基于空间变异特性的格网电离层延迟估计方法

Estimation Method of Ionospheric Delay of IGP Based on Spatial Variability

广域增强系统采用格网模型校正用户电离层延迟误差,为保证理想的校正效果,必须精确估计格网点电离层延迟。电离层延迟的空间相关性是完成这一估计的理论依据。针对传统反距离加权法因不能准确描述这种空间相关性而使得估计效果受限的问题,依据空间统计学原理建立了电离层延迟空间变异函数模型,提出一种新的权值计算方法,并通过实际观测数据进行了仿真验证。结果表明,相比于传统方法,这一方法能明显改善格网点电离层延迟估计效果,尤其在穿透点观测数据稀疏的区域,其改善效果更为明显。

The Wide Area Augmentation System( WAAS) corrects the ionospheric range delay for its users using the Grid algorithm,so it is crucial for its user how accurate is the estimation of the ionospheric grid points( IGPs). The spatial correlation is the foundation of the estimation,which couldn't be accurately characterized by the inverse distance weighted method. The work focuses on the conception of the variogram,and proposes a new weighted algorithm. The data analysis proves that the more accurate estima-tion of delay of IGPs can be acquired,especially at the areas where the measurements are sparse.