Multimodal data fusion for SB-JPALS status prediction under antenna motion fault mode

High positioning accuracy and system integrity are crucial for the Sea-based Joint Precision Approach and Landing System (SB-JPALS) to ensure life safety in carrier landing. The antenna motion of shipboard receivers may introduce large positioning error, which is one of the primary failure modes affecting the SB-JPALS integrity. Multimodal data fusion based on dual-frequency GPS observables and antenna motion information is applied to monitor the failure and enables the system to alarm message once position domain error caused by antenna movement exceeds a threshold. Monitoring algorithm uses multiple reference station architecture, selects integrated translating error of all valid reference antennas as the monitor measurement, and establishes a monitor decision-making model based on fault vertical protection level to evaluate the integrity performance. Multiple antenna motion errors are fused to be the integrated translating error and relevant methodology is described. Firstly the associated equation is built between individual antenna motion error and inter-antenna baseline motion error. The latter is regarded as known variables due to feasibility to capture them on the mobile ship platform. Then each antenna motion error is calculated and projected onto satellite line-of-sight direction. Finally the integrated error is obtained by averaging all antenna motion errors. The experiment data analysis result shows that individual antenna motion error derived from inter-antenna baseline errors is consistent with its real value, and the vertical protection level of the integrated translating error computed by multimodal data fusion processing based on multiple reference antennas is smaller than that by individual antenna information, namely, the system achieves better integrity.