The role of CVI coaxial high-definition optical terminal in video surveillance
The analog video optical terminal optical cable is divided into indoor optical cable, outdoor optical cable, branch optical cable and distribution optical cable according to the different usage occasions. Optical fiber can be divided into single mode and multi mode according to transmission mode, so monitoring generally uses single-mode optical fiber. Single mode fiber: optical fiber that transmits only one mode light signal, which is classified as G.652, G.653, G.654, G.655 and so on. Single mode fiber can transmit a hundred megabytes distance to several tens of kilometres.
Small optical fiber knowledge
1 the tensile strength of the optical fiber is very high, which is close to the tensile strength of the metal.
The ductility of 2 fiber (1%) is less than that of metal (20%).
3 when the optical fiber cracks, bubbles or debris, it is easy to fracture under the action of a certain tension.
4 optical fiber rainwater is easy to fracture and the loss is greatly increased.
5 at low temperature, the loss increases with the decrease of temperature.
6 optical fiber needs to enhance mechanical performance protection and waterproofing protection to ensure transmission performance.
Wavelength: a communication window for optical fiber communication, in which 8501310nm is a multimode optical fiber communication window, a short wavelength window, and 131015501640nm as a single mode optical fiber communication window as a long wavelength window.
Simplex: the communication signal is only received or transmitted only, one-way communication, understood as a core optical fiber only receive optical signals or send only optical signals.
Duplex: both receive signals and send signals, divided into half duplex and full duplex. Half duplex can be understood as a core core. After receiving the signal, the signal can be transmitted through the same core fiber, but the signal can not be sent at this time; and the full duplex is still using a core fiber to receive the signal. At the same time, it can send signals continuously, receive and transmit two kinds of communication, and do not interfere with each other. It is usually implemented by frequency division multiplexing, time division multiplexing and wave division multiplexing. Multimode fiber: fiber that can transmit a variety of mode light signals, for G.651 grade, according to optical mode, OM1, OM2, OM3, multimode fiber transmission hundred megabytes transmission distance of 2 km.
Optical fiber laying method
Conventional outdoor optical cable is a container with loose casing as core, which is the most common fiber core laying method.
Indoor optical fiber cable is commonly used for tight fitting.
The core of large core optical fiber cable is also combined with fiber core by ribbon.
The most common optical cable structure for fiber optic cable structure is a layer stranded cable, which is generally the structure of 12 core cables. The fiber cable cavity can accommodate a number of loose sleeves, the loose casing is the basic unit, and each loose casing can hold 6-12 core core; the layer twisted fiber cable is the central strengthening component and the loose sleeve loop is around the core strengthening core, in order to practice the core. Application, the core needs to cover different colors, a total of 12 colors, and the number of loose sleeving of the layer type optical cable is generally within 12, so the core number of the layer twisted fiber cable is generally from 12 core -144 core. The structure of the outdoor optical cable under 12 cores is the central bundle tube. The type of cable is built with a central loose tube, which contains 1-12 core core, and the outer sheath contains two parallel wires. Ribbon optical cable, also known as skeleton slot structure, is generally used as the core cable structure.
Optical fiber matching equipment
Optical fiber distribution frame (box): fiber terminal box is designed to protect fiber and tail fiber, and tail fiber is used to connect fiber transceiver, optical fiber switch or optical terminal.
Optical fiber terminal box (continuous box or fuse tray): the optical fiber junction box splits two optical fibers together.
Pigtail: one end of optical fiber pigtail is fused with optical fiber, and the other end is connected with optical fiber transceiver or optical fiber switch.
ODF fiber wiring frame and optical coupler: in some large and medium-sized monitoring projects, it may be used to ODF fiber wiring rack and optical coupler and other equipment. The main application of ODF fiber wiring frame and the machine room can make many fibers more regular and easy to maintain.
Optical fiber transceiver: also called a photoelectric conversion machine, the device that converts the aperture and the electric port, is used in pairs, the electric port is connected to the switch, and the optical port connects the fiber tails.
Optical fiber module: the main application of optical fiber module and fiber switch, through the optical fiber module can directly connect fiber optic tails to the switch and save the fiber transceiver, but the price of the fiber switch is relatively high.