other product

The classification of optical cables in security monitoring engineering, how to choose the type when designing

by:Keyable     2021-08-05
The classification of optical cables in security monitoring projects, and how to select them when designing. In today's high-definition surveillance camera system applications, optical fibers are the one that can provide the best bandwidth performance among all connection methods. When using an optical fiber transmission system, the image quality of the system is only limited by the three factors of the camera, environment and monitor. The optical fiber transmission system can transmit the image to a very far place without any form of distortion of the signal. It will not detract from the clarity or details of the image. It can be said that the optical fiber transmission system is the lifeline of the entire monitoring system. 1. Types of optical fibers: Optical fibers are divided into indoor optical fibers, outdoor optical fibers, branch optical fibers, and distribution optical fibers according to different occasions. 1. According to the laying method: self-supporting overhead optical fiber, pipeline optical fiber, armored buried optical fiber and submarine optical fiber. 2. Divided according to fiber structure: bundle tube type fiber, layered fiber type, skeleton type fiber, tightly type fiber, ribbon type fiber, non-metal fiber and branchable fiber. 3. Divided by purpose: optical fiber for long-distance communication, short-distance outdoor optical fiber, hybrid optical fiber and optical fiber used in buildings; 4. Optical fiber can be divided into single-mode and multi-mode according to the transmission mode, and single-mode optical fiber is generally used for monitoring. 5. Single-mode optical fiber: optical fiber that transmits only one mode of optical signal. Conventionally, there are transmission grades such as G.652, G.653, G.654, and G.655. The single-mode optical fiber can transmit hundreds of megabytes of signals up to dozens of distances. kilometer. Single-mode fiber only transmits the main mode, that is to say, the light is only transmitted along the inner core of the fiber. Because the mode dispersion is completely avoided, the transmission frequency band of single-mode fiber is very wide, so it is suitable for large-capacity, long-distance optical fiber communication. , Single-mode fiber uses light wavelength of 1310nm or 1550nm. 6. Multi-mode optical fiber: optical fiber capable of transmitting multiple modes of optical signals. It is of G.651 grade. According to the optical mode, it is divided into OM1, OM2, OM3. Multi-mode optical fiber transmits 100M signals with a maximum transmission distance of 2 kilometers. Multimode fiber, under a certain working wavelength, there are multiple modes transmitted in the fiber. This kind of fiber is called multimode fiber. Due to dispersion or aberration, the transmission performance of this kind of fiber is poor. The frequency band is relatively narrow and the transmission capacity It is relatively small and the distance is relatively short. 2. Optical fiber laying methods and requirements: Conventional outdoor optical fibers use loose tube as the core container, which is the most common optical fiber core laying method; indoor optical fibers are usually laid in a tight-buffered manner; fiber cores with large core counts are also used The fiber core is assembled in a ribbon mode. 1. The laying requirements of the optical fiber: the bending radius of the optical fiber should be at least 15 times the outer diameter of the optical fiber, and at least 20 times during the construction process; when laying the optical fiber, the rotation of the optical fiber tray should be synchronized with the laying speed, and the optical fiber index should be The speed is generally 15 meters per minute; when laying out the fiber, keep a slack arc at the fiber exit, and reserve a buffer margin, and it should not be too much to avoid back buckling of the fiber; the reserved length of the fiber at both ends is 5- 10 meters; labels should be made when laying optical fibers, and the pay-off record should be filled in; all optical fibers should not be exposed. Third, the choice of optical core: the number of cores is the number of glass fibers contained in each optical fiber. The following editor will introduce some methods to determine the number of fiber cores. 1. First, clearly know the number of wiring points on this layer, calculate the number of switches, and whether the connections between switches are stacking or not stacking. If stacking, the core switch is dual-system hot standby redundancy, 6 cores are enough (2 cores each use 2 cores, and 2 cores are redundant). If you do not need to stack a switch with 4 cores, multiply the number of switches by 4 plus 4 cores for redundancy. (Note: Redundancy: as long as there is more than used, the more redundant is called redundant primary and standby: one is used, the other is exactly the same as backup; hot backup: both in working state at the same time; cold backup: the backup device is in Standby state.) 2. Experience method: each floor wiring closet (horizontal wiring cabinet), set up an optical fiber, generally six cores: two cores used, two cores standby, two cores redundant; there are also eight core optical fibers of. The standard 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, and it is more appropriate to leave more than 2 cores as a backup. The above is an introduction to the method of determining the number of optical fiber cores. The backup can be selected according to the person, so the number of fiber cores that come out is quite different. According to the specification, it is only necessary to ensure a minimum selection and add a backup core number. Fourth, matters needing attention: In addition to the number of fiber cores and fiber types, the selection of optical fiber should also be based on the use of the optical fiber to choose the outer sheath of the optical fiber. When selecting, pay attention to the following points: 1. When the outdoor optical fiber is directly buried, it is appropriate Choose armored optical fiber. When overhead, you can choose two or more reinforced ribbed black plastic outer sheathed optical fibers. 2. When selecting the optical fiber used in the building, attention should be paid to its flame retardant, toxic and smoke characteristics. Generally, flame retardant and smokey types can be selected in ducts and forced ventilation, and flame retardant should be used in exposed environments. , Smokeless and non-toxic type. For vertical wiring in the third floor, stranded optical fibers can be used; for horizontal wiring, branch optical fibers can be used. 4. Multi-mode fiber can be used for transmission distance within 2km; relay or single-mode fiber can be used for more than 2km. Chengdu Security Monitoring System: The above are only a few issues considered from the application side, and they need to be flexibly mastered during implementation. In fact, the wiring environment is complex and diverse, and various problems may appear at any time. This requires us to strictly implement the wiring standards during planning and construction. When we encounter problems, we can analyze them flexibly and we will be solved satisfactorily.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...