Brief description of the existing zonal area network
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.
Analyses of the current situation on the project and the development of their technical realization
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).
| EASB 1-5 |
| PTS-DS 60 |
| STS-60 |
| EGR |
| SLUK OP |
| BCSS 11 |
| SDP |
| STS-7 ТУ ТМ |
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.