SLR Data Processing And Analysis Based On LP Estimation

The orbit accuracy of the satellite orbit is required to be higher with the development of space surveying. The least square estimation (LS estimation) theory is built on the basis that the error is normally distributed and the function model is linear. The gross error will badly affect the reliability of orbit determination which is estimated by LS estimation because it is poorly resistant to the effect of gross error. But the gross errors in the observations are inevitable. So it is not reliable to estimate parameters of orbit by only LS estimation. LP estimation ( Least P-norm Estimation ) with the robust character is the most probable estimation when measuring errors obey P-norm distribution, it can reduce sufficiently or eliminate the effect of gross errors to obtain robust estimates efficiently in the presence of gross errors. Based on the best estimation theory of dynamic determining satellite orbit, this dissertation puts the robust LP estimation in the precise orbit determination. The main contents are as follows: 1. Study on the theory of LP estimation.The principle, properties and efficiency of LP estimation areintroduced in detail. Besides, the estimation method and the accuracy evaluation criterion of LP estimation are also discussed. Basing on the influence function of M estimation, we deduce the function of LP estimation, and discuss the relation between P value and the robustness of LP estimation. The conclusions are drawn on the basis of analysis: the robustness will decline with P value.2. Simulation test of LP estimation.We simulate three kinds of observations: normal, normal with gross errors and P-normal distribution, and process these data by using LP estimation and LS estimation respectively. Comparing the results between LP estimation and LS estimation, we find that LS is the best estimation when errors obey normal distribution, LP estimation obviously better than LS estimation when errors obey P-normal distribution or there aregross errors in the data.3. Applying of LP estimation on the precise orbit determinationThe principle of the precise orbit determination is briefly introduced. Besides, the realizing of LP estimation on the precise orbit determination is discussed in detail. We improve the precise orbit determination software SHORDE owned by Shanghai Astronomical Observatory, CAS and introduce LP estimation to the software. Using SHORDE, we determine the precise orbit of Lageos and CHAMP satellites. The comparisons among the parameters estimated show that, as compared with LS estimation, LP estimation makes much progress on not only the accuracy of orbit but also the using efficiency of data when the quality of observations is bad or errors do not obey normal distribution.