Abstract
Abstract. As BeiDou navigation system has been operational since December 2012. There is an increasing desire to use multiple constellation to improve positioning performance. The signal-in-space (SIS) anomaly caused by the ground control and the space vehicle is one of the major threats to affect the integrity. For a young Global Navigation Satellite System, knowledge about SIS anomalies in history is very important for not only assessing the SIS integrity performance of a constellation but also providing the assumption for ARAIM (Advanced Receiver Autonomous Integrity Monitoring). In this paper, the broadcast ephemerides and the precise ones are pre-processed for avoiding the false anomaly identification. The SIS errors over the period of Mar. 2013-Feb. 2016 are computed by comparing the broadcast ephemerides with the precise ones. The time offsets between GPST (GPS time) and BDT (BeiDou time) are estimated and removed by an improved estimation algorithm. SIS worst-UREs are computed and a RMS criteria are investigated to identify the SIS anomalies. The results show that the probability of BeiDou SIS anomalies is in 10-3 level in last three years. Even though BeiDou SIS integrity performance currently cannot match the GPS integrity performances, the result indicates that BeiDou has a tendency to improve its integrity performance.
Highlights
As BeiDou navigation system has been operational since December 2012
WUM (Multi-Global Navigation Satellite System (GNSS) products of Wuhan University, indicated by WUM) ephemerides published by Wuhan University since the beginning of the year 2013 is the most continuous BeiDou Navigation Satellite System (BDS) precise ephemerides which are postprocessed by PANDA (Positioning And Navigation Data Analyst) software by using the data collected from the BeiDou experimental tracking monitoring stations and some stations of IGS multi-GNSS experiment (MGEX)
2.1.2 Broadcast Ephemerides: BeiDou Broadcast ephemerides from 15 MGEX stations are downloaded because the 15 MGEX stations spread all over the world, BeiDou satellites are seamlessly visualized by the 15 MEGX stations
Summary
BeiDou Navigation Satellite System (BDS) and timing in the service in the Asian-Pacific region since the late 2012. With the modernization of GPS, the fully-operation constellation of GLONASS, and the developing of Galileo system, there is an increasing desire to use the multi-constellation Global Navigation Satellite System (GNSS) to enhance position accuracy, continuity, integrity and availability. For real-time GNSS positioning users, the broadcast navigation message including ephemeris data, are used to calculate the satellite orbits and clock corrections which indicate the time of the constellation. The reason for system completely failure is that bad ephemerides were uploaded to satellites It resulted in position solution was off by more than 50km. For stand-alone ARAIM users, a SIS anomaly could result in the hazardous misleading position solution. The knowledge is expected to broadcast to users in integrity Support Message (ISM) The BDS anomalies over the three year from Mar 1, 2013 to Feb 29, 2016 are presented and discussed
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