Chapter 24 Fitting Method and Accuracy Analysis of Broadcast Ephemeris in Hybrid Constellation

摘要

Broadcast ephemeris parameter is an important reflection of navigation system service performance. In hybrid constellation, GEO, IGSO and MEO satellites have different dynamic characteristics which lead to different fitting performances. In this article, the basic physical meaning of ephemeris parameters are analyzed, and the evaluation for the variation characteristics of fitting parameters is carried on. Several improved algorithms are proposed from the aspect of mathematical processing, which effectively eliminates the unsuitability in the parameter fitting of GEO. The fitting accuracy of 3 types of satellites are analyzed based on the 16-parameter model, and then the evaluation of fitting performance is completed. It is proved in the experiments: the high accuracy can be realized for the 3 types of satellites, and even the accuracy is prior to 1 cm for most time. For GEO, the accuracy can be sub-centimeter, while the accuracy can be millimeter for IGSO and MEO satellites. In summary, the 16-parameter model is enough to meet the centimeter level application requirement.