we have to buy spare parts with similar dismantled, but serviceable systems. The aging and drying installation elements increases defectiveness equipment, resulting in deterioration of reliability.

In addition, the analog channels are used with limited range (0,3-3,4 kHz) and the presence of interference can not provide a large transmission rate required at this stage, for data transmission.

1.2 Project Formulation of the problem

As mentioned above (Section 1.1), there was a strong need for communication channels in this area, that is, to increase the bandwidth capacity of the link. In addition, one should also note that the quality of communication in this area is poor.

Therefore, in this project it is necessary to develop the following issues: selection of the route for laying fiber-optic; definition of requirements in communication channels at a projected fiber optic; choice of optical fiber and cable brands; calculation of the dispersion properties of the fiber and definition of the actual dispersion and attenuation in the line, the calculation of these data regenerator section length; offer a variety of communications equipment, with the necessary factors; Analysis of factors affecting the safety of the personnel working in the construction and operation of communication lines, as well as on the protection of the environment; determine the economic parameters of the project.

1.3 Basic requirements for communication lines

In general, the requirements of a highly modern technology to the telecommunications long-distance communication lines, may be summarized as follows:

- Implementation of communication at distances up to 12,500 km within the country and up to 25,000 ** for international communication;

- Broadband and suitability for the transmission of various types of modern media (television, telephony, data transmission, broadcasting, transmission and front pages of newspapers, etc., as well as modern, interactive forms of communication..);

- Protection of circuits against mutual and external interference, as well as storms and corrosion (electrical cables and optical fiber cables with metal elements);

- The stability of the electrical parameters of the line (electric cables), optical parameters (optical cables), the stability and reliability of the communication;

- Cost communication system as a whole.

Cable lines (electrical and optical) DLD is a complex technical structure, consisting of a large number of elements. Since the line is designed for continuous operation (tens of years and above) and her smooth operation of hundreds and thousands of channels should be provided (thread) connections, then all elements of linear-cable equipment, and first of all the cables and cable accessories included into a linear signal path, high demands. Selecting the type and design of the link is determined by not only the process of propagation of energy along the line, but also the need to protect the adjacent RF circuit from mutual interferences (electrical cable). Cable dielectrics are selected on the basis of the requirements to ensure maximum communication range in the HF channels with minimal losses.

In accordance with this cable machinery developed in the following areas:

1) Development of coaxial systems to organize the powerful beams of communication and transmission on single-cable connection system, cable television programs.

2) Development and implementation of advanced communication OC for a high number of channels and does not require for its production of scarce metals (copper, lead).

3) The widespread introduction in the cable equipment of plastics (polyethylene, polystyrene, polypropylene, etc.), Have good electrical and mechanical characteristics and to automate production.

4) The introduction of aluminum, steel and plastic casings instead of lead. Skins should have the integrity and ensure the stability of the electrical parameters of the cable over the entire service life.

5) The development and introduction of cost-effective designs intra communication cables.

6) Creating a shielded cable, securely protecting transmitted information on them from external electromagnetic influences and thunderstorms, in particular cables in double membranes.

7) Increase of dielectric strength of cables of communication. Modern cable (electrical and optical cable with metal elements) should have the same time as the high-frequency properties of the cable, and the power of an electric cable, and capable of transmitting high-voltage currents for remote unattended power regeneration (amplifier) items over long distances.

1.4 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

10

В-12

Symmetrical cable

106

100

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.

1.5 Comparison of characteristics and selection of the desired type of optical cable

Optical communication cables perform essentially the same function as conventional cables.

In accordance with the adopted in most countries of the structure of construction of communication network, appointment, conditions of use and placement of the OC are divided into trunk, zonal and vnutriobektnye.

Since the OC less durable than traditional cables, they must be protected from the harmful effects of the environment and human activities. These effects include: mechanical stress - tension, bending, compression, torsion, shock; changes in temperature, the penetration of water, prolonged exposure to mineral oil and fire, rodents. The specific design provides protection against these effects by selecting the appropriate cable designs and measures for additional protection.

Conditions for the existence of cables to the trunk, internal, local, facility (LAN) communication networks are different, and the design can be used pretty much different from each other in design, not only the core but membranes and integument. So, OC backbone can be laid directly in the ground, in cable ducts, sewers, tunnels, in the aquatic environment (rivers, lakes, sea), in the air. Most of the cables intrazonal and local networks are in similar circumstances. The much lighter work OC under site-networks, mostly laid before the premises [17].

OC zonal serve to organize multi-channel communication between the regional center and districts with communication range up to 250. Gradient used 50/125 fiber sizes. Wavelength 1.3 ... 1.5 [9].

When choosing a cable design should take into account that the zonal cables are designed with a shaped core.

Zonal cables are used to connect the regional center with the districts and towns of the region. The communication range is usually within a hundred kilometers.

They are made as optical cables zonal communication in which remote power circuit separated from the armor wires and aluminum screen located inside the cable. The cable may comprise 4, 8 or more fibers [9].

Currently, domestic (Russian) cable industry has mastered proiz¬vodstvo optic cables of virtually all types and purposes. These cables meet the requirements of international standards and are made of fibers optiche¬skih foreign proizvodstva.Vse used OB meet the standards of the ITU-T (ITU-T) G.651-G.654. For making OC applied as otechest-governmental as well as imported materials of high quality. Optical fibers po¬stavlyayutsya following well-known companies - Corning Incorporation (USA), OFC - Optical Fiber Solution (formerly a division of LUCENT TECHNOLOGIES, owned by Furukawa now located in the United States), Fujikura (Japan), Alcatel (France), which produces optical fibers type TeraLight, Sumitomo (Japan).

In our country, only just adjusted the production of the cable (optical) products and is mainly used for telecommunication purposes cables foreign and Russian manufacturers. Characteristics of foreign manufacturers of cables are given in the form of a table (Table 1) [PA].

This project proposes to use cable products in Russia.

On the basis of the above fibers (. ITU-T standard (ITU-T) G.651-G.654), fiber optic cables in Russia produce fourteen enterprises [23]:

- JV "Svyazstroy FFS-1," Fiber Optic Cable Company (VOCK), co-founder of OFC (USA), Voronezh;

- JV "Moskabel-Fujikura" (IFC), the co-founder of Fujikura (Japan);

- JV "Samara Optical Cable Company" (JPAC), Samara, co-founder of Corning Inc. (USA);

- CJSC "OCS01" St. Petersburg;

- LLC "Opten" St. Petersburg;

- CJSC "Saranskkabel-Optics", Saransk,

- JSC "Sovkabel-Optics", St. Petersburg;

- Ltd. "Elix-Cable", Moscow;

- CJSC "Yauza cable", Moscow;

- LLC "Eurocable", Moscow;

- CJSC "TRANSVOC" Borovsk, the Kaluga region;

- JSC NF "Wiring harness", Moscow;

- Company VNIIKP-OPTIC, Moscow.

One of the largest Russian companies producing optical cables, is a national firm AONF "Wiring harness". This plant produces almost all types of fiber optic cables for terrestrial PLAYBACK - from the trunk and hanging up intrabuilding OC, and OC to vnutristoechnyh compounds. Figure 1.2 shows a cross section of several types of main OC.

Figure 1.2 Optic trunk cables manufactured by JSC NF "Wiring harness"

Cables type OCBS-T (Figure 1.2) are intended for laying in grounds of all categories, including rodent infected (except soils subject to low temperature deformations), in water for installation over river crossings and navigable rivers deeper than two meters in cable ducts , tubes, blocks, collectors, on bridges and in cable shafts. This type is OC on the outside is covered with a polyethylene membrane, which has a steel wire armor, and under it - the armor of corrugated steel tape.

Figure 1.2 b shows a section OC OCB-M ... OCNB M types. This type of cable has the same purpose. As the power element it uses steel wire or fiberglass rod (center). The outer cable sheath is made of conventional polyethylene or polyethylene, flame retardant. Under the shell there is a steel wire armor.

Cable type OCB-T, shown in Figure 1.2 and has an outer shell made of polyethylene, which is located under the steel wire armor. All of these types are based on OC singlemode OB damped 0.22 dB / km at a wavelength of 1550 nm. their main characteristics are incorporated in the names of the cables:

OCSBS 6,0-10-0,22-8-T - is an optical cable, steel wire armor, the diameter of the central tube (6.0), the core diameter RH (10), the damping RH - 0.22 dB / km, 8 - the number of fibers. Other design parameters OC trunk shown in Table 1.3.

Table 1.3 Constructive parameters of main production OC NF ZAO "Wiring harness"

Structural parameter

Cable type

OKBST

6,0- 10-0,22-8

OKB-M,

OKNB-M

OKBT

-6,0- 10-0,22-8

1.3 Table continuation

-3,0; 4,0; 6,0

3,0; 4,0; 6,0

The diameter of the central tube, mm

-

Number of fibers

4... 24

4... 48

4... 24

Fiber Type

Single-mode or multimode

Single-mode or multimode

Single-mode or multimode

Number of modules

-

6,8

-

Module diameter, mm

-

2,0

-

Central strength member

Steel wire or fiberglass rod

--

The tractive force, H

10000

10000

7000

Operating Temperature, ° C

-40...+50

-40...+50

-40... +50

As the most suitable and satisfying the requirements of graduate design, choose the brand cable OCBST 6,0-10-0,22-8.

1.6 The choice of construction method, the route for laying fiber-optic

In Russia (and CIS), including Kazakhstan, the following options for laying fiber optic link:

- Laying in wOC primer in protective polyethylene pipes (I);

- Laying FOC in protective plastic conduits and symmetrical copper cable to solve the distillation, interoffice communication and signaling circuits in liquidation communication overhead line (II);

- Suspension FOC transmission line supports up to 10 kV, and supports high-voltage lines of automatic block system (III);

- Suspension FOC on the contact rail network supports (IV). Below is a table that compares key indicators.

The following table 1.4 compared methods of laying OC on the basic parameters.

Table 1.4-A comparison of methods for laying OC key indicators

Variants

Main factors

The cost of material resources

Reliability

Speed of construction

Repairability

Durability

Operating costs

The ability to replace the cable at reconstruction

Workability

A place

1

2

3

4

5

6

7

8

9

10

I

1

1

3

1

1

1

+

1

I

II

4

1

4

1

1

1

+

1

II

III

3

4

2

3

4

4

+

3

III

IV

2

3

1

2

3

2

+

2

IV

The method directly into the ground along the railways and roads unprotected against mechanical damage and rodents. However, the method is facilitated by direct burial cable service link. In addition, reduced capital and operating costs. The service life of 20-25 years.

A method of laying cable in the ground in a plastic pipe protects against mechanical damage and rodents. The service life of fiber-optic cable in this case is 40-45 years. Capital and operating costs are greater than the method for directly into the ground.

If the suspension on catenary poles electrified railways, as well as supports high-line power companies will need to pay for their rent and electricity grids corresponding fee optic cable embedded in the ground wire is more expensive than conventional optical cable. This increases the capital costs and operating costs. Term of suspension cable service is 12-15 years, and difficult maintenance of cable lines.

Of the above methods choose II method of laying cable in the ground in a plastic pipe along the road, as in this case, easier maintenance of the cable lines and repair compared with overhead cables, protected from mechanical damage and rodents lifetime longer than that of both methods . This provided access roads maintenance personnel to places of cable laying and the CHP, and in case of damage to the surgical removal of a fault on the line.

The presence of settlements in the path of the track makes it possible to accommodate unserved regeneration areas and the use of existing facilities available telecommunications nodes, which significantly reduces the amount of construction work, and helps to reduce the cost of construction of the road in general.

Depth of the underground installation of optical as well as electrical and 1.2 m. Cable water crossings can be performed by laying under water, on the bridge or by the suspension on the supports. The most reliable is the laying of submarine.

To develop the plan of construction and financial estimates specify the path of receipt of goods for construction, the possibility of using the existing warehouses and handling areas, the deployment of new sites and warehouses, distance methods of delivery of materials to the warehouses, the prices of local materials, etc.

Referring to the map area (Figure 1) we see that the only viable option is obvious route. This option cabling along the highway connecting the city of Stepnogorsk - KOCshetau. [PA].

The total line length is 251 km, the length of the areas: Stepnogorsk - Makinsk - 141 km; Makinsk - KOCshetau - 110 km.

Railway track laid at a distance of 30-60 meters (depending on the specific local conditions) from road axis.

In Akmola region is dominated by flat terrain, it allows you to lay the cable in the main mechanized way. In more detail the organization of railway crossings, as well as mechanized methods cabling discussed in the relevant chapter of the diploma project.

1.7 Primary BCC network

To construct a communication network are required so-called transmission system, ie apparatus through which connection lines for creating channels and group paths. And then arrange of lines and nodes and terminal stations, primary and secondary telecommunications network.

Primary networks consist only of lines, regeneration (amplification) and channeling equipment at the stations. Secondary network comprise further switching nodes allowing to switch communication channels to multiple destinations. But already on the basis of secondary networks are numerous communication services, providing a variety of services. Communication lines laid between the cities and in the major cities, intermediate regeneration (amplifier) ??Items endpoints - all primary network, serving for standard analog and digital channels and paths.

Primary BCC network (interconnected network) is divided into the trunk, zonal and local area network (Figure 1.2).

Figure 1.2 - Backbone, zonal and local primary network

Typical telecommunication channels have the same characteristics, regardless of at what portion of the primary network are formed: these characteristics are strictly standardized and accurately performed. Standardized telecommunication channels a lot, but we are referring only two: the analog channel voice frequency (VF channel) with a bandwidth of 0,3-3,4 kHz and the main digital channel, the bandwidth is 64 kbit / s. Along the lines of the primary network connection is formed such channels. You can create and broadband analog channels, digital channels and with greater bandwidth, but the vast majority of available channels is as follows.

the secondary network is organized on the basis of the above-mentioned basic channels: telephone, telegraph, data transmission, faxes. The number of telecommunication services is growing right before our eyes, and now their number was thirty. To name just a few: city, intercity and international telephone, telegraph subscriber (so-called "TTY"), telex, teletex, telefax, bureaufax, videotex, etc.

Of course, the biggest secondary network and the most numerous services - telephone. Most of the PM and digital channels in the country (it is necessary to think and abroad) are used for the formation of telephone networks. Moreover, often thought (evidenced by many publications) that the telephone network - the only secondary network, the other is not there. In fact this is not true: there are telegraph network - work on them telex (subscriber telegraph) and telegraph service in all offices. Any data transmission network, and not only with the rate of 64 kbit / s, but higher speed, e.g. 2048 kbit / s (E1 channel).

1.8 Calculation of the required number of channels

This trail is part of the zone network, so the calculation takes into account the number of regional and district centers of population. Population in any regional center and the region as a whole can be determined based on census statistics. According to these data, the population of the city of KOCshetau for 2007-2008 amounted to 132.4 thousand people, and in Stepnogorsk -. 46.7 thousand people.. Population growth, taking into account is determined by the formula:

(1.1)

where H0 - population during the census thousand;. P - the average annual population growth in the area (taken as equal to 2-3%); T - period, defined as the difference between the designated year prospective design and the year of the census.

Year prospective design was adopted for 5-10 years ahead. This year the project planning stage to take 10 years to come. In accordance with this parameter T is determined by the formula:

T = 10 for + (Tm-T0), (1.2)

where Tm - year drafting; T0 - the year to which the data H0;

The average annual population increase in Akmola region accept equal to 3% (according to the statistics department). Using formula (1.2) define the parameter T:

T = 10 + (2016-2009) = 7, s

The population in the city of Stepnogorsk, according to (1.1) will be:

, thous. people

The population in the city of KOCshetau will be:

, thous. people

Considering that the telephone lines interurban and international communication are prevail, you must first determine the number of voice channels between specified localities. To do this, use the following formula:

NTF=LKTy (1.3)

where: L and Я - constant coefficients corresponding to the predetermined fixed availability losses, loss usually assumed equal to 5%, while L = 1,3, and = 5,6; KT - gravitation factor; y - specific load, that is, the average load of the one person, y = 0,08 Earl; ma, mb - the number of subscribers served by AMTS terminals, respectively, in points A and B.

The relationship between the selected terminal and intermediate points is determined on the basis of statistical data from enterprises due for the preceding design years. In practice, this relationship is expressed in terms of gravitation coefficient KT, which, studies show, it varies widely, from 0.1 to 12%. The project gravitation coefficient KT is assumed equal to 10%, ie KT = 0,1.

In the future, the number of subscribers served by AMTS terminal, determined according to the population living in the service area. Taking the average coefficient of equipment of public telephones in KOCshetau equal to 0.8, in Stepnogorsk - 0.2 subscribers in AMTS zone can be determined by the formulas:

ma1=0,8HТ1, (1.4)

mb2=0,2HТ2, (1.5)

Inserting data into the formula (1.4) and (1.5) define the number of subscribers served endpoints AMTS:

ma1 = 0,8188,77 = 151,016, thousand. people

mв2 = 0,266,583 = 13,3166, thousand. people

Using formula (1.3) determine the number of voice channels:

nТФ=1,30,10,08+ 5,6 = 133, channels

In the cable transmission line isolated channels and other types of communications: data wire, radio, etc., also take into account the transit channels. In this case, the number of transit links will not be taken into account, they will be taken into account when choosing a transmission system.

Since the number of channels for communication for various purposes can be expressed by the number of voice channels, i.e. VF channels, it is advisable to the total number of channels between the points expressed by the PM channels.

Generally, the total number of channels is calculated according to the simplified formula:

n = 2nТF, (1.6)

n = 1332 = 266, channel

This calculation was made without taking into account the number of backhaul. So if you take into account the transit flows as well as prospects for further development of the network and the possibility of damage which may be necessary to bypass the organization through this highway, then the projected line required transmission speed is 155 Mbit / s (1890 channels).

As the transmission system I suggest using SDH equipment operating over a fiber-optic cable.

The planned establishment of a communication scheme is shown in Figure 3 [PA].

The diagram also shows the required number of PCM streams to be allocated in the corresponding paragraphs.

2. The technical part

2.1 Fiber-optic communication lines

2.1.1 Overview FOL

In fiber optic transmission systems (FOTS) information is transmitted by electromagnetic waves of high frequency, approximately 200 THz, which corresponds to the near infrared range of the optical spectrum of 1500 nm. Waveguides, transferring the information signals to the FOTS is an optical fiber (s) that has the important ability to transmit light at long distances with low losses. Losses in the OB quantitatively characterized by attenuation. Speed ??and distance data transmission are defined distortion of optical signals due to dispersion and attenuation. Fiber-optic network - is an information network that links between the nodes which are fiber-optic communication lines. Technology of optical fiber networks in addition to the issues of fiber optics also cover issues relating to the electronic transmission equipment and its standardization, communication protocols, network topology issues and general issues of networking.

Optical fiber is now considered the most advanced physical medium for the transmission of information, as well as the most promising medium for transmission of large data flows over long distances. The grounds to think so derived from a number of features inherent in optical waveguides:

- Broadband optical signals due to the extremely high carrier frequency Hz. This means that the optical link can transmit information at a bit rate of the order / s (1Tbit / s). In other words, a single fiber can transmit 10 million simultaneous phone calls and a million video. The data rate can be increased by transmitting information in two directions, as the light waves can propagate in the same fiber independently. Furthermore, in an optical fiber can propagate light signals of two different polarizations, which allows to double the capacity of an optical link. To date, the limit on the density of information transmitted through the optical fiber is not reached;

- Very small (compared to other fluids) attenuation of the light signal in the optical fiber. The best examples of Russian fibers have attenuation of 0.22 dB / km at a wavelength of 1.55 microns, which allows you to build a link length of up to 100 kilometers without regeneration of signals. For comparison, the best Sumitomo fiber at a wavelength of 1.55 microns has attenuation 0.154 dB / km. In US optical laboratories developed more "transparent", so-called optical fluorozirconate fiber having a theoretical limit of about 0.02 dB / km at a wavelength of 2.5 microns. Laboratory studies have shown that on the basis of these fibers can be created a communication link with regeneration through portions 4600 km at a transmission order of 1 Gbit / s speed;

- OM made of quartz, which is based on silica, widely distributed, and inexpensive material because, unlike copper;

- Optical fibers have a diameter of about 100 microns, that is very compact and lightweight, which makes them promising for use as aviation, instrumentation, in cable technology;

- Since the optical fibers are insulators, therefore, the construction of communications systems is automatically achieved by isolation segments. In the optical system are completely electrically isolated from each other, and many of the problems associated with the earth and lifting capacities, which still occurred when connecting electrical cables, become irrelevant. Applying extra strong plastic for cable factories made self-supporting overhead cables that do not contain metal and thus safe in electrical terms. Such cables can be mounted on the masts of the existing power lines, both separately and integrated in the phase wire, saving significant funds for laying cable across rivers and other obstacles;

- Communications systems based on optical fibers are resistant to electromagnetic interference, and the information is transmitted over optical fibers is protected from unauthorized access. Fiber-optic communication lines can not listen in a non-destructive way. Any impact on the OB can be detected by monitoring (continuous monitoring) line integrity;

- An important property of optical fiber - longevity. Fiber life time, that is, preservation of its properties within certain limits, more than 25 years that allows to lay an optical fiber cable and one time, as needed, to increase channel capacity by replacing receivers and transmitters at a high-speed.

But there are also some disadvantages of fiber optic technology:

- When creating link requires highly active elements which convert electrical signals into light, and a light to electrical signals. To connect with OM transceiver equipment used optical connectors (connectors), which should have low optical losses and a great resource for connection-disconnection. Errors in the manufacture of such link elements must be of the order of a micron, i.e. meet the emission wavelength. Therefore, optical communication lines the production of these components is very expensive;

- Another drawback is that the precision required, and therefore expensive, process equipment for the installation of optical fibers.

Consequently, when an accident (breakage) of the optical cable, the cost of higher recovery than with copper cables.

The advantages of the use of fiber-optic communication lines (FOCL) are so significant that in spite of these shortcomings of the optical fiber, the communication lines are increasingly being used to transmit information.

2.1.2 Structural features FOC

One of the most important components of fiber optic is a fiber-optic cable (FOC). The defining parameters in the production of the FOC are the operating conditions and the capacity of the link.

Under the terms of operation of the cables are divided into: installation, station, zonal, long-distance.

The first two types of cables are designed for installation inside buildings and structures. They are compact, lightweight and usually have a small construction length.

Cables for the last two types are designed for installation in the wells of cable communications in the ground, on poles along the transmission line under water. These cables are protected from external influences and the construction length of over two kilometers.

The above features and requirements determine the design and type of optical cables. Currently, conventionally there are four types of structures OC (arbitrarily because in arrangement of optical fiber and for other purposes, they can be divided into a larger number of types and designs) [14, 15]:

a) concentric layer cable;

b) beam lay cables;

c) cables with the relevant carrier cores;

g) ribbon cables.

Figure 2.1 shows sketches of optical cable cross-sections of different types: type "a" and "b" refer to the classic design, the types of "c" and "d" characteristic of most optical cables.

1 - optical fiber; 2 - modules; 3-plastic tube; 4-power element.

a - concentric layer; b - twist beam; c - a core profile; d - belt

Figure 2.1 - Typical optical cable construction

OC "a" is in the form of coils of optical modules, twisted around the central reinforcing element. Such a construction is effective when the number of the optical modules is not more than 20. Typical concentric layer OC has an outer diameter of 12 mm and 6 to 8 optical modules. The optical module is a polymeric tube with a freely laid fiber in it.

Optical type "b" of the cable is made up of bundles of optical modules, concentric around a central reinforcing core. The beam is a polymeric tube, inside which there are profiled with longitudinal grooves cores. In these grooves the optical fibers are loosely housed. Unlike OС twisting concentric layer, helix in the optical cable module type "b" have the same direction and pitch. This type of cable contains 25-50 modules in standard design - 40. The external diameter is 15 ... 25 mm.

Optical cable type "c" consists of a core, which is a plastic bearing element with helical grooves into which freely without tension, with the primary fibers are laid containment or optical modules with a diameter smaller groove width. Core optical fibers or modules of insulating tape is wound and covered with a sheath. In some designs OC reinforcing core has a circular cross section around which a spiral wound gasket with alternating there between lie freely optical modules. The cables 'in' type typically contains 8-10 fibers. Their outer diameter - 20 mm.

Сore type cables "d" is assembled from individual flat ribbons with parallel at a distance from each other in a few tenths of a millimeter waveguides. Twisted ribbon cable form the core. The reinforcing elements are located in a sheathed OC. Due to the dense packing of the cable of this design can be manufactured with a very small diameter. Thus, cable 144 of the optical fibers has an outer diameter of 12 mm. The small core sizes allow for layout in combination with other elements of the cable

Each of the considered OC types has its own advantages and disadvantages. Their use in each case is dictated by the installation conditions, the operation and the nature of the problem being solved.

To provide high bandwidth communication line produced FOC containing a small number (8) of single mode fiber with low attenuation, and cables for distribution networks may comprise up to 144 filaments as a single-mode and multi-mode, depending on the distances between network segments [12] .

2.1.3 Distribution of light beams in optical fibers

Optical fiber (Figure 2.1) consists of a core, in which the propagation of light waves, and a cover designed, on the one hand, to create the best conditions for reflection at the interface "core - shell", and the other - to reduce the radiation energy in the surrounding space. In order to enhance the strength and thus the reliability of the fiber over the shell, usually superimposed reinforcing protective coating.

Figure 2.1 - General view of the model RH

This design is used in most RH optical cable (OC) as the underlying core is made from optically denser material. Optical fibers are characterized by a core diameter and the cladding and core refractive index profile, i.e. the dependence of the refractive index of the distance from the axis OB (Figure 2.3) [13].

All optical fibers are divided into two main groups: multimode MMF (multi mode fiber) and singlemode SMF (single mode fiber). In multimode OB having a light-carrying core diameter on the order more transmission wavelengths, distributed a number of different types of light rays - mod. Multimode fibers are separated by the profile of the refractive index in the step (step index multi mode fiber) and gradient (graded index multi mode fiber).

The main factors affecting the nature of light propagation in the fiber, along with the emission wavelength, are the geometric parameters of fiber, attenuation, dispersion.

The principle of the propagation of optical radiation along the optical fiber based on the phenomenon of total internal reflection at the interface with

different refractive indices. The propagation of light beams in an optically denser medium surrounded by a less dense shown in Figure 2.2. The angle of total internal reflection, in which the incident on the border of the optically denser and an optically less dense medium is totally reflected light is determined by the relation

(2.1)

where n1 - the refractive index of the core RH; n2 - refractive index of the shell RH, and n1> n2.

Figure 2.2 - Distribution of radiation and by stepwise gradient multimode and singlemode OС

If you get on the end of the light emission RH it can spread three types of light beams, called guides and attendant emitted rays, the existence and prevalence of any type of rays determined by the angle of incidence on the interface between the "core - shell". Those rays which fall on the interface at an angle (rays 1, 2 and 3), and are reflected from it again back into the fiber core, and propagates in it without undergoing refraction. Since the path of the rays is completely located within the propagation medium - core fiber, they are spread over long distances and are called rails.

Rays incident on the interface at an angle (rays 4), are called flowing rays (rays of the shell). Reaching the boundaries of the "core - shell", these rays are reflected and refracted, each time losing sheathed fiber portion of the energy, and therefore disappear completely at some distance from the fiber end. The rays that are emitted from the shell to the surrounding space (5-rays) emitted rays are named and appear in places of irregularities or curling due RH. Radiated and the resulting beams are parasitic and cause dissipation of energy and the distortion of the information signal.

2.1.4 Modes propagating in optical waveguides

In general, the propagation of electromagnetic waves described by the system of Maxwell's equations in differential form:

(2.2)

Where - density of electric charge; and - the electric and magnetic fields, respectively; - Current density; and - the electric and magnetic induction.

If we imagine the electric and magnetic fields, and with the help of the Fourier transform [14]:

(2.3)

The wave equations take the form:

(2.4)




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