Compensation of selected availability using a GPS/INS extended Kalman filter

The authors describe research to compensate for selected availability (SA) corruption by modifying the Kalman filter used in a typical Global Positioning System/inertial navigation system (GPS/INS) integration. Two modified filters are developed: one filter that models SA using individual error-states and another filter that compensates for SA by increasing the measurement noise. Neither of these filters totally eliminates the corruption due to SA, but both provide a significant increase in the accuracy of the navigation solution.<<ETX>>