OC-48 Multi-Service Optical Transport System Research

With the social progress, science and technology development and improvement of the living standard of the people, the media information is not limited to the video and audio, but the high degree convergence of video, audio, control data and network. Traditional communication media could not satisfy the requirement of mass data transmission. Fiber is widely used with unrivaled advantage. But the function of the present optical transmission system is relatively single. The optical transmission systems of network and video,audio independently occupy the fiber.It not only wastes the fiber resource but also makes the management inconvenient.As result, the comprehensive optical transmission products go to market soon with actual demand.At present, high capacity comprehensive optical transmission products use coarse WDM (CWDM) technology.The fiber is divided into several wavelengths. Different wavelength transports different information. Therefore, the cost of the CWDM device is relatively high. With the Mature of high logic devices and the technology of TDM, it supports the comprehensive optical transmission products which can transport more information in least fiber channel.This paper uses this technology to design a comprehensive optical transmission product which can transport 16 video,8 audio,8 control data and 1 network using single fiber. The design has two channels, and every channel occupies one wavelength. The rate of positively direction channel is high as 2.5Gbps (OC-48).The WDM device is placed in the optical transceiver.The design of low cost and high integration is realized.At first, the paper describes the optical communication and the development and application of optical transceiver.Then, the paper simply analysis the technology of TDM, CWDM,coding and decoding,and PLL used in the system.Then after,the paper detailed describes the design of whole system. Whole system is divided into two parts, one is the hardware design, the other is the software design. The hardware design mainly describes the module of interface,FPGA, serial to parallel converter/parallel to serial converter, optical device and the design of PCB. It uses the DDR technology in video DA\AD module to reduce the data bus and save cost of FPGA.The software design is the key part of the paper.It includes designs of multiplexing and de-multiplexing, failure detecting and alarm video coding.Application of alarm video coding in the optical transceiver is the innovation. According to the characteristics of the composite video signal, automatically generating different video by FPGA when there is no video signal input and fiber failure.The work of the system debugging and failure detecting becomes easy. This design is widely applied to the domain of the highway, the city transport, security, the customs, etc.Through the contrast of the practical test, the key Indicators in the paper are basically same with the optical transceiver that is designed by using CWDM technology, but the integration is high, the function is powerful and the costs significantly reduce.