Two major bottlenecks of optical transceivers and methods for their stability

With the impact of IP, the network transmission method of the TCP/IP protocol is also increasingly applied, but security video surveillance still uses the coaxial cable as the transmission medium for the short-distance signal transmission and reception. However, no matter which transmission method, it can not meet the transmission needs of modern security. Optical terminal as a transmission medium terminal equipment, it becomes important in the entire transmission.

Simple analysis of the two major bottlenecks of optical transceivers Although optical transceivers have been developed more mature, but this is not to say that it has reached the pinnacle of technology and applications, but relative to the current level of technology, the products developed by manufacturers have basically approached the theoretical height of the current technology It has been difficult to seek major technical breakthroughs, but there are still some technical bottlenecks, mainly reflected in the following aspects.

•Compatibility. For the sake of protecting the self-interest, manufacturers have differentiating their own products under a large framework. Although the optical transceivers only transmit the equipment, if they are not compatible with the products, there is no way to transfer the products. Liu Xueming, Weidi digital system, said: "Technically, compatibility is not difficult, as long as manufacturers open their own agreements on project cooperation can achieve system compatibility. But now all manufacturers set their own analog, digital conversion and transmission protocols and standards Not all the same, if you do not open the agreement, Guangduan does not have the ability to achieve compatibility with other manufacturers.” He also pointed out that the non-standardization of industry agreements will likely guide the future monitoring industry to broadcast standards that will not lead to the inconsistency of the standard international standards SDI technology development;

• In the impact of network transmission, Shi Zhijun, Manager of Technical Support Department of Wuhan Micro Optoelectronics Co., Ltd., introduced to the author that the development of IP surveillance will bring two diametrically opposite effects to optical transceivers: One view is that the transmission speed is not due to network bandwidth limitations. Stability, and the increase in the compression transmission technology of the optical transceivers will enable the two to develop in the future rather than in competition. Therefore, the optical transceiver market based on optical fiber transmission will not be affected. However, another view is that with the acceleration of the IP process, the proportion of video optical transceivers in the entire security monitoring system is shrinking. The emergence of this view is indeed groundless, the application of Gigabit Ethernet and the flexibility of network transmission, etc. All must be better than optical fiber transmission. If the limit of the transmission distance can be exceeded, replacing the optical transmission method will become a reality, which brings great challenges to optical transmission applications.

At this stage, although there are still some technical difficulties in the optical transceiver, its advantage is that other technologies cannot replace it. Video optical transceivers are focusing on the improvement of equipment network management, multi-service, and reliability, and will continue to exist as the main force of transmission for a long time in the future.

The so-called all roads in Rome, light transmission is only one of many transmission methods, other transmission methods are not worse than light transmission, but they have their own advantages and disadvantages, development is endless, through technological breakthroughs, other technologies can also reach or exceed light The level of transmission, therefore, we also look forward to the emergence of more mature transmission technologies or complementary applications of various transmission technologies in the future, for the benefit of security and for the benefit of mankind.

Opto-Electronics has four major advantages: The maturity of the optical transceiver technology has caused many manufacturers to struggle in the field of research. Prior to the breakthrough in technology, the company focused on the development of product performance, and strived to achieve breakthroughs in product quality. At the same time, it also targeted the market. Need to add some new applications to meet the individual needs of customers. At present, manufacturers mainly improve the optical transceivers from the following points.

1, the development of the main single-mode fiber by light in which the transmission can be divided into multi-mode and single-mode. Multi-mode fiber allows different modes of light to be transmitted over a single fiber. Its core diameter is 50 μm or 62.5 μm. When it is transmitted on a local area network, many optical power paths are often detoured due to detours, resulting in large optical signal transmission loss. The advantages of multi-mode fiber, such as relatively low transmission rate, relatively short transmission distance, multiple nodes, multiple joints, multiple detours, large amount of connectors/couplers, small size, and a large number of light sources per unit fiber length, are exerted. From the perspective of the development of the industry, the advantages of multi-mode is also its shortcomings, unable to meet the needs of long-distance transmission. While the center glass core diameter of a single-mode fiber is about 9 μm, although only one mode of light can be transmitted, the mode dispersion is small. Especially at a wavelength of 1.31 μm, the material dispersion and waveguide dispersion of a single mode fiber are positive. One is negative, the size is exactly the same, can completely avoid the modal dispersion, making it an ideal work window for optical fiber communication, and the transmission effect is good, not easily affected by interference, transmission frequency bandwidth, transmission capacity, adapt to large capacity, far From the optical fiber transmission, therefore, the single-mode transmission has become an inevitable trend in the future of optical fiber communication and technology development. Of course, high performance and high technical requirements, especially for the requirements of the light source body, still need to stabilize.

2. Modular design and hybrid access optical transceivers are used as the transmission medium. It presents the status of passive development. Only if other fields change, will it be forced to follow up. The industry has different development in different periods and product updates. The replacement speed can not keep up, resulting in the coexistence of multi-times products, how to make full use of the existing optical transceiver resources in a variety of products in the era? Tiandi Weiye Digital Technology Co., Ltd. Optical Terminal Product Manager Li Tianyou proposed a set of solutions specifically for this status quo : There are many types of optical transceivers, and the field applications are also different. Modular design of optical transceivers can greatly enhance the flexibility of optical transceiver configuration. Different modules can be used according to customers' different needs. It is flexible and convenient; The use of optical transceiver products, changes in function or increase, directly replace the different functional modules can be, for the user to save the time and cost of the replacement machine. The advantages of modular design are obvious, such as the application of multi-mode transmission, multi-mode optical devices have basically been discontinued, and some users are still using this method, through the internal configuration of a single, multi-mode adaptive circuit optical transceiver, you can Directly use single-mode optical transceivers to complete multi-mode transmission applications. Due to the flexibility of modular design, it can also provide scalable application for system development, which facilitates the increase of system access or application functions in the later period.

In the face of complex product status, hybrid access designs can be used in addition to modular designs. Digitalization has become an irreversible reality. Currently, the number of new products introduced by the manufacturers has become lower and the proportion of analog products has become lower and the number of network products has increased exponentially. This has been accompanied by the integration of broadcast-grade SDI technology and the coexistence of different standard products. The application has brought a lot of inconvenience, so there are manufacturers to improve the compatibility of optical transceivers, provided in the device optical port, RJ-45 network interface, BNC interface, VGA / DVI / HDMI interface, so that in the same Optical transceivers can transmit analog signals as well as access networks, digital signals, high-definition signals, and so on. In terms of service volume, they have also greatly improved. “In addition to accessing video, it can also support low-speed asynchronous data, audio, and Ethernet. Network, switch, telephone, E1 and other signals; In addition to the transmission of normal services, Optical has also added many features, such as ambient temperature detection, remote power-off alarm, character overlay (OSD), interface three lightning protection, SNMP network management, etc.” Yao Zhihong, chief technology officer of Beijing Lvshi Communication Technology Co., Ltd., introduced.

3. Enhancing the operation and maintenance of the system The transmitters and receivers of the optical transceivers are used in pairs. The distance between the two transmitters is far away and the installation environment is different. They are often placed in remote and environmentally unfriendly areas such as petroleum and petrochemical and highways, and the maintenance is inconvenient. Once the unfavorable circumstances such as the disconnection of the transmission channel will cause problems for the application, Liu Xueming, general manager of Chengdu Micro Digital System Technology Co., Ltd. pointed out that there are still many products in the industry that are not doing well enough to maintain stability. Generally, the manufacturer will maintain the application stability of the optical transceiver system from the following two aspects.

·Adaptive harsh environment, this function is designed to make the product have a stronger adaptability to the environment, can play system self-protection under the lightning and other damage. The practices of different manufacturers are slightly different, but nothing but the ultimate goal of protecting the hardware. Take Tiandi Weiye as an example, their products have accumulated and transformed through many years of experience. At present, a set of mature methods has been formed, namely, three kinds of protection circuits are built in the system: three levels of communication interface protection, to achieve lightning discharge, over Stream automatic recovery function; composite video protection level up to 75V (2V no-load amplitude, 1V with 75Ω load), can protect to more than 30 times the normal video signal; two-stage power protection, overvoltage TVS protection and Overflow self-healing insurance. So as to achieve the purpose of ensuring the stable operation of the equipment in a more harsh field environment;

Self-diagnosis technology, also called fault early warning function and network management function, is particularly important in the application of optical platforms. It is an important advancement in the development of optical terminals to intelligent devices. Through the system's self-diagnosis function, the loopholes and defects in intelligent discovery systems can be realized. So that the system can be quickly remedied. Beijing Guangqiao Technology Co., Ltd. engineer Kong Xiangkai introduced: "The fault early warning function is mainly through reading the information of various functional modules, power supply parameters, etc., and then display the parameters, when these parameters reach a certain limit value, The system will send out an aging alarm.The traditional video optical transceiver can only provide a fault prompt after a fault occurs, but the fault early warning function can be used to warn in advance, and the diagnostic system can perform real-time health diagnosis of the optical transceiver system, including the optical transceiver and the connected optical transceiver. The real-time monitoring of the optical fiber can monitor and maintain the working status of the equipment in real time. If there is a fault, the equipment can be repaired in advance so that it can be prevented.

4. Abundant application forms At present, although the application of optical transceivers is diversified, there are also many restrictions, and arbitrary topology access has not formed a good solution. Liu Xueming, Chengdu Micro Digital System, points out: “Original optical transceivers are divided into several major series, such as Point-to-point, node, ring, convergence, and other product lines, each series will be divided into many specifications, which brings many problems to the application. "Although different access technologies can meet different needs, but the access requirements are complex The system is difficult to solve, for example, peer-to-peer cannot be cascaded, nodes cannot be aggregated, and aggregation can not be nodes. Access technology is still plaguing many manufacturers. In the process of solving this problem, MicroDi has proposed a solution for Anyaccesx technology. The application of this technology will greatly reduce the product to one or two specifications, and customers can connect randomly. In the light of the convenience of planning according to the condition of the fiber access point, the optical transceiver will not be subject to point-to-point, node, ring, convergence, etc., and a product that is compatible with all access methods, while surpassing the original access technology It can greatly reduce the number of fibers used, and it also reduces the difficulty for customers to plan the routing of fiber access, which saves resources and provides convenience for applications.