Reasearch On Increasing GPS Elevation Accuracy

With more and more application of GPS technology in deformation monitor, higher GPS elevation accuracy is in demands. Sometimes, we hope it to reach the same accuracy of planar position. However, for many factors restrict the increase of the accuracy of elevation direction, its error is usually 1-3 times of planar error with the most software of GPS baseline resolution nowadays, which can not satisfy some surveying. At the same time, troposphere delay is one of he main influence factors.In this paper, the main GPS survey errors are discussed firstly, and troposphere delay and some methods correcting it in the GPS data processing such as Modal Correction, Double Difference Weaken, Parameter Estimate are introduced in detail. Then, considering the aspects of satellite cutoff elevation, survey station meteorology, troposphere delay model and parameter estimate, the influences of troposphere delay in elevation survey are discussed. The GPS monitor data of geodetic distortion in both the main flood regions of middle and lower reaches of the Yangtze River and Ningbo in East China's Zhejiang Province are calculated and analyzed as the cases. Final, thinking of the influence of the variety of the antenna phase center. Some useful conclusions are drew and some valuable suggestions are presented, making a exploration to increase the GPS elevation accuracy.