A carrier phase only processing technique for differential satellite-based positioning systems
This dissertation presents the concept and an algorithm for processing carrier phase measurements from satellite-based signal sources, to determine the three-dimensional (3-D) relative position between two receivers. The proposed algorithm is based on an extended Kalman filter, which uses satellite geometry variations, together with an accurate relative position propagation, to converge the user's 3-D relative position down to sub-meter level within a few minutes. This converged position can serve as the initial estimate to launch a small ambiguity search, and then refine the user position to centimeter level accuracy after the ambiguities are resolved. As part of the framework of this dissertation, a low-earth-orbit (LEO) satellite is integrated into the modified extended Kalman filter (MEKF) to accelerate the convergence, and a modification scheme for the measurement model is provided to correct the systematic errors of the MEKF, due to the LEO satellite's lower orbit. Also, three statistical calibration methods are developed and evaluated to accommodate new measurements into the MEKF. The convergence property of the MEKF is found to be effectively characterized by the smallest singular values of the observability grammian. Finally, a combined GPS/GLONASS processing algorithm is presented, which uses the GLONASS and GPS measurements to speed-up the convergence of the MEKF estimation process. After resolving the ambiguities for the GPS measurements, the ambiguity-resolved position solution is used to calibrate the GLONASS interchannel biases. The MEKF was successfully verified by post-processing the flight test data from a Boeing 757 aircraft on the final approach to an airport. Position accuracies were found to be at the sub-meter level. Centimeter level position accuracy was achieved after a small ambiguity search was implemented to resolve the carrier phase cycle ambiguities.
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:extended kalman filter three dimensional 3 d relative position low earth orbit glonass mekf
Date of Publication:01/01/1999