A three-step Kalman filter algorithm for near real-time estimating tropospheric wet delay on GPS reference stations

Using priori information from known coordinates for reference stations, based on tacombination of ultrarapid ephemeris, a three-step kalman filter algorithm for near real-time estimation of tropospheric wet delay on reference stations is proposed. In this algorithm, wide lane ambiguity and pseudorange multipath error are separated by using a Kalman filter, and then, using the Kalman filter for separating L1 ambiguity and tropospheric wet delay based on na ionosphere-free combination model. After that estimating an accurate relative tropospheric wet delay parameter using the correctly fixed L1 ambiguity back substitution method and rebuilding the Kalman filter. The feasibility and accuracy of the algorithm is verified through numerical examples.