Introduction to the design steps of fiber optic connection

In the current two-way network transformation, fiber-to-cell, fiber-to-the-building and even fiber-to-the-home have become a reality. The application of optical fiber is unprecedented. How to better utilize the fiber transmission bandwidth, large communication capacity, low loss, and no electromagnetic interference. The advantages of small diameter, light weight and abundant raw materials are worthy of our attention. Light is transmitted through the fiber, which is mainly caused by the transmission loss of the fiber itself and the splice loss at the fiber connector. Once the fiber optic cable is ordered, the transmission loss of the fiber itself is basically determined, and the splice loss at the fiber connector is related to the fiber itself and the on-site construction. The steps and methods of the fiber optic cable connection project are now introduced.

1 Design and drawing of optical fiber continuous drawings

(1) The choice of the number of cores for the fiber. Our county has newly set up optical nodes to arrange 4-core optical cables, one optical fiber to transmit downlink signals, one to transmit uplink signals, and one to transmit digital signals, plus one reserved one. At the same time, when considering that several optical nodes are in the same direction, it is convenient for erection, and the distance of the distance is different, and the optical fiber used at the farthest point is included in the optical cable which is close to the front end, for example, three optical nodes are in the same In the direction, each core is set with 4 core fibers. When the optical cable is installed, a 12-core optical cable is used between the front end and the first optical node, and an 8-core optical cable is used between the first optical node and the second optical node. A 4-core optical cable is used between the optical nodes and the third optical node, so that the multi-fiber common cable saves investment.

(2) Drawing of the optical cable connection drawing. After designing the number of fiber cores, and then drawing the cable connection drawing, a complete cable connection route diagram should be composed of optical link schematic, cable splicing diagram, cable routing diagram, optical cable connection routing diagram, optical link loss table, etc. composition. Before the cable is connected, the planning and design department provides the cable welding diagram to the construction department. The cable welding diagram describes the components of the cable fusion, including the location of the optical package, the cable routing, the number of cables, the number of cores, the cable profile, and the cable docking. Figure and so on. Cable splicing, loose tube, fiber chromatography, cable

A cable is a wire product used to transmit electrical energy information and achieve electromagnetic energy conversion. There are both conductors and insulation layers, and sometimes a tight inner sheath to prevent moisture intrusion, or an outer sheath with high mechanical strength. The structure is more complicated, and the product with a large cross-sectional area is called a cable.

Chromatography blue, orange, green, brown, gray, natural, red, black, yellow, purple, and common fiber chromatography, ^^^ white, light red, can be ranked before the corresponding color, cable chromatography A more uniform specification can be formed in the design and construction of optical cable engineering, which is easy to remember and organize.

2 Cable connection steps

The heat-shrinkable tube is flame-retardant, insulating and temperature-resistant. The heat-shrinkable sleeve is a special polyolefin heat-shrinkable sleeve, also called EVA material.

It should be penetrated before stripping, and it is strictly forbidden to penetrate after the end face is prepared.

(2) Preparation of the end face. The preparation of the fiber end face includes stripping, cleaning and cutting. A qualified fiber end face is a necessary condition for welding, and the end face quality directly affects the welding quality. The stripping of the fiber coating layer should be mastered by the flat, stable and fast stripping method. “Ping., that is, the fiber should be flat. The left thumb and forefinger pinch the fiber to make it horizontal. The exposed length is about 5 cm. The remaining fiber is naturally bent between the ring finger and the little finger to increase the strength and prevent slipping. "Stable. That is, the stripping pliers should be held steady. "Fast", that is, stripping fiber is fast, the stripping pliers should be perpendicular to the fiber, tilted at an angle in the upper direction, then gently clamp the fiber with the jaws, and then apply the force with the right hand, and push the fiber axially flat, the whole process Be natural and smooth, in one go. For the cleaning of bare fiber, first observe whether the coating layer of the fiber stripping part is stripped. If there is residue, it should be stripped. If there is a very small amount of coating layer that is not easy to be stripped, use a cotton ball to dip it with an appropriate amount of alcohol. except. Tear the cotton into small flat-shaped fan-shaped pieces, dip a little alcohol (preferably with two fingers, no overflow), fold into a "V" shape, clamp the stripped fiber, and wipe the fiber in the axial direction, striving for a success. After a piece of cotton is used 2 to 3 times, it must be replaced in time. Each time you want to use different parts and layers of cotton, this will not only improve the cotton utilization rate, but also prevent the two pollution of the fiber. Cutting is the most critical part in the preparation of fiber end faces. Precision and excellent cutting tools are the basis, and strict scientific operation specifications are guaranteed. First check the drawings and materials, and understand the placement of the type of fiber in this connection. It should pay attention to the “front and back 掀, advanced retraction”, that is, the hand-held fiber, slightly ahead of the scale requires flat placement of the guide groove, the rear part is slightly lifted up, so that The front half of the fiber is pressed against the bottom of the guide groove, and then pulled back to the required scale to ensure that the fiber is “V. guide groove and perpendicular to the cutting edge. When cutting, the action should be natural, stable, not heavy, not urgent, avoid fiber breakage, The generation of bad end faces such as bevels, burrs, and cracks.

(3) Fiber fusion. Fiber fusion is the central link in the continuous work, so scientific operation in the high-performance fusion splicer and welding process is necessary. Before welding, according to the material and type of the fiber, set the key parameters such as the best pre-melting main melting current and time and the fiber feeding amount. During the welding process, the welded “V” shaped groove, electrode, objective lens, welding chamber, etc. should be cleaned in time to observe whether there are any bubbles, too thin, too thick, virtual fusion, separation, etc. in the welding, pay attention to the OTDR tracking monitoring results, timely Analyze the causes of the above-mentioned undesirable phenomena and take corresponding improvement measures. If the phenomenon of fuzzing occurs multiple times, check whether the materials and models of the two welded fibers match, whether the cutter and the fusion splicer are contaminated by dust, and check the oxidation status of the electrode. If there is no problem, the welding current should be properly increased.

(4) Disc fiber. Disc fiber is a technology and an art. The scientific method of fiber-optic fiber can make the fiber layout reasonable, the additional loss is small, the time of passage and the harsh environment can be tested, and the fiber breakage caused by the extrusion can be avoided. The method of disc fiber: 1. First, the middle and the back side, that is, the heat-shrinkable sleeves are placed one by one in the fixing groove, and then the residual fiber on both sides is processed, which is beneficial to protect the fiber joints and avoid damage caused by the fiber. 2. Start the fiber from one end, that is, from the fiber tray on one side, fix the heat shrinkable tube, and then process the remaining fiber on the other side. This is convenient and fast, and avoid sharp bends and small circles. 3. Special case treatment, such as individual fiber is too long or too short, it can be placed in the last individual coil, with special optical device, it can be processed separately, if it is common with ordinary fiber, it should be light Placed on a common fiber, with a cushion pad between them to prevent the fiber from being broken by the extrusion, and the tail of the special optical device should not be too long. 4. According to the actual situation, use a variety of graphics fiber, according to the length of the fiber and the size of the reserved disk space, naturally coiled, do not pull hard, should be flexible use of round, oval, CC, ~ a variety of graphics fiber (note R ) 4 cm ), make the most of the reserved disk space and reduce the additional loss caused by the fiber.

(5) Optical cable connection quality inspection. Strengthening the monitoring of OTDR is of great significance to ensure the quality of the fusion of the fiber, to reduce the additional loss caused by the fiber and the damage that the casing may cause to the fiber. The OTDR 4-channel monitoring program must be strictly implemented throughout the connection process:

1. In real-time follow-up monitoring of each core fiber during the welding process, check the quality of each melting point; 2. After each disk fiber, carry out an inspection of the disk fiber to determine the additional loss caused by the disk fiber; Before connecting the boxes, measure all the fibers to find out whether there is any leakage test and whether the fibers and connectors are squeezed between the fiber reservation disks. 4. After the box is sealed, check all the fibers to check whether the package is sealed. Damage to the fiber. After 4 tests, the cable connection loss test table is recorded in detail.

The fiber optic cable connection box is where the end of the fiber optic cable is connected, and then accesses the optical switch through an optical jumper.

Fixed and residual cable handling. The horizontally connected box of the buried well should be first on the ground, with the box as the reference point, the cable will be coiled, then dragged into the well, and the well wall will be divided into four directions, up and down, and tied with anti-rust tie. Do not use thin wire to hang. The vertical joint box of the club head should pay attention to the horizontal steering of the box body, so that the cable entering and exiting the cable is naturally twisted and the bending curvature of the cable is controlled. The specific operation method: 1 multi-person operation forms a party with one cable and one pull, in principle, One person at the box and each remaining cable frame is forbidden to sing a double spring, and if necessary, a walkie-talkie to enhance contact. 2 First and the middle two sides, that is, the flat box body, fix it on the steel wire, and then deal with the remaining cables on both sides. When the remaining cable itself has a twisting phenomenon, advance it along the steel wire to the opposite end in advance. When it is not necessary to dispose of the residual cable, the box body should be fixed first, and the remaining cable part should be hanged to the opposite end of the head. Beware of damage to the connection box and the fiber inside it during the second construction.

(7) Optical cable connection record. After the completion of the optical cable, make timely records, including sequence, core number, chromatogram, and connection loss.