北斗三号卫星差分码偏差稳定性分析及其对单点定位的影响

Stability Analysis of BDS-3 Satellite Differential Code Bias and Its Impacts on Single Point Positioning

差分码偏差(differential code bias,DCB)是影响电离层监测和导航定位精度的重要因素之一,建立DCB改正模型对高精度定位有重要意义。针对北斗三号卫星的广播星历和精密星历钟差参数时间基准不统一的问题,首先介绍了多星座实验(multi-GNSS experiment,MGEX)发布的DCB产品的估计方法,给出了部分DCB产品的精度评估和分析结果;然后提出了北斗三号卫星单频和双频伪距单点定位以及双频精密单点定位的DCB改正模型;最后利用5个MGEX测站连续5 d的实测数据分别进行了DCB改正前后的定位实验。结果表明,MGEX发布的DCB产品均具有较高的稳定性,经卫星DCB改正后,单频和双频伪距单点定位的定位精度分别提高了48%~85%和71%~91%,双频静态精密单点定位的收敛时间减少了56%~83%。

Objectives: Differential code bias(DCB) is one of the important factors affecting the accuracy of ionospheric monitoring and high-precision positioning. The establishment of DCB correction model is of great significance for high-precision positioning.Methods: Aiming at the problem that the BDS-3 satellite clock time references of broadcast ephemeris and precise ephemeris are not uniform, firstly, we introduce the DCB estimation methods of Chinese Academy of Sciences(CAS) and German Aerospace Center(DLR), and give the accuracy evaluation and analysis results of some DCB products. Secondly, the DCB correction models of BDS-3 single-frequency and dual-frequency standard point positioning(SPP), dualfrequency precise point positioning(PPP) are proposed. Finally, both SPP and PPP experiments are carried out with different schemes by using five-day measured data of the multi-GNSS experiments(MGEX) stations.Results: The results show that the MGEX DCB products have high stability. And the accuracies of single-frequency and dual-frequency SPP are increased by 48%—85% and 71%—91% after using DCB correction, respectively. The convergence time of dual-frequency static PPP is reduced by 56%—83% after using DCB correction.Conclusions: It can be concluded that the satellite DCB correction can improve the SPP positioning accuracy and reduce the PPP convergence time.