北斗不同电离层模型精度分析

目前北斗系统播发多种电离层模型参数，用户使用时容易产生以下问题：①同一历元不同卫星播发同一电离层模型，其值不完全相同；②北斗二号、北斗三号分别播发的Klobuchar电离层模型参数值存在差异；③对于能同时接收到3种电离层模型（BDS-2 Klobuchar、BDS-3 Klobuchar及北斗全球电离层延迟修正模型（BDGIM））的基本导航用户如何选取合适的电离层模型。针对以上问题，本文首先提出采用最大投票法策略，对同一历元相同电离层模型但值不同的参数进行合理合并，然后以IGS分析中心的电离层产品为基准，对以上3种北斗电离层模型进行了精度分析和对比，最后基于等效距离误差进行了验证分析。试验结果表明，BDS-2 Klobuchar、BDS-3 Klobuchar虽然模型值差异较大但模型精度十分接近，而BDGIM模型精度最高，相对于前两者在中低纬地区平均提升10%，在两极地区的提升更加明显，平均提升61%。

Evaluation on the precision of different BDS ionosphere model

At present, BDS broadcasts a variety of ionospheric model parameters, which causes the following confusion when users use it:①Different satellites may broadcast the same ionospheric model with different values in the same interval. ②The klobuchar model broadcast respectively by BDS-2 and BDS-3 are quite different. ③How to select the proper model from the three types of ionospheric model (BDS-2 Klobuchar、BDS-3 Klobuchar、BDGIM) that can be received at the same time. To propose a solution overcoming current shortcoming, this paper firstly proposes the maximum voting strategy to reasonably combine the parameters of the ionosphere models in the same calendar but with different values. Then, based on the ionosphere products of IGS analysis center, the accuracy of three BeiDou ionosphere model is analyzed and compared. Finally, the validation analysis is carried out based on the user equivalent range error(UERE). The results show that although the model values of BDS-2 Klobuchar and BDS-3 Klobuchar are quite different, the accuracy of the model is very close. Besides, the accuracy of BGDIM model is the highest, with 10% improvement compared with BDS-k8 model in the middle and low latitude area, and 61% improvement in the polar regions.