BDS/GPS/Galileo多频观测值精度评估及随机模型精化

Precision estimation of the BDS/GPS/Galileo multi-frequency observations and stochastic model refining

随机模型的优劣直接影响GNSS精密定位的精度以及可靠性.通过MEGX观测网CUT0、CUT2和CUTA测站连续10 d观测数据,基于短基线单差模型方法求解各系统单差残差的时间序列,并推导出BDS/GPS/Galileo卫星观测值噪声.统计观测值噪声随高度角变化的情况,通过最小二乘拟合方法确定精化的随机模型.结果表明:Galileo的4个频点的伪距观测值精度约20~50 cm,E5频点的精度最高,E1最低,E5a和E5b基本相当;载波相位观测值精度约1~3mm,E5频点的精度明显高于E1、E5a和E5b.BDS载波观测值精度约1~3 mm,B1、B2、B3精度基本相当,其伪距观测值精度约30~50 cm,B1精度最低,B2和B3相差不多.GPS L1伪距观测值精度约63 cm,L2伪距观测值精度约42cm,载波相位精度约3 mm.基于单差模型对各系统观测值进行精度估计,在短基线情况下,BDS/GPS/Galileo载波相位观测值精度基本相当,而Galileo E5伪距观测值精度明显优于其他卫星系统伪距观测值精度.各类型卫星观测值的残差分析可为定位中随机模型的建立提供依据.

The accuracy of stochastic model directly affects the precision and reliability of GNSS precision positioning.With 10-day observation data of CUT0,CUT2 and CUTA stations in MEGX observation network,the residuals time series of GNSS were solved by single-difference model using short baseline method.According to the statistically observed noises changing with the elevation angle,a refined stochastic model is established via the least-square method.The results show that the range of pseudo-range observation precision lies in 20-50 cm,30-50 cm and 42-63 cm for Galileo,BDS and GPS,respectively;and the carrier phase observation precision falls within the scope of 1-3 mm for Galileo and BDS,and on 3 mm for GPS.For the four frequencies of Galileo,E5 is most accurate in both pseudo-range observation and carrier phase;the accuracies of B1,B2,B3 of BDS are roughly the same;the L2 of GPS is more accurate in pseudo-range observation with precision of 42 cm than L1 of 63 cm,and both L1 and L2 have carrier phase precision of 3 mm.From the above precision estimations based on single-difference model,it can be concluded that in case of short baseline,BDS/GPS/Galileo have roughly same precision in carrier phase observation values,while Galileo E5 outperforms the other satellite systems in pseudo-range observations.Residual analysis of satellite observations provides a basis for the establishment of stochastic models in positioning.