BDS-3单频三种差分定位方法的性能初步评估

Preliminary evaluation of three differential positioning methods of BDS-3 single frequency

为进一步分析北斗三号全球卫星导航系统(BDS-3)B3I、B1C、B2a和B1I单频差分定位精度,利用全球14个MGEX测站构成基线长度在30km以下的7条基线2022-09-01到2022-09-30共30d观测数据,在评估可视卫星数和信噪比基础上,初步评估了BDS-3B3I、B1C、B2a和B1I单频伪距差分、载波平滑伪距差分和载波相位差分定位精度。结果表明:数据质量方面,BDS-3B3I、B1C、B2a和B1I可见卫星数和信噪比基本符合解算需求;差分性能方面,B1C和B2a相当,B3I和B1I略差;伪距差分E、N、U方向优于0.6m,点位精度优于0.8m,单频平滑效果B1C优于B3I、B1I和B2a,在E、N、U方向分别平均提升21.34%、22.2%和17.17%。设置平滑值和原始伪距阈值定位精度得到较好的提升;BDS-3载波相位差分B3I定位精度优于7 cm,B1C定位精度优于5 cm,B2a定位精度优于6 cm,B1I定位精度优于5cm。总体定位精度随着基线长度逐渐下降,单频伪距差分定位精度达到分米级,载波平滑伪距中短基线定位精度相较于伪距差分能够提升40%,长基线提升20%,载波相位差分为用户提供厘米级定位精度。

To further analyze the accuracy of BeiDou-3 global navigation satellite system(BDS-3)B3I,B1C,B2a,and B1I single frequency differential positioning,a total of 30 days of observation data from 7 baselines with a baseline length below 30 km,consisting of 14 MGEX stations worldwide,were used from 2022-9-1 to 2022-9-30.Based on the evaluation of the number of visible satellites and signal-to-noise ratio,the accuracy of BDS-3 B3I,B1C,B2a,and B1I single frequency pseudo range differential positioning,carrier smooth pseudo range differential positioning,and carrier phase differential positioning were preliminarily evaluated.The results show that in terms of data quality,the number of visible satellites and signal-to-noise ratio of BDS-3 B3I,B1C,B2a,and B1I basically meet the calculation requirements;In terms of differential performance,B1C and B2a are comparable,while B3I and B1I are slightly inferior;The pseudo range difference is better than 0.6 m in the E,N,and U directions,with a point accuracy of better than 0.8 m.The single frequency smoothing effect B1C is better than B3I,B1I,and B2a,with an average improvement of 21.34%, 22.2%, and 17.17% in the E, N, and U directions, respectively. The positioning accuracy is improved significantly by setting smoothing values and the original pseudo range threshold;The BDS-3 carrier phase difference B3I positioning accuracy is better than 7 cm, B1C positioning accuracy is better than 5 cm, B2a positioning accuracy is better than 6 cm, and B1I positioning accuracy is better than 5cm. The overall positioning accuracy gradually decreases with the length of the baseline, and the single frequency pseudo range differential positioning accuracy reaches the decimeter level. The carrier smooth pseudo range medium and short baseline positioning accuracy can be improved by 40% compared to pseudo range differential, and the long baseline can be improved by 20%. The carrier phase differential provides users with centimeter level positioning accuracy.