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Basic knowledge about fiber optic transceivers
Knowledge Base + 2024.01.05

1.1 Basic function module

The optical fiber transceiver includes three basic functional modules: photoelectric media conversion chip, optical signal interface (optical transceiver integrated module) and electrical signal interface (RJ45). If equipped with network management functions, it also includes a network management information processing unit.

fiber optic 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 a photoelectric converter (Fiber Converter) in many places. The product is generally used in the actual network environment where the Ethernet cable cannot cover and the optical fiber must be used to extend the transmission distance, and is usually positioned in the access layer application of the broadband metropolitan area network; at the same time, it helps to connect the last mile of the optical fiber line to the metropolitan area The Internet and the outer network also played a huge role.

In some large-scale enterprises, optical fiber is used as the transmission medium to establish a backbone network during network construction, while the transmission medium of the internal LAN is generally copper wire. How to realize the connection between the LAN and the optical fiber backbone network? This requires conversion between different ports, different lines, and different optical fibers and guarantees the quality of the link. The emergence of optical fiber transceivers converts the electrical and optical signals of the twisted pair to each other, ensuring the smooth transmission of data packets between the two networks, and at the same time, it extends the transmission distance limit of the network from 100 meters of copper wires to more than 100 kilometers ( Single-mode fiber).

1.2 Basic characteristics of fiber optic transceivers

1. Fully transparent to the network protocol.

2. Provide ultra-low latency data transmission.

3. Support an ultra-wide operating temperature range.

4. Use a dedicated ASIC chip to realize data line-speed forwarding. Programmable ASIC concentrates multiple functions on one chip, and has the advantages of simple design, high reliability, and low power consumption, which can enable equipment to obtain higher performance and lower cost.

5. The network management equipment can provide network diagnosis, upgrade, status report, abnormal situation report and control functions, and can provide a complete operation log and alarm log.

6. Rack-type equipment can provide hot-swappable function for easy maintenance and uninterrupted upgrades.

7. Support complete transmission distance (0~120km).

8. Most equipment adopts 1+1 power supply design, supports ultra-wide power supply voltage, and realizes power supply protection and automatic switching. 

1.3 Classification of fiber optic transceivers

There are many types of fiber optic transceivers, and their types change accordingly according to different classification methods.

According to the nature of the fiber, it can be divided into multi-mode fiber transceiver and single-mode fiber transceiver. Due to the different optical fibers used, the transmission distance of the transceiver is different. The general transmission distance of multi-mode transceivers is between 2 kilometers and 5 kilometers, while the coverage of single-mode transceivers can range from 20 kilometers to 120 kilometers;

According to the required optical fiber, it can be divided into single-fiber optical fiber transceiver: the data sent and received are transmitted on one optical fiber; the dual-fiber optical fiber transceiver: the data received and sent is transmitted on a pair of optical fibers.

According to the working level/rate, it can be divided into single 10M, 100M fiber optic transceivers, 10/100M adaptive fiber optic transceivers and 1000M fiber optic transceivers. According to the structure, it can be divided into desktop (stand-alone) fiber optic transceivers and rack-mounted fiber optic transceivers. The desktop optical fiber transceiver is suitable for a single user, such as meeting the uplink of a single switch in the corridor. Rack-mounted (modular) fiber optic transceivers are suitable for the aggregation of multiple users. For example, the central computer room of a community must meet the uplink of all switches in the community.

zccording to network management, it can be divided into network management type optical fiber transceiver and non-network management type optical fiber transceiver.

According to the management type, it can be divided into non-network management Ethernet fiber optic transceivers: plug and play, set the working mode of the electrical port through the hardware dial switch. Network management type Ethernet fiber optic transceiver: support carrier-grade network management

According to the type of power supply, it can be divided into built-in power fiber optic transceivers: built-in switching power supplies are carrier-grade power supplies; external power fiber optic transceivers: external transformer power supplies are mostly used in civilian equipment. The advantage of the former is that it can support an ultra-wide power supply voltage, better realize voltage stabilization, filtering and equipment power protection, and reduce external failure points caused by mechanical contact; the advantage of the latter is that the equipment is small in size and cheap.

Divided by the working mode, the full duplex mode (full duplex) means that when the sending and receiving of data are split by two different transmission lines, both parties in the communication can send and receive at the same time. This kind of transmission The mode is full-duplex, and the full-duplex mode does not need to switch the direction, so there is no time delay caused by the switching operation;

Half duplex refers to the use of the same transmission line for both receiving and sending. Although data can be transmitted in two directions, both parties in communication cannot send and receive data at the same time. This transmission method is half-duplex.

When the half-duplex mode is adopted, the transmitter and receiver at each end of the communication system are transferred to the communication line through the receiving/sending switch to switch the direction. Therefore, time delay will occur.