GNSS Health and Operational Status Tracking

To ensure trustworthiness of PULSAR and other GNSS signals, ground-based monitoring is critical. This identifies and communicates signal faults to end users in a timely manner to ensure high integrity and high precision PNT through Precise Point Positioning (PPP). As receivers rely on a wide variety of signals, some of which do not have any guarantees from their operators, a single source of truth is critical to ensuring signal quality available to users in real-time with low latency time to alert. The proposed Direct-to-Phase II (D2P2) effort will demonstrate Xona’s approach to ground-based GNSS monitoring which includes the extensibility of the system to monitor future GNSS systems such as PULSAR. This project proposes demonstration of a comprehensive GNSS Monitoring System capable of monitoring current and future GNSS systems. This Monitoring System provides a stream of real-time health information for GNSS constellations such as GPS, Galileo, BeiDou, and GLONASS with a low time to alert for any detected anomalies. The health and status information includes use/do not use flags for each satellite in a given constellation, quality indicators for each signal broadcast from each satellite, and real-time precision multi-constellation, multi-frequency broadcast navigation message error estimation. This Monitoring System leverages a ground network of flexible GNSS receiver hardware that can be firmware or software upgraded to support future signals such as Xona PULSAR in Low Earth Orbit (LEO). GNSS and other measurements are transferred to a centralized processing facility to derive insights about signal and service quality and to detect anomalous behavior. These insights are assembled into alert messages which are disseminated to end users via communication channels such as PULSAR in the long term. This enables fast and efficient time to alert for end users who have business-, mission-, or safety-critical reliance on PNT. We aim to demonstrate the extensibility of this system to include future GNSS constellations such as PULSAR and indicate how it can be extended to include other Alt PNT signals. This demonstration will focus on showcasing the inclusion of the PULSAR system, specifically the inclusion of estimating PULSAR ranging errors for use cases such as anomaly detection.