区域电离层估计方法在网络RTK中的应用

Application of regional ionospheric parameter estimation in network RTK

针对常规网络基线解算采用的三步法模型中,伪距观测值精度较差导致基线模糊度出错概率较大的问题,提出采用载波相位观测值,基于电离层延迟在区域范围内的站间相关性和星间独立的误差分布特性,建立区域电离层参数估计的方法:利用低阶多项式及映射函数来表征区域的电离层延迟物理分布特性;采用基于载波相位观测值的参数滤波方法消除伪距观测值误差影响,提高模糊度参数和电离层参数估计精度。实验结果表明:该模型反演区域电离层误差精度可比常规方法提高47%;该方法用于地基增强定位系统后,中长基线三星系统模糊度固定卫星数大于16颗的时段超过95%;可有效改善网络RTK定位精度,其中动态跑车实验除了过隧道的时段,其他时段全部达到固定解。

Aiming at the problems that it is often wrong for ambiguity resolution due to the pseudo-range observations with poor accuracy in the conventional network baseline solution,the paper proposed a regional ionospheric parameter estimation method by using carrier phase observations based on the regional inter-station correlation and error distribution of inter-satellite independence for ionospheric delay:low-order polynomials and mapping functions were used to characterize the physical distribution of the regional ionospheric delay,the parameter filtering method based on the carrier phase observation was used to eliminate the influence of the pseudorange observation error and increase the estimation accuracy of the fuzzy parameter and the ionospheric parameter.Experimental result showed that the retrieval accuracy of regional ionospheric error by the model would be 47%higher than that by the conventional method;the times inwhich the satellite number was greater than 16 with fixed multi-system ambiguity of middle-long baselines would be more than 95%;the positioning accuracy of network RTK could be effectively improved,meanwhile the experiment of dynamic sports car could obtain fixed solutions all the time except in tunnel.