In the monitoring system, optical fiber is the connection method that can provide the best bandwidth performance among all. During the process of using optical fiber transmission, image quality is only affected by three factors: the camera, the environment and the monitor. However, the optical fiber transmission system can transmit images to a long distance without distorting the signal, nor will it reduce the clarity or details of the image. It can be said that optical fiber transmission is the lifeline of the monitoring system.

Types of optical fibers

By application scenarios: indoor optical fibers, outdoor optical fibers, branch optical fibers, and distribution optical fibers.

By laying method: self-supporting overhead optical fibers, pipeline optical fibers, armored underground optical fibers and submarine optical fibers.

According to the structure of optical fibers, they can be classified as: bundle tube optical fibers, stranded optical fibers, skeleton optical fibers, clamp-on optical fibers, ribbon optical fibers, non-metallic optical fibers and branched optical fibers.

By application: long-distance communication optical fibers, short-distance outdoor optical fibers, hybrid optical fibers and optical fibers for use in buildings.

By transmission mode: single-mode and multi-mode. Monitoring generally uses single-mode optical fibers.

Optical fiber switch products

Single-mode optical fiber: A type of optical fiber that transmits only one mode of optical signal. Commonly, it is classified into transmission grades such as G.652, G.653, G.654, and G.655. Single-mode optical fiber can transmit 100-megabit signals over distances of tens of kilometers. Single-mode optical fibers only transmit the main mode, meaning that light travels along the core of the fiber. Due to the complete avoidance of mode dispersion, the transmission frequency band of single-mode optical fibers is very wide, making them suitable for large-capacity and long-distance optical fiber communication. The wavelength of light used in single-mode optical fibers is 1310nm or 1550nm.

Multimode optical fiber: Optical fiber capable of transmitting various optical signals is of grade G.651. It is classified into OM1, OM2, and OM3 based on the optical mode. The maximum transmission distance of a 100-megabit signal through multimode optical fiber is 2 kilometers. Multimode optical fiber, at a certain working wavelength, has multiple modes transmitted within the fiber. This type of optical fiber is called multimode optical fiber. Due to dispersion or aberration, the transmission performance of this type of optical fiber is poor, the frequency band is relatively weak, the transmission capacity is small, and the distance is short.

2. Optical fiber laying methods and requirements

Conventional outdoor optical fibers are all containers with loose tubes as the core, which is the most common way to lay the core of optical fibers. Indoor optical fibers are commonly laid in a tight-fitting manner. The cores of large-core-count optical fibers are also combined and laid in a band-like manner.

The laying requirements for optical fibers: 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 optical fibers, the rotation of the optical fiber disk should be synchronized with the laying speed. The speed of the optical fiber index is generally 15 meters per minute. When laying optical fibers, the outlet of the optical fiber should maintain a loose arc and retain a buffer allowance, but not too much to avoid the formation of back clips on the optical fiber. The length of the optical fiber is reserved at both ends at 5 to 10 meters. When laying optical fibers, labels should be properly made and the cable retraction records should be filled out. All optical fibers should not be exposed.

Optical fiber monitoring

3. Selection of optical cores

The number of cores refers to the quantity of glass fibers contained in each optical fiber.

First, it is necessary to know the number of wiring points on this layer, calculate the number of switches, and determine whether the connections between switches are stacked or not. If the stacking is carried out and the core switch is dual-server hot standby redundancy, 6 cores will be sufficient. If a switch is not stacked and requires 4 cores, multiply the number of switches by 4 and add the redundancy of 4 cores, and that's it. Hot backup: Both are in working condition simultaneously; Cold backup: The backup device is in standby mode.

4. Precautions

The selection of optical fibers involves not only the number of fiber cores and the type of fiber, but also choosing the outer sheath of the fiber based on its usage. The following are the precautions:

When outdoor optical fibers are directly buried, armored optical fibers should be selected. When they are overhead, black plastic sheathed optical fibers with two or more reinforcing ribs can be used.

(2) When selecting optical fibers for use within buildings, attention should be paid to their flame-retardant, toxic and smoke-producing characteristics. Generally, in pipelines and areas with forced ventilation, flame-retardant and smoke-producing types can be chosen. In exposed environments, flame-retardant, smoke-free and non-toxic types should be selected.

(3) When vertical wiring is carried out within a building, stranded optical fibers can be selected. When laying horizontally, branch optical fibers can be selected.

(4) Multimode optical fibers can be selected for transmission distances within 2 kilometers. For distances exceeding 2 kilometers, relay or single-mode optical fibers can be selected.

The basic and common methods for choosing optical fibers during the engineering process are those we have introduced today. However, it should be reminded that the engineering environment is complex and diverse, and various problems may arise. Therefore, we need to strictly follow the wiring standards during planning and construction. When encountering problems, we should analyze them flexibly.