Passive gravity gradiometer navigation system

A totally passive navigation system using gravity gradient map matching techniques is described. The system requires no external information and is nonemanating and nonjammable. The system consists of an inertial system updated by position fixing from map matching to gravity gradiometer outputs. The advantages of the system over existing terrain map matching systems are covered. The difficult instrumentation problem is solved with proven hardware by the Bell rotating accelerometer gravity gradiometer system. The issue of the database necessary for gravity gradient map generation is addressed. The results of an accuracy analysis in the form of a parametric study for such variables as altitude, speed, number of gradiometers, quality of the gradiometers, and quality of the inertial components are presented