改进的大气激光通信PPM调制解调系统设计

摘要

In order to improve the performance of PPM demodulation system, we proposed an improved digital phase⁃locked loop to extract slot synchronization clock and a fast frame synchronization extraction scheme. On the basis of traditional digital phase⁃locked loop, the digital filter and FIFO buffer unit are added. The results show that the slot synchronization clock can be precisely adjusted. The adjustment accuracy is 0.25π. The jitter of slot synchronization clock is only 1.5 ns in 10 Mbps. Finally the system achieves atmospheric laser communication in 10 Mbps.%为进一步提高PPM解调的性能，系统以FPGA为主控单元，提出了一种改进的数字锁相环提取时隙同步时钟和快速帧同步提取方案，在传统的数字锁相环中添加了数字滤波器和FIFO缓存单元．结果表明：系统能够精确地调整时隙时钟，调整精度达到0．25π，10 Mbps信号的时隙时钟的抖动量仅为1．5 ns，最终系统实现了10 Mbps的大气激光通信．