从GPS实时精密单点定位所需的高精度实时卫星轨道和钟差产品出发,对IGU的精度及其与时间的相关性进行了分析.研究了基于区域CORS网络的卫星钟差实时估计方法,并与IGS最终钟差产品进行了精度比较.然后基于实时的IGU轨道和估计出的实时钟差进行了实时PPP解算实验.分析结果表明,IGU实时预报轨道随着外推时间的增长精度逐渐降低,满足近似的线性关系,多数卫星外推9h的轨道误差约为6cm,同时发现部分年代较久的卫星预报轨道误差明显较大.实时反演的钟差的平均RMS可以达到0.081ns.对钟差反演区域(重庆CORS)的模拟实时PPP定位平均收敛时间为14.57min,1h定位N/E/U方向中误差分别达到0.55/2.93/2.01cm;对江苏CORS站点的模拟实时PPP定位平均收敛时间为14.56min,1h定位N/E/U方向中误差分别达到了1.20/4.05/8.42cm.
Starting from the requirement of high-precision real-time satellite orbit and clock products for the GPS (global positioning system) real-time precise point positioning (PPP), the accuracy of IGU (international GNSS service ultra-rapid) and its correlation with prediction time are analyzed.