卫星差分码偏差对北斗三号双频精密单点定位的影响

Influence of satellite differential code bias on BDS-3 dual-frequency precise point positioning

为探讨北斗三号系统不同频点组合卫星差分码偏差(differential code bias,DCB)对精密单点定位(precise point positioning,PPP)的影响,推导北斗三号系统不同频点无电离层组合卫星端DCB改正模型,并基于MGEX跟踪站连续7天4站的观测数据按7种不同双频组合进行DCB改正实验。结果表明,DCB改正对PPP精度在最初的历元有明显提升,有助于滤波的收敛及提高单天解的均方根,但对于最终定位精度无明显提升。B2a/B3I及B2b/B3I组合定位精度及收敛速度明显低于其他组合,DCB改正后有所提升。其他5种组合改正后定位精度及收敛时间相当:静态PPP单天解均方根在E、N和U方向约为5.50 cm、2.50 cm和6.25 cm,较未改正前提升20%~65%;平均收敛时间为38 min,提升约6%;动态PPP平均收敛听语音聊科研与作者互动时间为59 min,提升约20%;最终定位精度水平方向优于5 cm,高程方向优于7 cm。

To explore the influence of BDS-3(BeiDou navigation satellite system phaseⅢ)different frequency combination satellite DCB(differential code bias)on PPP(precise point positioning),the BDS-3 different frequency ionospheric-free combined satellite DCB correction model was derived and performed DCB correction experiments by seven different dual-frequency combinations based on the observation data of four MGEX stations during seven consecutive days.The results show that the DCB correction has a significant improvement of the PPP accuracy in the initial epoch,which helped to converge the filtering and improve the RMS of the single-day solution,but weakly in the final positioning accuracy.Although the positioning accuracy of the B2a/B3I and B2b/B3I combinations′convergence speed are considerably thinner than other combinations,it still enhances after DCB correction.Otherwise,the positioning accuracy and convergence time of the other 5 combinations are equivalent after correction.The RMS of the static PPP single-day solution is about 5.50 cm,2.50 cm,and 6.25 cm in the E,N,and U directions,which are approximately 20%~65%higher than before.The average convergence time,an increase of about 6%,is 38 minutes.And the kinematic PPP,an increase of about 20%,is 59 minutes.The final positioning accuracy is better than 5 cm in the horizontal component and 7 cm in the elevation component.