Unscented Kalman filter with open-loop compensation for high dynamic GNSS carrier tracking

Abstract

Because of the limit of the loop-band, traditional carrier tracking loop of GNSS receiver can't work in high dynamic conditions with large Doppler frequency, for which an open-loop carrier tracking method based on UKF is proposed. Upon this new tracking loop, the four-dimensionality UKF phase estimator and a compensator is designed to modify the estimative values. By simulating the high dynamic trace of the plat of GNSS receiver, this new method is compared to the closed loop mainly in the aspects of tracking errors, compensation effects and unlocking probability. Simulations show that (1) the proposed open-loop compensation method can give attention to the precision and the dynamics better, with high stability, (2) compared with the closed loop, the open-loop carrier tracking method can improve the tracking precision, with 50% decrease of the tracking errors; and (3) the convergence of this new method is much better, leading to lower unlocking probability.