基于码减载波和B值的GBAS精度性能分析

Performance analysis of GBAS based on code minus carrier and B values

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 paper assessed GBAS accuracy performance based on two methods. A GBAS prototype was developed and used to collect and process GPS data. Based on the raw data, two methods called CMC and B values were used to analysis to GBAS accuracy performance. The result of both methods showed consistently that the GBAS prototype accuracy was on the level of GAD-A2 class. Compared with each other, CMC needs to use observations of dual frequencies, however, B values rely on single frequency. Secondly, CMC suppressed short-term muhipath errors, and long-term muhipath effects remained. B values, however, mainly consist of composite effects of multiple receivers＇ errors after averaging across reference receivers, which reflect realistic errors of GBAS corrections as both occupied similar processes. Lastly, sky-maps of root mean squares of CMC and B values reflected surrounding muhipath effects of GBAS sites.