Spatial gradient monitor for GBAS

In this paper, we develop a ground monitor capable of detecting anomalous signal-in-space(SIS) spatial gradients for rising, newly acquired, and re-acquired satellites in the Ground Based Augmentation System (GBAS). These gradients can be caused by satellite orbit ephemeris faults and ionospheric fronts. The monitor utilizes differential code and carrier phase measurement across multiple reference receiver antennas as the basis for detection. We show that the new monitor significantly improves the detection performance over existing fault detection algorithms under tropospheric turbulence and that it is capable of meeting Category III precision approach and landing requirements.