Patent attributes
A system and method for detecting and excluding false GPS signals are disclosed, which predict a GPS measurement value with a high degree of confidence, compare the predicted value with measured values, and reject a false measurement based on the comparison results. As one example, a tightly coupled GPS/Inertial Navigation System (GPS/INS) is disclosed, which uses a Kalman filter for comparison of a predicted GPS measurement value with measured values (e.g., the residuals) to form the basis for the rejection of false measurements. This rejection is referred to as a chi-squared reject, and can be extended in time in order to apply the same test to a reacquired signal following the loss of an original validated GPS signal. The Kalman filter propagates the receiver's clock bias rate, and enables the system to predict the GPS measurements at the time of reacquisition. The residuals are compared to a limit defined by the uncertainties of the prediction and the measurement errors expected to be involved.
