Development of a Real-Time Monitor for Satellite Anomalous Clock and Orbit Errors

The thesis focuses on the development of a real-time software monitor to detect anomalous Global Positioning System (GPS) satellite clock and orbit errors for any one of the satellites in view. The monitor not only detects the anomaly, but also identifies the satellite and quantifies the magnitude of the anomaly to alert the users of the system.

Different methods based on the pseudorange residual are used to detect the anomaly and to identify the satellite. Both differenced pseudorange residual and subset formation method are used. In addition, accumulated Doppler range residuals were used to characterize the error growth over time. All methods used were verified using precise orbits and clock products. Detection threshold values are calculated based on error statistics for pseudorange and ADR measurements.