Selection of Fiber Type and Number of Cores

type of fiber

Optical fibers are divided into indoor optical fibers, outdoor optical fibers, branch optical fibers, and distribution optical fibers according to different use occasions.

According to the laying method: self-supporting overhead optical fiber, pipeline optical fiber, armored buried optical fiber and submarine optical fiber.

According to the fiber structure, it is divided into: bundled fiber, layered fiber, skeleton fiber, tightly hugged fiber, ribbon fiber, non-metallic fiber and branchable fiber.

According to the purpose: optical fiber for long-distance communication, short-distance outdoor optical fiber, hybrid optical fiber and optical fiber for building;

Optical fibers can be divided into single-mode and multi-mode according to the transmission mode, and single-mode optical fibers are generally used for monitoring.

Single-mode fiber: Optical fiber that transmits only one mode of optical signal. Conventionally, there are G.652, G.653, G.654, G.655 and other transmission grades. Single-mode fiber only transmits the main mode, that is to say, the light is only transmitted along the inner core of the fiber. Since mode scattering is completely avoided, the transmission frequency band of single-mode fiber is very wide, so it is suitable for large-capacity, long-distance fiber optic communication , the wavelength of light used by single-mode fiber is 1310nm or 1550nm.

Multimode fiber: fiber that can transmit multiple modes of optical signals, G.651 grade, divided into OM1, OM2, OM3 according to the optical mode, multimode fiber transmits 100M signals with a maximum transmission distance of 2 kilometers. Multimode fiber, at a certain working wavelength, there are multiple modes transmitted in the fiber, this fiber is called multimode fiber, due to dispersion or aberration, so the transmission performance of this fiber is poor, the frequency band is relatively narrow, and the transmission capacity Smaller and shorter distance.

Optical fiber laying methods and requirements:

Conventional outdoor optical fibers use a loose tube as the core container, which is the most common fiber core laying method; indoor optical fibers are often laid in tight sleeves; the cores of large-core fibers are also combined in ribbons. core.

Requirements for laying optical fibers: the bending radius of the optical fiber should be at least 15 times the outer diameter of the optical fiber, and it should be at least 20 times during the construction process; when laying out the optical fiber, the rotation of the optical fiber reel should be synchronized with the laying speed, and the speed of the optical fiber indexing is generally 15 meters per minute; when laying out the optical fiber, the slack arc should be maintained at the outlet of the optical fiber, and the buffer margin should be reserved, and it should not be too much to avoid the back buckle of the optical fiber; the reserved length of the optical fiber at both ends is 5-10 meters ; When laying optical fibers, labels should be made and the payout records should be filled in; all optical fibers should not be exposed.

The choice of optical core

The number of cores is the number of glass fibers contained in each fiber. The following ZR Cable introduces some methods to determine the number of fiber cores.

First of all, clearly know the number of wiring points in this layer, calculate the number of switches, and whether the connections between switches are stacked or not. If the stack is stacked and the core switch is dual-machine hot standby redundancy, 6 cores are enough (2 cores each use 2 cores, and 2 cores are redundant). If you do not stack a switch to 4 cores, multiply the number of switches by 4 plus the redundancy of 4 cores, and you will be fine. (Note: Redundancy: as long as there are more than the ones used, the extra ones are called redundant master and backup: one is used, and the other is exactly the same as backup; hot backup: both are in working state at the same time; cold backup: the backup device is in standby mode.)

Experience: In the wiring room (horizontal wiring cabinet) of each floor, there is one optical fiber, generally six cores: two cores are used, two cores are reserved, and two cores are redundant; there are also eight-core optical fibers. The specification's minimum configuration is 2 cores per 48 points. Of course, 4 cores can be selected for 48 points, because 2 cores are the smallest unit of optical fiber, it is more appropriate to leave 2 more cores as backup.

The above is an introduction to the method of determining the number of fiber cores, you can understand. The backup can be selected according to the person, so the number of fiber cores produced varies greatly. According to the specification, it is only necessary to ensure a minimum selection plus a number of backup cores.