Satellite Positioning and Orbit Determination System SPODS:Theory and Test

The Satellite Positioning and Orbit Determination System(SPODS)is a software package for GNSS positioning/orbit determination,developed by the Xi'an Research Institute of Surveying and Mapping.So far it has been able to treat GPS data and has the capability of high precision GPS positioning and orbit determination.The underlying theory and the performance test are briefly addressed.The test utilizes the GPS data collected from some 127IGS stations during days 4~10of 2009.The results show that the rms 1Ddifference is 1.1cm between SPODS orbits and final IGS combined orbits,and that the repeatability of daily solutions of station coordinates is 1.5mm for horizontal components,and 4.5mm for height component,and that the consistency of ERP solutions with final IGS values is 0.025mas,0.093mas and 0.013ms/d respectively for pole coordinates and changes in length of day.