Real-Time Monitoring for BDS Signal-In-Space Anomalies Using Ground Observation Data.

Haitao Wang,Zemin Wang,Hu Jiang,Yunbin Yuan

doi:10.3390/s18061816

Abstract

Signal-in-space (SIS) User Range Error (URE) is one of the major error sources for BeiDou Navigation Satellite System (BDS) applications and can reach tens of meters or even more. Therefore, real-time monitoring of SIS anomalies has a great realistic significance to guarantee the safety of users. According to an analysis of the BDS navigation messages, it showed that the User Range Accuracy (URA) index could not reflect the change of URE when it was abnormal. The conventional models using the relationship between URA and URE to monitor SIS anomalies are not suitable to the present BDS. Therefore, we use a prior information of SIS URE derived from ground observational data instead of URA to monitor BDS SIS anomalies. In order to realize the corresponding functions, we analysed the distribution of SIS UREs and obtained their prior models. Then, the monitoring threshold is determined using the prior models and a confidence interval instead of URA. The scheme was tested by applying to BDS SIS anomalies monitoring based on 13 ground tracking stations. The performance of this method was assessed by comparison with the satellite-health indicators from broadcast ephemeris. The results confirm that the method developed in this paper can rightly and timely detect abnormal SIS.

Highlights

The BeiDou Navigation Satellite System (BDS) was officially put into operation on 27 December2012 and can overlap the Earth surface in 2020 s [1]
Errors arise primarily from imperfect estimation of a satellite orbit and clock error and are usually undetectable and uncorrectable for stand-alone open service (OS) users [5]. It is mainly described by the parameter of User Range Error (URE) that is the pseudorange inaccuracy attributable to the ground control and space vehicles and the one of major error sources affecting Global Navigation Satellite System (GNSS)
Anomalies are monitored on the basis of the relationship between SIS UREs and User Range Accuracy (URA) as follows: if the SIS UREs are greater than 4.42 × URAUB, it can be determined that the satellite service is not Sensors 2018, 18,[12]

Summary

Introduction

The BeiDou Navigation Satellite System (BDS) was officially put into operation on 27 December2012 and can overlap the Earth surface in 2020 s [1]. The BeiDou Navigation Satellite System (BDS) was officially put into operation on 27 December. For most BDS OS users, real-time satellite orbits and clocks are derived from predicted ephemeris and clock parameters in navigation messages broadcast by BDS satellites. Errors arise primarily from imperfect estimation of a satellite orbit and clock error and are usually undetectable and uncorrectable for stand-alone OS users [5]. It is mainly described by the parameter of User Range Error (URE) that is the pseudorange inaccuracy attributable to the ground control and space vehicles and the one of major error sources affecting Global Navigation Satellite System (GNSS)

Methods

Discussion

Conclusion