双频双星座地基增强系统精度和完好性算法

针对单频单星座地基增强系统（GBAS）无法满足飞机III类精密进近与着陆导航性能需求的问题，提出了将北斗导航卫星系统（BDS）与全球定位系统（GPS）进行融合，构建一种新型的基于GPS/BDS的双频双星座GBAS。首先，分析了GBAS的工作原理，并对Hatch滤波器的误差进行了分析，给出了一种适用于双频GBAS的无码载偏离载波相位平滑伪距算法；然后，对机载完好性算法进行了研究，给出了H0和H1假设下的机载保护级计算方法；最后，进行了系统验证实验，实验结果表明，单星座GBAS不能满足飞机III类精密进近与着陆导航的性能需求，GPS和BDS融合后可见卫星个数得到提升，优化了卫星几何分布，进而使得系统的可用性由80.6081%提升到大于99.9999%。

Performance Evaluation and Integrity Algorithm of Dual-frequency Dual-constellation Ground Based Augmentation System

Aiming at the problem that single-frequency single-constellation GBAS cannot meet the performance requirements of category III precision approach and landing navigation, by integrating BDS and GPS, a new dual-frequency dual-constellation GBAS based on GPS and BDS is proposed. Firstly, the operating principle of GBAS is analyzed, and the error of Hatch filter is analyzed systematically. A carrier phase smoothing pseudorange algorithm with divergence-free for dual-frequency GBAS is also presented. Then, the airborne integrity algorithm is studied, and the calculation method of airborne protection level under H0 and H1 assumptions is given. Finally, the system verification experiment is carried out, and the results show that the single-constellation GBAS cannot meet the performance requirements of category III precision approach and landing navigation. After GPS and BDS are integrated, the number of visible satellites is increased. So, the geometric distribution of satellites is optimized, and then the availability of the GBAS is improved from 80.6081% to greater than 99.9999%.