Selection, connection and detection of optical cables

Selection of optical cable:

The selection of optical cables is not only based on the number of optical fibers and the type of optical fibers, but also the outer sheath of the optical cable according to the use environment of the optical cable.

1) When the outdoor optical cable is directly buried, the armored optical cable should be selected. When overhead, an optical cable with a black plastic outer sheath with two or more reinforcing ribs can be used.

2) When selecting optical cables used in buildings, attention should be paid to their flame retardant, poisonous and smoke characteristics. Generally, the flame-retardant but smoke-bearing type (Plenum) can be used in the pipeline or forced ventilation, and the flame-retardant, non-toxic and smoke-free type (Riser) should be used in the exposed environment.

3) When cabling vertically in the building, you can choose Distribution Cables; when laying horizontally, you can choose Breakout Cables.

4) If the transmission distance is less than 2km, you can choose multi-mode optical cable. If it exceeds 2km, you can use repeater or choose single-mode optical cable.

Connect and detect

1. Optical cable connection:

The methods mainly include permanent connection, emergency connection and active connection.

1) Permanent fiber optic connection (also called hot melt):

This type of connection is to use the method of electric discharge to melt and connect the connection points of the optical fibers together. Generally used in long-distance connection, permanent or semi-permanent fixed connection. Its main feature is that the connection attenuation is the lowest among all connection methods, with a typical value of 0.01~0.03dB/point. However, when connecting, special equipment (fusion machine) and professionals are required to operate, and the connection point also needs to be protected by a special container.

2) Emergency connection (also called) cold melting:

The emergency connection mainly uses mechanical and chemical methods to fix and bond the two optical fibers together. The main feature of this method is that the connection is fast and reliable, and the typical attenuation of the connection is 0.1~0.3dB/point. However, the long-term use of the connection point will be unstable, and the attenuation will increase greatly, so it can only be used for emergency use in a short time.

3) Active connections:

Active connection is a method of connecting site to site or site to fiber optic cable using various fiber optic connection devices (plugs and sockets). This method is flexible, simple, convenient and reliable, and is mostly used in computer network wiring in buildings. Its typical attenuation is 1dB/connector.

2. Optical fiber detection:

The main purpose of optical fiber inspection is to ensure the quality of system connection, reduce fault factors and find out the fault point of optical fiber. There are many detection methods, mainly divided into manual simple measurement and precision instrument measurement.

1) Manual and simple measurement:

This method is generally used to quickly detect the on-off of optical fibers and to distinguish the fibers made during construction. It uses a simple light source to inject visible light from one end of the optical fiber, and observe which one emits light from the other end. Although this method is simple, it cannot quantitatively measure fiber attenuation and fiber breakpoints.

2) Precision instrument measurement:

Using an optical power meter or an optical time domain reflectometry (OTDR) to quantitatively measure the optical fiber, the attenuation of the optical fiber and the attenuation of the joint can be measured, and even the position of the breakpoint of the optical fiber can be measured. This measurement can be used to quantitatively analyze the causes of fiber optic network failures and evaluate fiber optic network products.