Design of Fiber Optic Transmission Line

Contents

CONTENTS

INTRODUCTION

1 ROUTE SELECTION

2 OPTICAL CABLE CHARACTERISTIC

3 CHARACTERISTICS OF TRANSMISSION SYSTEM

4 LOCATING AND CALCULATING REGENERATION SITE ATTENUATION

5 CALCULATION OF SINGLE MODE OPTICAL FIBRE PARAMETERS

6 CALCULATION OF UXO EARTHING

7 CONSTRUCTION OF FIBER OPTIC TRANSMISSION LINE

CONCLUSION

ROUTE SITUATION PLAN

CABLE CROSS SECTION

Introduction

The intensive development of DSPs is due to their significant advantages over analog transmission systems. They have high noise immunity, stability of channel parameters, independence of transmission quality from the length of the communication line, efficiency of using channel capacity for transmitting discrete signals, simpler mathematical processing of transmitted signals.

The growth of traffic over fibre-optic communication networks presents operators with the task of combining primary signals at a rate of 2048 kbit/s (E1) into high-speed digital flows that can be used by operators to build modern high-capacity digital networks and provide access to trunk links. The multicast flow rate is 68376 kbps.

The goal of this course project is to develop a communication line between the settlements of Mogilev - Krasnopolye, involves providing consumers with high-speed Internet, digital television and other modern services presented on the Belarusian market. This will be achieved through the laying of fiber optic transmission lines and the use of digital transmission systems, taking into account the further development of communication networks in this area.

7 construction of fiber optic transmission line

Preparatory work.

Cable of one manufacturer is laid in the area between NRP points. We perform visual inspection of the reels and ends of the HO cable. If there are no damages, it is necessary to:

- fiber integrity;

- measurement of attenuation;

- test of electrical strength of strands insulation and measurement of electrical resistance of hose cover;

- determination of integrity of optical fibres and attenuation is performed by connecting end.

We compare the results in accordance with the attached passport. In case of noticeable discrepancies of these characteristics with those specified in the certificate, measurements are carried out from two ends of the cable, after which these ends are sealed.

The construction length cannot be accepted for laying and installation, if during the inspection significant damage to the drum is found, measurements in this case are not carried out. As a result of the measurements, a fiber break or an excess of attenuation established by the certificate was detected taking into account the permissible spread of parameters for this cable.

To obtain maximum homogeneity of VOLS characteristics, cable construction lengths are grouped according to design data and dimensions of construction lengths.

A laying list shall be drawn up indicating the drum number, cable grade, manufacturer's factory (firm), length of cable on the drum, attenuation of construction length, date and number of the report, test of construction length of the cable site.

Cable laying:

- cable laying device (not less than 1.2 m) for soil of group 1-4, regardless of cable type and its purpose;

- pit 2,000 x 1,000 x 1,300 (mm) is opened at the end of one construction length and beginning of the other;

- the end laid on the cable is released from the cassette and the remaining length is not less than 15 m. On the other side of the pit, the cassette is charged to the end of the cable of the next construction length, leaving the same length (15 m).

Water barriers.

Throughout the length of the route, 6 rivers will have to pass. Of these, 5 rivers are a depth of up to 0.8 meters with gentle banks and with a dense, not viscous bottom. Through such rivers we will lay cable as well as along the entire length of the route using a cable laying device and without any additional mechanisms. However, there is a deeper river up to 6 meters deep. A cable will be laid across such a river along a road bridge. Since there are troughs from the side of the bridge, the cable will be laid in them in accordance with the rules for pulling the cable into the cable sewer .

Lay the cable manually.

In the settlements of Smolka, Volkovichi, Lopatichi, Novaya Sloboda and Sidorovka there is no cable sewer and in cramped places the cable will be laid using a trench and labor. In the village of Smolka, cable laying along the street along the houses will take place using a trench. In Volkovichi, along the territory of the VSZN plant, you will have to dig a trench by hand with a length of 100 meters. In the settlements of Lopatichi and Novaya Sloboda, we will also use a trench to pass streets with residential buildings. In the village of Sidorovka near the store "Pogrebok" you will have to develop a trench manually.

Laying the cable into the cable sewer.

In the village of Slavgorod, the cable will be laid into the cable sewer according to the following principle:

Before the cable laying works, preparatory works are carried out, consisting in cleaning the cable wells from water and dirt, ventilation for cleaning them from luminous and swamp gases, which can accumulate in the wells, as well as in preparing the sewage channel for cable pulling.

The steel cable to which the cable is attached is inserted into the channel by means of a thin cable, rope or capron cord, the passage of which into the pipe channel is commonly called a channel blank. The blank can be made by means of various devices.

To attach the cable to the cable, a steel stockade is worn at its end. When pulled, the stockings decrease in diameter and tightly enclose the cable.

The cable can be pulled by means of a motor or manual winch installed at the manhole of the well. To prevent damage to the cable shell against the edge of the channel, a safety plug is inserted into the pipe hole or a special guide template (elbow) is used. To reduce friction between the walls of the channel and the cable, the latter is abundantly lubricated with technical vaseline before entering the channel.

The gasket will be made into a free channel of polyethylene pipe.

Crossings over highways.

In order not to stop traffic during the construction of the cable line, at the intersection of the route with highways, cables are usually laid in pipes previously laid under the roadway. Laying of plastic pipes, we will perform by horizontal drilling of soil. We're gonna need to lay 1 pipe. The pipe ends shall extend not less than 1 m from the ditch edge and lie at a depth of not less than 0.8 m from its bottom.

Drilling of Soil and tightening of pipes is performed by hydraulic drill. The drilling process is as follows. With the help of hydraulic cylinder block and high-pressure pump, steel rod is pushed into the ground, consisting of sections with length of 1 m, screwed onto each other as they are pushed. After reaching the opposite side of the highway of the end of the first rod with a screwed tip, the latter is replaced by an expander, which is extended in the opposite direction; Note here that channel is formed in soil as a result of its compaction. Following the expander, pipes are pushed into the channel, which is usually done with a transition width of up to 12 m. With wider transitions, pipes are tightened into the channel with the help of a demountable rod with its reverse movement. For this purpose rod is pushed to opposite side of transition, to its end length of pipe is pushed, which is fixed with the help of washer and nut. The ends of the pipes after their laying on the passages are immediately closed with plugs to prevent clogging.

Cable installation.

Installation of the cable is carried out in specially equipped installation measuring laboratories that protect the fiber connection to be performed from dust, humidity and temperature drop. The cable is installed in the following process sequence:

Clean the cable ends of dirt and enter the measuring laboratory;

Cable ends are laid on mounting table;

Cutting the cable ends for installation in accordance with the process instruction for a specific type of coupling;

Power element of cable is spliced;

Optical fibers are connected;

The connected fibers are placed and fixed in a cartridge with an acceptable bending radius;

Casing of cassette with laid fibres is closed and outer covers of cable are restored.

The central power element in the form of a steel cable at both ends of the cable is released from the plastic shell and the coupling centers are connected by soldering with solder POSS-30 and using P5K-26M paste. Soldering area is isolated by polyethylene sleeve.

Conclusion

In this course work, a fibre-optic transmission line Mogilev-Krasnopolye was designed. This transmission line will operate on the digital transmission system SOPKA - 3M.

To establish communication between the endpoints, we obtained a maximum regeneration length of 107.6 km from the results of the calculation. Since the total length of the route is 108 kilometers, one UXO will be required on this route. It can also be seen from the calculations that the attenuation value at the regeneration sites will be 18.48dB out of the 33dB norm, the bandwidth is 7.3GHz, the critical wavelength is 1.06 μm and the critical frequency is 183.06 THz.

Based on this, it can be concluded that this fiber optic link will operate at the desired speed and provide high transmission quality.