DEVELOPMENT OF A DIFFERENTIAL GPS NAVIGATION FILTER WITH AUTONOMOUS FAILURE DETECTION

THIS PROPOSAL DESCRIBES AN INNOVATIVE FILTERING TECHNIQUE THAT CAN BE USED TO DETECT AND REJECT OUT-OF-TOLERANCE MEASUREMENTS FROM A DIFFERENTIAL GPS NAVIGATION SOLUTION. THE TECHNIQUE CAN BE APPLIED FOR BOTH MOBILE AND STATIC APPLICATIONS AND COULD BE INTEGRATED INTO SHIPBOARD OR REFERENCE STATION GPS RECEIVERS. USING THE FILTER DESIGN PROPOSED, ERRORS CAUSED BY MULTIPATH, SATELLITE, RECEIVER ORREFERENCE STATION FAILURES CAN BE AUTOMATICALLY DETECTED ANDIDENTIFIED USING REDUNDANT MEASUREMENTS FROM AN "ALL-IN-VIEW" RECEIVER. THE REMAINING VALIDATED MEASUREMENTS ARE THEN APPLIED IN A NAVIGATION FILTER TO COMPUTE A PRECISE DIFFERENTIAL GPS SOLUTION. THE ALGORITHM OPERATES AUTONOMOUSLY AND PROVIDES FIGURES OF MERIT ON BOTH THE ACCURACY AND INTEGRITY OF THE DIFFERENTIAL SOLUTION. UNDER THE PHASE I PROJECT, THE FILTER DESIGN WILL BE DEVELOPED AND TESTED USING THE NAVTEST SIMULATION TOOL DEVELOPED BY NAVSYS. A FINAL REPORT WILL BE PREPARED DESCRIBING THE FILTER DESIGN AND THE SIMULATION RESULTS DEMONSTRATING THE PERFORMANCE AND FAILURE ISOLATION POSSIBLEUNDER DIFFERENT SATELLITE CONSTELLATION SCENARIOS AND WITH DIFFERENT RECEIVER DESIGNS. THE PHASE I RESULTS WILL BE USED TO PREPARE A SYSTEM SPECIFICATION FOR A HARDWARE DEMONSTRATION TO BE PERFORMED UNDER PHASE II PROJECT. A FULL DIFFERENTIAL GPS SYSTEM WILL BE IMPLEMENTED UNDER PHASE II AND TESTED TO DEMONSTRATETHE CAPABILITY OF REJECTING MULTIPATH AND RECEIVER FAILURES.THE INTEGRITY MONITORING ALGORITHMS THAT WILL BE DEMONSTRATED UNDER THIS CONTRACT PROVIDE THE CAPABILITY TO AUTONOMOUSLY DETECT AND ISOLATE FAILURES THAT DEGRADE THE DIFFERENTIAL GPS PERFORMANCE. THESE ALGORITHMS CAN BE USED IN MARINE, AIR AND LAND DIFFERENTIAL APPLICATIONS WHERESAFETY IS CRITICAL.