Optical fiber types are divided into indoor optical cables, outdoor optical cables, branch optical cables and distribution optical cables according to different use occasions.
Optical fibers can be divided into single-mode and multi-mode according to the transmission mode, so single-mode optical fibers are generally used for monitoring.
Single-mode optical fiber: An optical fiber that only transmits one mode of optical signals. Generally, there are transmission levels such as G.652, G.653, G.654, and G.655. Single-mode optical fiber transmits 100M signals. The distance can reach tens of kilometers.
Multi-mode optical fiber: An optical fiber that can transmit multiple modes of optical signals. It is G.651 grade. It is divided into OM1, OM2 and OM3 according to the optical mode. Multi-mode optical fiber can transmit 100M signals with a maximum transmission distance of 2 kilometer.
Optical fiber laying method: Conventional outdoor optical cables use loose tubes as the fiber core container, which is the most common fiber core laying method.
Indoor optical cables are commonly laid in tight sleeves.
Optical cable structure: The most common optical cable structure is a layered optical cable. Optical cables with more than 12 cores generally have this structure. The optical cable cavity can accommodate multiple loose tubes, with loose tubes as the basic unit. Each loose tube can accommodate 6-12 cores; the stranded optical cable is the central strengthening member, and the loose tube surrounds the central strengthening core. For practical application, the fiber core needs to be covered with different colors, a total of 12 colors , and the number of loose tubes of the layer-stranded optical cable is generally within 12, so the number of cores of the layer-stranded optical cable is generally from 12 cores to 144 cores.
The structure generally used for outdoor optical cables with less than 12 cores is the central bundle tube type. This type of optical cable contains a central loose tube inside, which can contain 1-12 cores, and the outer sheath contains two Parallel wire.
Ribbon optical cable, also called skeleton trough structure, is generally used as an optical cable structure with a large number of cores.
ODF optical fiber distribution frame and optical coupler: In some large and medium-sized monitoring projects, ODF optical fiber distribution frame and optical coupler and other equipment may be used. ODF optical fiber distribution frame is mainly used in computer rooms. , which can make many optical fibers more organized and convenient for maintenance.
Fiber optic transceiver: also known as photoelectric converter, a device that converts optical ports and electrical ports. It is used in pairs. The electrical port is connected to the switch and the optical port is connected to the optical fiber pigtail.
Fiber optic module: Fiber optic module is mainly used in fiber optic switches. The fiber optic pigtail can be directly connected to the switch through the fiber optic module, eliminating the need for fiber optic transceivers. However, the price of fiber optic switches is relatively high.
Tips on optical fiber: 1. The tensile strength of optical fiber is very high, close to the tensile strength of metal; 2. The ductility of optical fiber (1%) is worse than that of metal (20%); 3. When optical fiber If there are cracks, bubbles or debris in the fiber, it is easy to break under a certain tension; 4. The optical fiber is easy to break due to rain, and the shear loss is greatly increased; 5. At low temperatures, the loss increases as the temperature decreases.
