Optical fiber splicing and testing project

Optical fiber communication technology in the last 20 years, the rapid development of new technology, as large amount of information transmission optical fiber communication, and rate, and digital information, send a digital signal, thereby broad-band image signals, computer networking and other information transmission is possible.Loss measurement of optical fiber is very important, it is directly related to the quality of fiber-optic communications, and to detect possible point of failure.1, the fiber splice

(1) the fiber splice. Fiber connecting principles to be followed are: core number equal to the same beam pipe of the corresponding color fiber optic butt, core number is not the same core sequence first, then the number of large, followed a few small core.

(2) fiber connecting the following methods: welding, active connections, mechanical connection three. Most of the use of welding in the project method. This welding method using the contact loss, return loss, high reliability.

(3) fiber connecting the process and steps:

① stripping cable and cable box fixed to follow. Be careful not to damage the beam pipe, stripping length to take 1m or so, wipe clean with toilet paper will ointment, cable penetration will continue box, be sure to compress the fixed wire, not loose. Otherwise, it may cause broken fiber roll core.

② splitting the fiber through the heat-shrinkable tube. Different beam tube, the fiber in different colors separately, through the heat-shrinkable tube. Stripped of the fiber coating is very fragile, use heat shrink tubing, can protect the optical fiber splicing head.

③ Open Furukawa s176 welding machine power source, use a preset program for 42 kinds of welding, and in use and after use to remove welding machine in the dust, especially fixture, the mirror and v-groove pieces of dust and fiber not. catv use of conventional single-mode fiber and dispersion-shifted single-mode optical fiber, Wavelength 1310nm and 1550nm are also two. So, before welding system according to the fiber and the operating wavelength to select the appropriate welding procedures. If no special circumstances, generally use automatic welding process.

④ making optical fiber end face. Fiber production will directly affect the continuation of quality, so be sure to do the welding qualified before the end. With special strippers strip coating, then dipped in alcohol to clean bare fiber on the cotton cloth several times, hard to moderate, and then cut with a precision optical fiber cleaver, for 0.25mm (outer coating) fiber, Cut a length of 8mm-16mm, for 0.9mm (outer coating) fiber cut length only 16mm.
⑤ to place fiber. The fiber on the welding machine v-shaped slot, careful pressure on the optical plate and fiber fixture, set according to the length of optical fiber cutting position in the platen, close the draft shield, welding can be done automatically, in just 11 seconds.

⑥ out of the optical fiber furnace heat shrink tube. Open the windscreen, the fiber removed from the welding machine, and then heat shrink tubing on the bare fiber center, into the furnace heating. Micro-heater can be used 20mm and 40mm and 60mm heat-shrinkable tubing heat shrink tubing generally, 20mm heat shrink tubing to be 40 seconds, 60mm heat shrink tubing is 85 seconds.

⑦ fiber plate fixed. Will continue to splice a good optical disk drive, the disc fiber, the larger the disk radius circle, the greater the curvature, the smaller the loss of the entire line. So we must maintain a certain radius, where the laser transmission in the core, to avoid unnecessary losses.

⑧ seal and suspend. Field continuation box must be sealed to prevent the water. Splice box water, due to fiber and fiber splices long-term immersion in water, there may be some increase in optical attenuation. Wear a stainless steel hook and hang the hanging line. Thus, the optical fiber fusion complete.

2, the fiber tested

Optical fiber in the erection, welding testing is completed, the equipment used mainly otdr tester, with the Canadian exfo's ftb-100b Chinese color touch screen otdr portable tester (dynamic range of a 32/31, 37.5/35, 40/38 , 45/43db), can test the location of fiber break; fiber link of the whole loss; about the loss along the fiber length distribution; fiber splice point connector loss. To test the accuracy, otdr tester pulse size and width to the appropriate choice, given the refractive index n according to the factory value of target setting. In determining the point of failure, if the cable length is not known in advance, can be placed automatically otdr, identify the failure point of the general location, and then on the Advanced otdr. The pulse width and choose a smaller size, but with the cable length to correspond with the coordinates line up reducing the blind spots overlap, the more accurate the smaller the width, of course, the curve shows the pulse is too small to appear after the noise, to be just right. Then there plus access probe fiber plate, the purpose is to prevent blind spots is not easy to find near there. Criteria for determining the breakpoint, the breakpoint does not follow if the box office, near the splice box will open, connected otdr tester, test failure point the exact distance from the test point, the use of fiber optic cable on the meter scale is very easy to find fault . Standard troubleshooting using meters, the type of layer stranded cable, and a strand rate problem, and that is the length of cable and fiber length is not equal to the length of the fiber is about 1.005 times the length of the cable, using the above method can be successfully excluded multiple breakpoints, and high-loss points.

Cable construction can be divided into the following steps: preparation route works → → → Cable laying fiber optic cable connecting → project acceptance.

1. Preparation

(1) Check the design data, materials, construction tools and equipment are complete.

(2) the formation of a high-quality construction team. This is critical because the fiber optic cable construction than to much more stringent construction requirements, the construction of any negligence will cause fiber loss increases, even off the core.

2. Route Project

(1) fiber optic cable laying before the first of the route through which to do serious investigation to understand the local road construction and planning, as much as possible to avoid the ponds, the wheat field, gas stations, etc. These potential pitfalls. After routing to determine its length to do the actual measurement, accurate to within 50m. Plus, when laying aside the natural bend and a variety of lengths, including a variety of reserve into the hole bending, rod aside, the joint reserve at both ends, horizontal curvature increases, and other special reserve. To make cable break occurs again in the continuation should be in every hundred meters left a certain margin, margin length is usually 5% to 10%, according to the actual needs of the length of the order, and in the disc around the state.

(2) drawing the path construction plans. Good poles planted in the pre-numbered, draw the path construction plans, and describe each pole or underground pipe outlet pipe length and the number of poles, and set the margin need to stay out of the length and location. This efficient use of fiber optic cable length, a reasonable allocation to minimize the welding point.(3) erection of two fiber optic connectors at best flat in terrain, geological, stable place to avoid the reservoirs, rivers, canals and roads, the best in the pole or pipe outlet, overhead pole cable connector should fall next to the 0.5 ~ 1m or so, this work is called "distribution plate." Plate can be reduced with reasonable welding point. Also in the construction plans should also indicate on the welding position, when the breakpoint occurs when the fiber optic cable, easy to find instruments quickly break repair.

3. Cable laying

(1) the same batch of fiber, which is basically the same mode field diameter, the fiber is disconnected at some point, between the two ends of the mode field can be regarded as consistent, so this break point in the welding can weld the fiber mode field diameter minimize the impact of loss. So they requested that manufacturers use the same batch of cable bare fiber, the fiber length required continuous production, the serial numbers on each plate, and were marked with a (red), b (green) side, not dance number. Basis having set up fiber optic cable to determine the routing number along the laying order, and ensure that the front panel cable to the b-side, and after a cable connected to a side, thus ensuring the continuation of the fiber end when the two are basically the same mode field diameter, the splice loss values to a minimum.

(2) overhead cable available 7  2.2mm galvanized steel wire for hanging wire hanging cable. Hanging wire and cable to be well grounded, there must be mine, anti-electric measures, and earthquake, wind mechanical properties. Overhead power lines hanging lines and the horizontal and vertical distance to more than 2m, the minimum height from the ground 5m, minimum distance from the roof of 1.5m. Overhead cable hanging there are three kinds: prop hanging wire hanging, hanging wire winding and self-supporting. Not self-supporting steel hanging wire cutter, cable sag, force poor to withstand wind load, so commonly used hanging.

(3) overhead cable laying. As the cable reel length longer than the cable length may reach several kilometers, so by allowing the nominal tension and bending radius of the limit, special attention in the construction and the occurrence of kink phenomena can not be yanked. Generally allowable cable tension is about 150 ~ 200kg, cable bend radius should turn fiber diameter greater than or equal to 10 to 15 times, the construction should be laying the bending radius greater than or equal to 20 times. In order to avoid the cable placed in the middle of road, about 20m away from the pole at, the opposite direction to the erection of two, first set up the first half of the volume, in the later half of the volume optical cable from the drive down, press the "8" shaped manner on the ground, then laying.

(4) fiber optic cable laying, the non-cable to play a small circle and fold, twist, and be equipped with a certain number of walkie-talkies, "the former left with, fiber optic cable on the shoulder" of the release cable method, can effectively prevent the occurrence of the back button, Note also that force uniform, traction cable to allow no more than 80% of the maximum instantaneous traction does not exceed 100%. In addition, set up, turn the cable at the office or the more complex terrain should be specifically responsible, non-vehicle rolled. Use of overhead pulley laying cable car line in the frame bar and hanging pre-hung pulley (usually every 10 ~ 20m hung a pulley), the cable onto the pulley, cited under the pulley at the reduced sag, reduce tension suffered. Then put in traction between the pulley rope, cable pulling rope tied traction head, with some traction to cable pole climbing shelves, hanging in the hanging line. Cable hook spacing of 40cm, hook buckle in the direction of hanging line to be consistent, at each pole must be convex drip groove, each cable tray should be left at joints 3m rod length plus the margin, to continue case ground welding operation, and every few hundred meters to have a certain drive to stay.4. SpliceCommon type of cable has stranded, skeleton and central beam tube fiber optic cable, the color sequence is divided into core blue, orange, green, brown, gray, white, red, black, yellow, purple, pink, blue, This is called a core of full-color chromatography, some cable manufacturers with "character" with a certain color chromatography. Multi-core optical fiber cable to different colors in the same bunch of tubes into a group, so more than one core cable where there might be several beam tube. Cross-section of the cable is, the red optical beam tube as the first bunch of tubes, clockwise followed by a white, snowy white and white ... ... the last one is the green beam tube. Fiber splice, should follow the principle is: the same number of cores, the same beam pipe of the corresponding color fiber optic butt, core number is not the same core sequence first, then the number of large, followed a few small core.