The Implement Of PMD Dynamic Compensation Based On FPGA And Nios II Embedded System

As the increase of the optical transmission speed, the problem of pulse broadening caused by Polarization Mode Dispersion (PMD) will be more and more serious. In order to compensate the PMD influence, several years theory research had been taken in our laboratory. On the bases of the research, the forward feedback dynamic compensation scheme was adopted in our project, implementing the dynamic PMD compensation. My job is mainly concerned with the research, the design and the implement of circuit for compensation control. Specifically speaking:1. The proposal of the hardware design with FPGA as the control centre, the selection of IC, the circuit schematic design, the layout and fitting on PCB, the jointing of IC and components. All of these provided a hardware build-up for the whole circuit control.2. In FPGA, some PMD theory values were fast computed by Verilog HDL programing with the pipelining technology. The Nios II Embedded soft CPU was constructed in FPGA and efficient dynamic compensation algorithm was put forward by C language.3. Three dimension coordinate system turning transforming theory was proposed and the related formula was deduced, which promoted the effective control for Polarization controller (PC)The advantages of our project: PMD dynamic compensation was implemented with high speed. The project was independent of transmission speed. That is, the project can work successfully at whatever transmission speed.The disadvantage of our project: We haven't found an effective way from theory for the judgement between fast-axis and slow-axis of transmission line.Concerning the disadvantage, we put forward another scheme which was the integration of the forward feedback system and backward feedback system. That is, a backward feedback mechanism was considered on the basis of our current project.