Application scenarios of optical fiber transceiver

一、 What is an optical transceiver

Optical fiber transceiver is an Ethernet transmission media conversion unit that exchanges short-distance twisted pair electrical signals and long-distance optical signals. It is also called fiber converter in many places. The products are generally used in the actual network environment where Ethernet cable cannot cover and optical fiber must be used to extend the transmission distance, and are usually located in the access layer application of broadband man; For example, high-definition video image transmission of monitoring safety engineering, etc.

二、 How do optical fiber transceivers access the network

Because the maximum transmission distance of the network cable (twisted pair) we often use has great limitations, the maximum transmission distance of twisted pair is generally 100 meters. Therefore, when we are arranging a large network, we have to use relay equipment. Of course, other kinds of lines can also be used for transmission. For example, optical fiber is a good choice. The transmission distance of optical fiber is very long. Generally speaking, the transmission distance of single-mode optical fiber is more than 10km, while the maximum transmission distance of multi-mode optical fiber can reach 2km. When using optical fiber, we often use optical fiber transceiver. At this time, the problem arises. How to use the optical fiber transceiver? How does it access the network? As we all know, a network is composed of various optical devices, and optical fiber transceiver is an important part of it. When the optical fiber transceiver is connected to the network, the optical cable should be introduced from the outside first. The optical cable shall be welded in the optical cable box, that is, the terminal box. The welding of optical cable is also a knowledge. You need to peel off the optical cable, weld the fine fiber in the optical cable with the tail fiber, and put it in the box after welding. Pull out the pigtail and connect it to the ODF (a rack connected with a coupler), then connect it to the jumper with a coupler, and finally connect the jumper to the optical fiber transceiver. The next connection sequence is router - switch - Lan - host. In this way, the optical fiber transceiver is connected to the network.

三、 Types and applications of optical fiber transceivers
When the distance between two network devices exceeds the transmission distance of copper cable, optical fiber cable is needed to connect, and optical fiber transceiver is responsible for the conversion between the two media. This kind of optical fiber transceiver can be subdivided into the following categories:

1. Ethernet optical fiber transceiver
This type of optical fiber transceiver can connect devices used for Ethernet, fast Ethernet and 10G Ethernet to realize seamless connection between devices with different rates and different port types. It is usually used for point-to-point transmission conversion, campus transmission conversion, etc. For example, during the conversion of point-to-point transmission, two optical fiber transceivers can be used to connect two UTP (unshielded twisted pair) Ethernet switches, or directly connect the UTP switch to the intelligent terminal.

2. TDM (time division multiplexing) optical fiber transceiver
This kind of optical fiber transceiver mainly includes T1 / E1 and T3 / E3 models. These two kinds of optical fiber transceivers need to be used in pairs. When extending the cable transmission distance, they can play a certain role in avoiding noise, improving service quality and network security. T1 / E1 optical fiber transceiver meets the standards of T1 (1.544mbps) and E1 (2.048mbps). For the installation and maintenance of T1 and E1 connecting lines, this kind of optical fiber transceiver can also play the role of testing and troubleshooting. T3 / E3 optical fiber transceiver complies with T3 (44.736mbps) and E3 (34.368mbps) standards and can be used to connect PBX (private branch exchange), multiplexer, router and other equipment. This kind of optical fiber transceiver can be used for signal transmission between buildings and can expand telecommunications division points.

3. Serial port to optical fiber converter
This kind of optical fiber transceiver is a multifunctional optical fiber modem supporting asynchronous RS-232 and RS-485 communication interfaces. It is the best choice to connect remote terminal unit (RTU) to host or distributed data acquisition system (SCADA) controller. It supports multiple asynchronous communication protocols of RS-232 and RS-485, can mix two RS-232 and RS-485 interfaces at the same time, and supports 2-wire (half duplex) RS-485 working mode. RS-485 optical fiber transceiver supports data (TXD or SD) transmission control, which improves the ability to adapt to various software and simplifies the control mode. Optical fiber modem supports a variety of optical fiber connection modes between asynchronous serial ports. It supports the equipment of two asynchronous serial ports to conduct full duplex or half duplex communication through optical fiber. The communication distance can be up to 4km for multi-mode and 20km for single-mode, The maximum transmission rate of RS-232 signal is 115.2kbps, and the maximum transmission rate of RS-485 signal is 460kbps. Interfaces of different electrical standards can be mixed. RS-232 equipment can be used to connect RS-485 equipment, replace RS-232 to RS-485 interface converter or photoelectric isolator, and provide excellent EMI / RFT (electromagnetic interference / function test) characteristics.