eLoran系统ASF网格应用算法研究

Analysis of ASF Grid Application Algorithm in eLoran System

ASF网格是提高增强型罗兰(Enhanced Long Range Navigation,eLoran)系统精度的重要方法。根据所在网格四个顶点的附加二次时延(Added Secondary Factor,ASF)值通过网格应用算法得到待测试点的ASF值,一定程度上比公式计算的ASF值更准确。在计算过程中,用户四个顶点ASF值的测量误差会传递给用户,同时内插算法本身也会引入误差,此时内插算法的选择尤为重要。本文通过仿真、分析比较几种常用的内插算法,得出结论:反距离插值算法引入的误差最大,双线应插值算法引入的误差最小,而且误差呈现一定层次感,网格从内到外误差逐渐减小。

ASF grid is an important method to improve the accuracy of eloran time service. According to the ASF values of the four vertices of the grid,the ASF values of the tested points are obtained by the grid application algorithm,which is more accurate than the ASF value calculated by the formula to a certain extent. In the calculation process,the measurement error of ASF values of four vertices will be transmitted to the user,and the interpolation algorithm itself will also introduce errors,so the selection of interpolation algorithm is particularly important. Through simulation,several interpolation algorithms are analyed and compared,it is concluded that the error introduced by the inverse distance interpolation algorithm is the largest,the error introduced by the double line interpolation algorithm is the smallest,and the error presents a certain sense of hierarchy,and the grid error gradually decreases from the inside to the outside.