Fiber optic cable is a type of communication cable that consists of two or more glass or plastic fiber optic cores located within a protective coating and covered by plastic PVC outer sleeves. Signal transmission along internal optical fibers typically uses infrared radiation.
1. Selection of the number of fiber optic cable cores
Under convenient construction conditions, try to choose optical cables with larger coil lengths. When selecting the number of fiber optic cable cores, it is necessary to combine the benefits with long-term planning, and fully consider the possibility of expansion; According to the guiding ideology of "building a line to serve a large area", fully consider the communication needs of major units along the way.
2. Selection of Fiber Optic Cable Structure Program
Long distance trunk optical cables should use single mode optical fibers with a wavelength of 1310nm and can be used within a 1550nm window; The fiber optic screening tension should not be less than 5N (Newton); Non metal pair optical cables can be used. In areas with severe lightning strikes or strong noise, non-metallic components can be used to strengthen the core of the optical cable. The core of the optical cable adopts an oil filled structure.
The regulations for selecting the protective layer structure of optical cables: for overhead and pipeline optical cables (simple plastic pipes and pipelines), the moisture-proof layer+PE outer protective layer is used; The directly buried optical cable consists of a moisture-proof layer, a PE inner protective layer, a steel strip armor layer, and a PE outer protective layer; The underwater optical cable consists of a moisture-proof layer, a PE inner protective layer, a thick steel wire armor layer, and a PE outer protective layer.
The mechanical properties of the optical cable should comply with the provisions in Table 1.1. The optical cable bears short-term allowable tension or lateral pressure, and the attenuation of the optical fiber does not change after the tension or lateral pressure is relieved, and the elongation of the optical fiber is not more than 0.15%; When the optical cable is subjected to long-term allowable tension or lateral pressure, the attenuation of the optical cable does not change, the elongation of the optical cable is not greater than 0.2%, and there is no strain before the light.
3. Selection of underwater optical cables
Main navigation rivers with a large number of navigable motor boats, sailboats, and rafts should use steel wire armored optical cables; When the river flow rate is particularly rapid and the river channel changes greatly, double-layer steel wire armored optical cables should be used; Plain rivers with a width (between two embankments or natural banks) greater than 150 meters should use steel wire armored optical cables; Although some rivers have a width of less than 150m, they have high flow velocity (over 3m/s), loose riverbed soil, easy erosion and collapse on both banks, bumpy or rocky riverbed, and large pebble riverbed. Only underwater optical cables with rigid wire armor should be used; Although the width of some rivers is not greater than 150m, the riverbed soil is stable, the flow velocity is very small, the river channel is straight and there is no erosion phenomenon, so rigid wire armored underwater optical cables may not be used; Mountain rivers should be determined based on the soil quality of the riverbed, flow velocity, flow rate, degree of erosion, and upstream hydrological conditions. The installation of backup underwater optical cables takes into account the following factors: large rivers; Large rivers with poor riverbed stability; There are other special requirements; Due to natural terrain and construction conditions, the safety level of optical cables is poor or it is difficult to repair them.