MGEX北斗差分码偏差两种精确处理方法对比分析

差分码偏差是北斗卫星导航系统（BDS）在高精度定位和电离层建模中需精确处理的系统误差之一.利用MGEX发布的2017年全年和2018年6月的BDS卫星的差分码偏差数据，比较分析了DLR和CAS分别解算的BDS卫星差分码偏差的日解值、月平均值和稳定性的变化特性.分析结果表明，DLR与CAS估算的BDS卫星差分码偏差值差异不大，具有较好的一致性；2017年CAS估算的BDS卫星C2I-C6I差分码偏差稳定性略优于DLR，C2I-C7I差分码偏差稳定性与DLR相当，且均具有较高稳定性；2018年6月DLR C2I-C6I差分码偏差月平均值稳定性优于CAS；C2I-C7I差分码偏差的稳定性明显优于C2I-C6I差分码偏差，卫星差分码偏差月平均值稳定性优于日解值稳定性. 

Comparative Analysis of Two Precise Processing Methods for MGEX BDS Differential Code Biases

Differential Code Bias (DCB) is one of the systematic errors that must be dealt with in BDS-based high-precision positioning and ionospheric modeling. Firstly, two different processing strategies proposed by DLR and CAS for estimating BDS differential code biases are introduced respectively. Secondly, using the BDS differential code bias products released by MGEX in 2017 and June 2018, the variation characteristics of daily solutions, monthly mean values and the stability of BDS satellite DCB estimated by DLR and CAS, respectively, are compared and analyzed in this paper. The results show that both the DLR DCB and CAS DCB exhibited high stability in 2017, and the stability of C2I-C7I DCB was better than that of C2I-C6I DCB. Besides, the stability of monthly mean values of BDS satellite DCB was better than that of daily solutions. In June 2018, the stability of DLR DCB is slightly better than that of CAS DCB, and the difference between DLR DCB and CAS DCB ranged from -0.58ns to 1.07ns, indicating that the BDS satellite DCB estimated by CAS and DLR had a good consistency. BDS satellite DCB products provided by DLR and CAS have high reliability in correcting differential code biases for global BDS users.