BDS-3不同频点双频组合伪距单点定位性能分析

Performance analysis of the BDS-3 single point positioning using different dual-frequency pseudorange combinations

北斗卫星导航系统(BDS)在进行双频单点定位时通常固定使用B1I和B3I频点组合。为充分探究BDS-3系统的定位潜力,针对BDS-3不同频点双频伪距单点定位(SPP)性能展开研究。推导了卫星差分码偏差(DCB)改正公式,并建立了BDS-3任意双频组合SPP数学模型。利用全球35个多模GNSS实验(MGEX)跟踪站121 d的实测数据,采用改进的RTKLIB软件进行了全球范围内BDS-3双频无电离层组合SPP解算实验。首先,对BDS-3的6种频点信号质量进行了全面评估,包括信噪比、多路径效应和数据可用率等指标。其次,对基于DCB改正的14种BDS-3双频伪距组合进行了性能对比。研究发现,在多路径误差、信噪比及数据完整率等多项指标上,B2ab信号质量最高,B2b与B2a其次,B3I与B1C次之,B1I表现较差。在BDS-3的14种不同双频组合SPP性能比较中,基于DCB改正的定位精度明显优于未加DCB改正的情况。DCB改正相对未改正可以将三维精度由14.9~31.2 m显著减小到1.7~15.5 m。受无电离层双频组合模型噪声放大系数的影响,最优组合为B1C&B2a,最差组合为B2a&B2ab,两者数值分别为1.7 m与15.5 m。以上结论可以为BDS-3伪距定位在车载导航等方面的应用提供参考。

For dual-frequency single-point positioning(SPP)with the BeiDou navigation satellite system(BDS),the B1I and B3I frequency combination is typically used.In order to fully investigate the positioning potential of the BDS-3 system,the performance of SPP is investigated using various dual-frequency pseudorange combinations of different BDS-3 frequencies.The differential code bias(DCB)correction formula is derived,and a mathematical model for SPP positioning using any dual-frequency combination of BDS-3 is established.Using 121 days of actual data from 35 global MGEX tracking stations and an improved RTKLIB software,SPP solutions with ionosphere-free dual-frequency combinations of BDS-3 are computed globally.First,a comprehensive evaluation of the quality of six BDS-3 frequency signals is performed,including signal-to-noise ratio,multipath effects,and data availability.Then,the performance of fourteen BDS-3 dual-frequency pseudorange combinations is compared after applying DCB corrections.The study shows that the B2ab signal has the highest quality in terms of multipath error,signal-to-noise ratio,and data integrity,followed by B2b and B2a,then B3I and B1C,with B1I performing relatively poorly.Of the fourteen different dual-frequency combinations for BDS-3 SPP,the positioning accuracy after DCB correction is significantly better than that without DCB correction.Compared to the uncorrected case with a three-dimensional accuracy of 14.9 m to 31.2 m,the DCB correction improves the accuracy to 1.7 m to 15.5 m.Influenced by the noise enhencement factor of the ionosphere-free dual-frequency combination model,the optimal combination is B1C&B2a with an accuracy of 1.7 m,while the worst combination is B2a&B2ab with an accuracy of 15.5 m.These results provide a valuable reference for the implementation of BDS-3 pseudorange positioning in various fields,including vehicle navigation.