局部电离层异常对局域增强系统的影响及其监测方法
Threat of Ionosphere Anomaly for GBAS and Its Monitoring Method
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摘要: 传统的局域增强系统认为影响用户和基准站伪距的观测误差是基本相同的,因而可通过伪距差分技术将这部分误差消除,但为发生电离层风暴时,叠加在基准站和用户伪距上的电离层延迟误差将会不同,因此会影响定位结果。本文利用CCDMA算法和DSCMA算法对电离层异常进行探测,并对伪距差分技术进行改进。仿真结果显示,这种方法可有效减小局部电离层异常对CATⅢ飞行阶段的威胁。Abstract: GBAS is based on the errors that the errors on the pseudoranges observed by user and reference station is similar.Hence,so the correction provided by reference station is used to revise the pseudorange observed by the user.But when ionosphere anomaly is met,the errors between the the station and user is different and the positioning solution is effected.This paper provides CCDMA and DSCMA algorithms to detect the ionosphere anomaly,and improves the differential positioning solutions of GBAS.The simulation indicate that the algorithm proposed in the paper mitigrates the threat for GBAS and suports CAT Ⅱ-Ⅲ.
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