中文摘要：

依据精密单点定位（PPP）原理编写天顶对流层延迟估计程序,分别利用所编程序和GAMIT软件进行实测数据解算,将所得数据与IGS网站提供数据进行对比分析,结果显示PPP与双差法估计对流层延迟都有较高精度;但在双差法解算过程中发现,无远距离测站参与解算会影响对流层延迟估计的精度。

英文摘要：

On the basic of theory of PPP（Precise Point Positioning）,we developed a program to calculate the ZTD,then we used the program and GAMIT to process the real observations.Compared the results with the data provided by the IGS,it is found that two methods both have high accuracy.Howver,the process results without far-away station data are of very low accuracy,it shows the advantage of Precise Point Positioning in the calculation of ZTD.