一种基于系数择优的低阶球谐电离层延迟改正模型

Optimized Spherical Harmonic Function Model for Ionospheric Delay Correction

针对单频接收机的电离层延迟改正问题,提出了一种基于系数择优的低阶球谐电离层延迟改正模型.按照电离层延迟改正模型参数择优问题的描述,明确参数优化的目标和约束条件,根据参数选择可编码的特点,提出了利用遗传算法进行参数择优的方法及步骤.以欧洲定轨中心(CODE)提供的电离层数据作为参考标准,对参数择优模型、低阶球谐模型和Klobuchar模型模拟的区域电离层VTEC精度进行了比较分析.结果表明,较之相同系数个数的低阶球谐模型,参数择优模型精度平均改进了1~2TECU,而且比Klobuchar模型及低阶球谐模型能更好地反映电离层的周日变化及纬度变化特征.

Aiming at the ionospheric delay correction of single-frequency receiver,this paper proposes an optimized low-order spherical harmonic function model.Firstly,the description method of optimized ionospheric delay correction model is discussed and the objective and restraint condition of optimizing coefficients are defined.Then,according the characteristics that coefficients can be encoded,method and steps of using genetic algorithms to optimize coefficients are presented.Lastly,the accuracy analysis and comparison are made with Klobuchar based on the the ionosphere VTEC produced by CODE.The results show that accuracy of the optimized model is improved.It has an improvement about 1~2TECU than the low-order spherical harmonic function model with the same number of coefficients and can better reflect the daily change of VTEC and the characteristics which vary with latitude.