基于CMOS跟踪探测器星间光通信系统跟踪及通信性能优化研究

For inter-satellite laser communications, high stability and high precision tracking performance is a prerequisite for reliable communication. The tracking performance is highly depending on the fine tracking subsystem, for which satellite vibration and detector noise are the fatal influence factors. Give consideration of CMOS detector’s outstanding feature of sub-window, which will highly reduce the complexity of optical communication terminal, the following works will be researched in this project. First, the optimum FTSW of CMOS in single FPAD system was studied in the presence of satellite platform vibration. In the focal plane, the random jitter model of received beam spot is established. And the equations about optimum FTSW size are presented. Secondly, the influence of CMOS detector error on system tracking error and the stability of bi-directional closed tracking loop are investigated. The relation between system tracking error and CMOS detector error was analyzed. The interaction relation between the two optical terminals’ tracking error is modeled. The stability of bi-directional tracking was studied in case of identical tracking sub-systems. Finally, the channel capacity and outage probability is investigated with respect to CMOS parameters. What achieved in this dissertation contributes to the theory of tracking and communication for intersatellite laser communications, and can benefit the optimization of intersatellite laser communication systems.

星间光通信中，高稳定、高精度的跟踪是星间激光链路可靠通信的前提和保障。星间激光链路的跟踪精度以及跟踪稳定性是由精跟踪子系统最终决定的。对于精跟踪子系统来说，卫星平台振动和精跟踪探测器噪声是影响链路跟踪性能的主要因素。考虑到CMOS可开子窗口的特性将大大降低光通信终端的复杂度，本项目针对基于CMOS探测器的星间光通信系统：建立平台振动条件下焦平面探测器上接收光斑的随机抖动模型，给出CMOS探测器精跟踪子窗口优化设计的约束方程；分析单向跟踪时CMOS探测器误差与系统跟踪误差的影响关系，基于此分析得到双向闭环跟踪时两个光终端上跟踪误差的相互制约关系模型，给出链路跟踪稳态存在、跟踪误差角方差收敛、以及稳态跟踪误差角方差等对CMOS探测器参数的依赖关系；基于稳态跟踪方差得到其对链路通信性能的影响规律；地面模拟实验的验证。本项目的完成将为星间激光链路跟踪性能的优化设计提供重要的理论依据。

卫星激光通信被誉为新一代的空间通信技术，具有数据率高、通信容量大的独特优势，是满足现代社会对信息快速、实时传输需求的最佳途径。星间高速激光通信链路作为未来太空信息高速公路的骨干链路，是实现未来天地一体化高速实时光通信网络的关键，具有重要的经济和战略地位。. 本项目对单CMOS探测器星间激光通信系统中精跟踪子窗口的优化问题进行了理论和实验研究，并探讨了CMOS探测器误差对跟踪性能尤其是双向闭环跟踪稳定性的影响，最后从理论上分析了随机跟瞄误差角抖动对星间激光通信中信道容量和错误概率的影响。具体内容包括以下几个方面：.1. 对卫星平台振动条件下单CMOS探测器星间激光通信系统中精跟踪子窗口优化问题进行了研究。在焦平面阵列探测器上，建立了卫星平台振动条件下接收光斑随机抖动的统计模型；基于该模型，得到了CMOS探测器上最佳精跟踪子窗口的约束方程；以OLYMPUS卫星平台振动特性为例，对最佳精跟踪子窗口的优化进行了数值仿真。最后，进行了平台振动对接收光斑随机抖动特性影响的模拟实验，验证了理论分析的正确性。.2. 研究了CMOS探测器测角误差对系统跟踪精度以及双向闭环跟踪稳定性的影响。分析了单向跟踪时系统跟踪误差与CMOS探测器误差之间的关系，建立了双向闭环跟踪时两个光终端上跟踪误差角方差的相互制约关系模型；重点对两光终端跟踪子系统全同条件下双向闭环跟踪链路的稳态问题进行了研究，给出了稳态存在、跟踪误差角方差收敛、以及稳态跟踪误差角方差等对CMOS探测器参数的依赖关系。.3. 针对OOK通信系统，研究了随机跟瞄误差角抖动对星间激光链路的通信能力和信息传输的可靠性的影响，建立了随机跟瞄误差角抖动下星间激光链路的传输矩阵，给出了最大信息传输率时的最佳输入概率；研究了最佳输入概率和信道容量随系统各参量的变化规律。建立了随机跟瞄误差角抖动下星间激光链路的错误概率模型，给出了错误概率最小时的最佳束散角；在最佳束散角条件下讨论了其它系统参量对错误概率的影响。.本项目的研究工作进一步完善了星间激光通信中关于跟踪、通信的理论研究，为星间激光通信系统的优化设计提供了理论依据。