一种双星故障条件下RAIM可用性评估的改进方法

在总结已有的RAIM可用性评估的矩阵最大特征值方法（MMEM）基础上，改进已有的双星故障条件下RAIM可用性方法中的数学模型，提出RAIM可用性评估的极大值方法（MM）。基于给定的完好性风险参数和国际GNSS监测评估系统（IGMAS）提供的2020-09-06中国境内8个跟踪站的BDS实测数据，利用2种方法计算双星故障条件下水平保护级别（HPL），比较并分析2种方法在双星故障条件下BDS的RAIM可用性性能。结果表明，在中国境内，MMEM除在非精密进近（NPA）计算的RAIM可用性不及MM外，整体可用性高于MM，但MM耗时较少；MM计算的可用性能够完全满足航路和远洋2个阶段，MMEM计算的可用性可以完全满足终端、航路和远洋3个阶段；基于MM的RAIM可用性评估方法理论严密、数学模型简单、易于进行程序设计，是除MMEM外的另一种RAIM可用性评估方法。

An Improved Method of RAIM Availability Evaluation under Double-Satellite Faults Conditions

Based on summarizing the existing matrix maximum eigenvalue method(MMEM) of RAIM availability evaluation, we improve the mathematical model in the existing RAIM availability method under double-satellite faults conditions, and propose the maxima method(MM) of RAIM availability evaluation. Based on the given integrity risk parameters and the BDS measured data of 8 tracking stations in China provided by the international GNSS monitoring and assessment system(IGMAS) on September 6, 2020, we use the two methods to calculate the horizontal protection level(HPL) under double-satellite faults conditions to compare and analyze the RAIM availability performance of BDS. The results show that the MMEM-based RAIM availability is lower than that of the MM in non-precision approach(NPA) in China, the overall MMEM-based RAIM availability is higher than that of MM, but the MM method consumes less calculation time. The MM-based RAIM availability can fully meet the route and ocean stages, and the MMEM-based RAIM availability can fully meet the terminal, route and ocean stages. The MM-based RAIM availability has rigorous theory, a simple mathematical model, and is easy to program. It is another RAIM availability evaluation method besides MMEM.