Patent ID: 7916070

Claim:
A method of eliminating the use of an inertial measurement unit (IMU) for a global positioning system (GPS) receiver while still retaining anti-jamming benefits of tightly coupling with navigation estimates, the method comprising: determining a position associated with the GPS receiver via GPS signals received by the GPS receiver such that the position is known, the GPS receiver having code and carrier tracking loops; directly advancing, using course, speed, acceleration, and time obtained from GPS, the known position obtained via GPS to generate a propagated position associated with the GPS receiver for a next navigation filter cycle of the GPS receiver without the use of the IMU; generating range and range rate estimates to satellites, wherein each range and range rate estimate for a particular satellite is generated by projecting (a) vehicle position, velocity, and attitude estimates and (b) satellite position, velocity, and acceleration (PVA) data, wherein the satellite PVA data is based on ephemeris data that had been retrieved from a navigation message from the particular satellite; driving the code and carrier tracking loops of the GPS receiver based on the generated range and range rate estimates, which are based on the propagated position of the GPS receiver and on positions of satellites that are being tracked, such that the tracking loops are tightly coupled with the propagated position; wherein determining, advancing, and driving are performed by the GPS receiver during tracking of previously acquired GPS signals such that the GPS signals remain tracked.