基于t检验的星基增强系统完好性数据核验

Satellite-based Augmentation System(SBAS) Integrity Monitoring Based on t-test Method

针对星基增强系统(SBAS)高完好性的服务需求,提出了一种SBAS广播参数用户差分伪距误差(UDRE)的完好性核验方法。利用监测站实测全球定位系统(GPS)和地球静止轨道(GEO)卫星信号,解析GPS电文和SBAS广播差分及完好性信息,对观测量修正误差得到实测UDRE,使用t检验成对二样本分析法验证给定置信区间内广播UDRE'与实测UDRE的符合性,从而完成伪距域完好性参数UDRE的核验。伪距域的核验避免了以往位置域核验计算量大、多卫星故障检测能力差的缺点,有更好的故障检测与隔离能力。采集日本多功能GPS卫星星基增强系统(MSAS)数据并对提出的t检验方法进行验证,结果表明,所建立的统计检测量能有效地反应被监测卫星广播UDRE参数的完好性,通过确定卫星99.9%置信度下的判决门限,对广播UDRE与实测UDRE判别,验证伪距误差的可信度。该结果验证了所提方法应用于UDRE核验的可行性,为SBAS完好性验证提供了技术支撑。

According to the integrity requirement of the satellite-based augmentation system（ SBAS）,a method is presented for checking user differential range error（ UDRE） broadcasted by SBAS. After the range measurement is processed by using global positioning system（ GPS） ephemeris and SBAS differential message reference station,true UDRE is obtained and broadcast UDRE＇ is checked in range domain with t-test method. The shortcomings of position domain checking such as enormous computation power and limited statistical fault detection capability are avoided by range domain checking. Results of collecting Japan＇s Multifunctional Satellite Augmentation System（ MSAS） data to verify the proposed method show the established statistical detection can effectively indicate the availability of the monitoring satellite under a threshold of 99. 9% availability.Through comparing the broadcast UDRE with the true UDRE,the credibility of the pseudorange errors is proved. The method is feasible for UDRE monitoring and provides a reference for SBAS integrity verification.