Impact Analysis of Long-distance Real-time Dynamic Differential  ]Positioning Based on Ephemeris Type

   The roving station often can’t obtain the fixed solution when it is more than 30 km between the distance of them with distance away from the reference station. To achieve the real-time processing of the real-time dynamic difference over a long distance, the choice of the GAMIT software almost real-time kinematic TRACK processing module, real-time deformation sequence. TRACK module of GAMIT software is almost chosen to process real-time dynamic difference data over a long distance to achieve real-time deformation sequence. Surveying and mapping workers almost all choose IGS to calculate the of coordinates of roving station and improve the precision of coordinates,but time delay of IGS ephemeris is very long (generally 12 hours), the efficiency of time is low. To solve the problem, the authors do experiments that using the rapid ephemeris (IGR) and precise ephemeris afterwards (IGS) are respectively process the data of roving station. The results of experiments are highly. corresponding. Research results show that has very little to do with choosing the type of precise ephemeris which is used the TRACK module of GAMIT software is used to process data accuracy of station-coordinates, zenith delay and clock error etc. The conclusion has important reference value to surveying and mapping workers in the aspect of improving the time-efficiency.