Real-time quality indicator determination for precise satellite orbit and clock corrections from integrity perspective
摘要
The integrity of real-time precise satellite orbit and clock corrections is indispensable due to their significant impact on the reliability of precise point positioning (PPP) solutions. To leverage PPP for safety–critical navigational applications, the quality indicator for the satellite corrections provided to PPP users is generated through the integrity monitoring among the ground monitoring stations (GMSs) network to protect against the multiple faults from the satellite corrections and GMS, simultaneously. This contribution proposes a residual-based quality indicator computation, evaluation, and adjustment method from integrity perspective. By overbounding the instantaneous user range error (IURE), the initial quality indicator of the satellite corrections is first computed in offline mode. Then, in order to control the effect of multiple faults on the integrity of satellite corrections, the initial quality indicator is evaluated based on cooperative monitoring (COM) among multiple GMSs. Finally, an integrity-constrained adjustment strategy for the quality indicator is constructed through iterative search to simultaneously satisfy the required integrity and continuity. The experiments using one year of real-world data have shown that the proposed method effectively guarantees the integrity of the satellite corrections under both the fault-free and the fault cases. The user-side integrity monitoring can achieve an availability improvement of 21.53% by utilizing the proposed quality indicator.