利用单频码、相位和GRAPHIC组合3个观测量的两两组合可以构造3种单频精密单点定位观测模型:基于码和GRAPHIC观测量的C-G模型,基于GRAPHIC和相位观测量的G-P模型和基于码和相位观测量的C-P模型。针对电离层延迟改正问题,考虑了最高精度的模型改正方法——IGS格网电离层改正和估计电离层延迟参数两种方案。采用全球分布的15个IGS监测站16d的数据和一组机载动态GPS数据进行解算实验。结果表明,不同观测模型和不同的电离层延迟处理方法,定位效果有明显差异。
Based on code, carrier phase and their combination so called GRAPHIC observa- tion, three types of observation model for Single-Frequency Precise Point Positioning(SF- PPP) were presented, named as :"C-G model" making use of Code and GRAPHIC observa- tion, "G-P model" making use of GRAPHIC and Phase observation and "C-P model" making use of Code and Phase observation. We considered two approaches to eliminate ionospheric effect : first ,to remove the ionospheric delay tional GNSS Service (IGS) which is the most with ionospheric map data from the Interna- accurate ionospheric model~ second, to esti- mate the ionospheric path delay parameter together with receiver position, clock offset and so on. SFPPP experiments were carried out with static GPS data collected at 15 stations of IGS through day 75 to 90 in 2011 and airborne GPS data collected on September 5th 2008. It's shown that different models and ionospheric elimination approaches lead to different positio- ning accuracy. Among all the three models and two approaches, G-P model and C-P model with estimation of ionospheric path delay, produce the best result for both static and kine- matic positioning. Just saying the first ionospheric elimination approach, C-G model enjoy the best result. Our work indicates that, by adopt suitable observation and ionospheric elimi- nation approach, an accuracy of a few centimeters for static positioning and several delimiters for kinematic positioning is achievable with SFPPP.