Practical experience: Gradual Analysis of Optical Cable Network laying and testing (1)

As optical fiber transmission technology matures and the price of Optical Fiber becomes lower and lower, traditional coaxial cable transmission is increasingly unable to adapt to the development of optical network today, it has the advantages of low transmission loss, long transmission distance, working bandwidth, and strong anti-interference ability, making it the most ideal carrier for optical network communication. The optical fiber is made of extremely pure Z. Only single-mode optical fiber is used in optical fiber cable TV. The diameter of the package layer is 125 μM, the diameter of the buffer layer is 250 μm, and the core diameter of the optical fiber part is only 8 ~ 10 μm. The laying and construction of optical cables should be considered in roughly the same way as that of cable engineering. However, the optical fiber has poor tensile and lateral pressure resistance and is easy to break. Therefore, it has high technical requirements in terms of construction methods, technical requirements, and process flows, high precision, dry cleaning, and high technical knowledge and operation skills are required for testing instruments, tools, and auxiliary materials.

The construction of optical cables is roughly divided into the following steps: Preparation, route engineering, laying of optical cables, connection of optical cables, and project acceptance.

1. Preparations

(1) check whether the design materials, raw materials, construction tools and equipment are complete. The equipment for optical fiber fusion is the responsibility of the manufacturer.

(2) build a high-quality construction team. This is important because the fiber construction is much stricter than the cable construction requirements, and any negligence in the construction may cause the fiber loss to increase or even cut the core.

2. Routing Engineering

(1) Before laying optical cables, you must first make a careful investigation of the routes used by the optical cables, learn about the local road construction and planning, and try to avoid these potential risks, such as pitfall, wheat farms, and gas stations. After the route is determined, the actual length is measured to be within 50 MB. It also includes natural bending and various reserved lengths during the laying, and other special reserved values such as bending in the inserting hole, reserving on the rod, reserving at both ends of the joint, and increasing the horizontal radian. In order to re-connect the optical cable when it is broken, a certain margin should be left at each hundred meters. The margin length is generally 5% ~ 10%, according to the actual length of the order, and specify when around the disk.

(2) Draw the path construction drawing. Number the pre-planted pole, draw the path construction drawing, and describe the number of each pole or underground pipe outlet pole and the pipe length, and determine the length and position of the margin. In this way, the length of the optical cable can be effectively used and reasonably configured to minimize the number of weld points.

(3) it is best to place the two optical fiber links in a flat terrain and a stable geological location to avoid water ponds, rivers, ditches and roads. It is best to set them at the pole or pipe exit, the head of the optical fiber cable shall be placed at 0.5 ~ next to the pole ~ About 1 m, this work is called "configuration disk ". Reasonable disk configuration can reduce the weld points. In addition, the position of the weld point should be specified in the construction drawing. When the optical cable has a breakpoint, it is easy to quickly find the breakpoint with the instrument for repair.

3. Laying Optical Cables

(1) For a batch of optical fiber, the diameter of the optical fiber field is basically the same. After the optical fiber is disconnected at a certain point, the mode fields between the two ends can be regarded as the same, therefore, the impact of the Mode Field Diameter on the optical fiber fusion loss can be minimized by disconnecting the point. Therefore, the optical fiber manufacturers are required to use the same batch of bare fiber cables for continuous production according to the required length. The cables are sequentially numbered on each disk and marked with A (red) and B (green) ends respectively, do not skip. Deploy the optical fiber cables according to the specified route sequence and ensure that the B-end of the optical fiber cables on the front must be connected to the-end of the optical fiber cables on the back, this ensures that the diameter of the two optical fiber end face is basically the same, so that the weld loss value reaches the minimum.

(2) Can I use an overhead optical cable? 7? The galvanized steel strand of N2. 2mm is used as a cable suspension cable. Cables and cables must be properly grounded, and lightning-proof and anti-electric measures should be taken, as well as shockproof and windproof mechanical properties. The horizontal and vertical distance between the overhead cable and power line is more than 2 m, the minimum height from the ground is 5 m, and the minimum distance from the roof is 1.5 m. There are three types of hanging optical cables: Hanging cable support, winding cable and self-bearing cable. The self-built cable does not need to be twisted and hashed, and the optical cable is drooping, so it is often used for hanging.

(3) Deploy the optical fiber cables. Because the cable reel length is longer than the cable length and can reach several thousands of meters, it is subject to the allowable rated tension and bending radius restrictions. During construction, pay special attention not to force and twist. Generally, the cable tension is about 150 ~ 200 kg. The bending radius of the optical cable must be greater than or equal to 10 ~ of the outer diameter of the optical cable ~ 15 times, the bending radius of the construction layout should be greater than or equal to 20 times. In order to avoid the optical fiber cables placed in the middle of the road section and about 20 m away from the pole, the first half of the first half is set up and the second half is put down from the disc, place the data on the ground in the 8-type font, and then deploy the data.

(4) When deploying optical cables, it is strictly prohibited to make small turns and twists and turns on the optical cables, and to provide a certain number of walkie talkie devices. The cabling method of "front heel, top shoulder of Optical Cable" is as follows, it can effectively prevent the occurrence of the back buckle, but also pay attention to the uniform force, the traction does not exceed 80% allowed by the optical cable, the maximum instant traction does not exceed 100%. In addition, special personnel should be responsible for the bending or complex terrain of the optical cable during erection, and vehicle rolling is prohibited. A slide is used to distribute optical cables in an overhead frame. The pulley is pre-mounted on the frame bar and hanging wire (generally every 10 ~ 20 m mounted on a pulley), reducing the sag at the guide pulley and the guide pulley, reducing the tension. Then wear the Traction Rope between the pulleys, fasten the traction head of the optical fiber cable, use certain traction to make the optical fiber cable climb the frame Pole, hanging on the hanging wire. The distance between the optical cable Hooks is 40 cm. The hooks must be in the same direction as the buckles on the cable. Each Pole must have a convex drip trench, each optical cable must have a pole length plus 3 m margin at the joint, so that the connecting box can be connected to the ground, and there must be a certain disk at several hundred meters.