对GBAS精度性能进行了分析。分别按照基于码减载波(code minus carrier,CMC)和B值两种方法对GBAS基准站实际数据进行了分析。CMC分析结果和B值的分析结果一致表明,GBAS基准站的精度性能等级约为GAD-A2。CMC分析法与B值分析方法具有一些不同的特点。CMC需要使用双频观测量;B值只需要单频观测量。CMC消除了短周期的多路径效应,主要反映的是长周期的多路径效应;B值经过GBAS基准站接收机平均,反映了不同接收机组合的多路径综合效应,更能反映GBAS差分校正误差的实际影响。除此之外,CMC分析法与B值分析法的天空图可以直观地评估GBAS站址的多路径环境。
The high level of safety demand of civil aviation requests local area augmentation system (LAAS) extremely high navigation integrity performance. A new LAAS pseudo-range error overbound method is proposed in this paper to improve the integrity of LAAS. Firstly, a more practical pseudo-range error distribution model is established. Then, by calculating the relationship between the statistical uncertainty of the model parameter and the integrity risk, a new method is proposed to calculate the pseudo-range error over-bound model. This method can effectively reduce the inflation factor and the resulting conservativeness of the over-bound model. Comparative experiments show that the method proposed in this paper performs better and satisfies the requirements of real applications.
