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

Objectives: Integrity monitoring is crucial for ensuring the reliability of real-time precise point positioning (RT-PPP). Traditional studies primarily focus on the user-level integrity monitoring, while the master station is usually employed for the determination of integrity parameters used for the user-level integrity monitoring. This approach places a significant burden of integrity on the user level and requires substantial processing capabilities, failing to fully utilize the role of master station in integrity monitoring. Currently, several analysis centers publicly provide real-time precise satellite orbit and clock correction products. The format protocol of radio technical commission for maritime service (RTCM) has reserved slots for integrity information of the satellite orbit and clock correction products. However, to our knowledge, none of the analysis center has yet publicly provided integrity services for real-time precise satellite orbit and clock correction products. Methods: This contribution constructs a pre- and post-broadcast monitoring architecture for integrity service of real-time precise satellite orbit and clock correction products. The quality indicator is first determined by employing the CDF overbounding approach. Then, a multi-station cooperative monitoring including fault detection and integrity bound evaluation is developed. The quality indicator is assessed to meet the required integrity risk and continuity risk. Finally, the integrity information is encoded in RTCM and broadcast to users via NTRIP. Results: Based on the data stream from the established integrity monitoring network in Shandong Province and the real-time correction products provided by CNES, the integrity services for real-time precise satellite orbit and clock are provided. The performance of the provided integrity services is preliminarily evaluated using the CODE final satellite orbit and orbit correction products as a reference. The experimental results indicate that the availability of integrity monitoring of the real-time precise satellite orbit and clock correction products exceeds 99.99%. Conclusions: The quality indicator provided by the integrity service for real-time precise satellite orbit and clock can effectively characterize the errors of satellite orbit and clock correction products.