Threat of Ionosphere Anomaly for GBAS and Its Monitoring Method

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.