ELECTROMAGNETIC TRANSMISSION THROUGH PLASMA, ADDING GPS TO INERTIAL PLATFORM

COMBINING GPS AND INERTIAL NAVIGATION SYSTEMS ON FUTURE ADVANCED HYPERSONIC AERODYNAMIC WEAPON SYSTEMS COULD PROVIDE SUPERIOR NAVIGATION PERFORMANCE COMPARED WITH CURRENT INERTIAL PLATFORMS ALONG AND AT A LOWER COST. GPS SOLUTIONS ALONG WOULD BE DIFFICULT BECAUSE OF PLASMA SHEATHING PERIODS STARTING ABOVE 150 KFT AND LASTING UNTIL THE VEHICLE VELOCITY FALLS BELOW 15 KFT/SECOND OR LOWER. THE INERTIAL MEASUREMENT UNIT (IMU) WOULD PROVIDE NAVIGATION SOLUTIONS DURING THIS GPS COAST PHASE. THE ADDITION OF GPS COULD RESULT IN REDUCED PERFORMANCE REQUIREMENTS ON THE IMU. PLASMA SHEATHING ISSUES ON GPS PERFORMANCE ARE ADDRESSED INCLUDING REDUCTION OF SIGNAL STRENGTH, INCREASED SYSTEM NOISE TEMPERATURE CAUSED BY PLASMA AND ANTENNA WINDOWS, AND ANTENNA COVERAGE CHANGES. PLASMA DIAGNOSTICS AND PLASMA ALLEVIATON ARE EXAMINED FOR FUTURE FLIGHT TESTING OF THE CONCEPT.