Periodical orbit maneuver makes a serious problem for navigation users to get correct Geostationary
(GEO) orbit information in real-time. As a result, it is very difficult to use GEO satellite for navigation
application purpose. In this presentation, the precision of the orbit determination of GEO satellite
without maneuver operation has been introduced at first. Then, two strategies of orbit determination
during satellite maneuvers are discussed in details. One method is called as maneuver force modeling;
the other is empiric force parameter estimation. The results show the residual is of the order of 40 cm
by using these strategies, and the position difference between dynamic orbit and kinematics orbit is
about 10 m.
The new generation of space datum in China should comply with the latest IERS (International Earth Rotation and
Reference System Service) convention as much as possible. This paper has deeply addressed and researched the main
improvements of the current version IERS Conventions (2003), including the changes of the Terrestrial Reference
System, the Celestial Reference System, and the transformation between them, the tide correction and so on, which
would undoubtedly benefit the realization and maintenance of our space datum. Based on PANDA (Position And
Navigation Data Analyst) software developed by GNSS Center of Wuhan University, we analyzed the effect of
improvements of the IERS Conventions (2003) on precise orbit determination and precise positioning. The results show
that the effect of improvements of models of the coordinate transformation between the celestial and the terrestrial
reference system and tide correction (including solid earth tide, ocean tide and polar tide) on precise orbit determination
are 4mm, 9mm and 5mm in terms of RMS in along, cross and radial direction of the track; and the effect of the
improvement of the tide models on positioning is basically under 0.6mm, and the RMS of the differences are 0.3mm,
0.3mm and 0.2mm in X, Y and Z.
One goal of the IERS to define and maintain the ITRF is to combine all major space geodetic techniques (GPS, VLBI, SLR, LLR and DORIS solution in the SINEX format) into an integrated consistent set of high-accuracy products. In such a combination, estimating and removing the systematic errors between different SINEX files is an important issue. For this purpose software GNAS (Geodesy Network Analysis System) is developed, which is able to estimate 7 Helmert transformation parameters of station coordinates within the process of combination. Besides, the GNAS software enables us to combine EOPs and station coordinates not only separately, but also simultaneously. We discuss the advantages and disadvantages when systematic parameters are estimated for each Analysis Center (AC) or for each SINEX file. One can estimate either the whole 7 Helmert parameters or only a set of them (e.g. without 3 rotation parameters). Different procedures have different effects on the combined solutions, especially when EOPs and station coordinates are combined simultaneously. Detailed discussions, numerical examples and some results analysis are given in this paper.
Proc. SPIE. 6752, Geoinformatics 2007: Remotely Sensed Data and Information
KEYWORDS: Solar radiation models, Data modeling, Satellites, Satellite navigation systems, Data processing, Navigation systems, Software development, Atmospheric modeling, Global Positioning System, Data analysis
Firstly, the PANDA (Position And Navigation Data Analysis) software, developed by Wuhan University, is introduced in this paper. And then we present a new method for the precise orbit determination (POD) and near real-time orbit prediction using the regional tracking network by the PANDA software. The orbit determination results are compared with final precise orbit provided by IGS and the accuracies are given detailedly. The results should encourage the realization of regional high precision orbit determination services.