Preliminary Performance Evaluation of Integrity Service for Real-Time Precise Satellite Orbit and Clock

Objectives Integrity monitoring is essential for ensuring the reliability of real-time precise point positioning. Traditional studies mainly focus on user-level integrity monitoring, whereas the master station is primarily responsible for determining the integrity parameters required for user-level integrity monitoring. This approach places a substantial integrity-monitoring burden on users and requires considerable computational resources, thereby failing to fully exploit the role of the master station in integrity monitoring. Currently, several analysis centers publicly provide real-time precise satellite orbit and clock correction products. The standard defined by radio technical commission for maritime services (RTCM) has reserved message fields for broadcasting the integrity information of satellite orbit and clock correction products. However, to the best of our knowledge, no analysis center currently provides public integrity services for real-time precise satellite orbit and clock correction products.

Methods This paper develops a pre- and post-broadcast integrity monitoring architecture for real-time precise satellite orbit and clock correction products. First, a quality indicator is determined using the cumulative distribution function overbounding approach. Then, a multi-station cooperative monitoring strategy, including fault detection and integrity bound evaluation, is developed. The quality indicator is evaluated to ensure compliance with the required integrity and continuity risk requirements. Finally, the integrity information is encoded into RTCM messages and broadcast to users through networked transport of RTCM via internet protocol.

Results Based on the data stream from the integrity monitoring network established in Shandong Province and the real-time correction products provided by Centre National d'Études Spatiales, integrity services for real-time precise satellite orbit and clock correction products are generated. The performance of the proposed integrity service is preliminarily evaluated using the final satellite orbit and clock products provided by Center for Orbit Determination in Europe as the reference. The experimental results show that the availability of integrity monitoring for real-time precise satellite orbit and clock correction products exceeds 99.99%.

Conclusions The quality indicator provided by the proposed integrity service can effectively characterize the errors in real-time precise satellite orbit and clock correction products.