Study And Practice On Beidou Satellites Precise Orbit Determination Based On Reduced-Dynamic Method

While the establishment of the GPS system leads satel ite navigation into a new era of al-around, global and al-weather, China develops the Beidou satel ite navigation system independently. Compared to GPS, BDS lags behind in every aspect for later started and longer period. Based on the Beidou data analysis center of China University of Mining and Technology, this paper studies the theory of the motion of the Beidou satel ites, and improves the accuracy of the estimation of the position of the satel ite, which has a strong practical significance.Under the guidance of the theory of the reduced dynamic force, the dynamic model and the observation model are established, and the orbit determination of the Beidou satel ite is carried out by using the data of the tracking station in the actual calculation process. The main content and work of this paper are as follows:1. The dynamic model and observation model are established based on the Reduced Dynamic Method of "2 steps", focusing on the realization of satel ite dynamics equation. Based on the two body problem, the perturbation contains non spherical gravitation, the three body problem and solar radiation pressure are studied. The numerical calculation of 3 kinds satel ites that GEO/IGSO/MEO is carried out, and the influence degree of the perturbation force to all kinds of satel ites is discussed.2. According to the characteristics of satel ite motion, the experiment was carried out using Adams-Moulton and Shampine-Gordon methods in the course of satel ite orbit integration, and a scheme is proposed to select the method with the eccentricity ratio as the threshold value. And, the truncated singular value and the regularization method are used to solve the problem that the ill posed problem of GEO satel ite, which can get better effect of the regularization method, and the parameter selection is more reasonable.3. Grey system, least square collocation, Kalman filter theory are selected respectively for small amount of data of short-term forecasting, large amounts of data short-term forecast, large amounts of data long-term prediction experiment and get the applicable data. With a large number of data of the long-term forecast of orbit clock difference forecast experiment, the accuracy of the forecast in the experiment is 0.5~1.5 ns.4. Precise orbit determination. Based on LAMBDA search algorithm, LC combination, the least squares and Calman filtering method are used to calculate the fuzzy degree, and the best method is selected to solve the fuzzy degree. Then broadcast ephemeris are used to solve the reference orbital moment parameters, and the track initialization is calculated by perturbation correction fitting, after that, combined with tracking station coordinates, observation data, fuzzy degree results to solve satel ite orbit, at last,the experimental set orbit precision reach 0.2~2 m.