Integrity Monitoring for Real-time Orbit Corrections based on Prior Statistic Parameters

Real-time precise point positioning relies on the use of accurate satellite orbit corrections for users to provide decimeter to centimeterlevel positioning with a stand-alone receiver. The faults from the satellite orbit corrections must be detected through integrity monitoring in order to provide a reliable corrections service, which becomes more important for safety-critical applications. In this contribution, an integrity monitoring method for real-time orbit corrections based on the priori statistic parameters. Based on the influence of the orbit correction variations on the satellite orbit error, the extrapolation formula of the orbit correction parameters is established at first. Then the detection statistic is constructed based on the difference between the satellite precision orbit corrected by the predicted orbit correction parameters and the precision orbit corrected by the real-time correction parameters. Moreover, the minimum detectable error under the fault mode is calculated based on the noncentralized chi-square characteristics of detection statistics and missed detection rate. The 180-day prior orbit correction data are used to test the false alarm and missed detection performance of the proposed method. The results confirm that the abnormal orbit corrections can be detected accurately and effectively with missed detection rate 1×10-3 , and false alarm rate 1×10-5 . Considering the integrity monitoring for orbit corrections, the PPP results in the north, east and up directions can be improved by 1.4%, 11.0% and 12.8%, respectively. The proposed method can be used to check the satellite orbit corrections before broadcasting, which is helpful to improve the reliability of real-time service.