北斗系统差分码偏差解算中一种新的定权方法

A Method of Determining the Weight Matrix for BDS DCB Resolution

差分码偏差（DCB）参数是影响用户定位、导航、授时和电离层求解的重要误差源之一。分析了北斗卫星导航系统不同轨道卫星高度角与不同频点信噪比（SNR）差值间的关系。实验分析表明：不同轨道卫星间信噪比差值具有较大差距,IGSO卫星信噪比差值（DSNR）较小且较为稳定,明显优于其他卫星;GEO卫星信噪比差值变化较小但绝对值较大;MEO卫星变化频繁且幅度较大。针对北斗系统具有多种轨道卫星的特点,结合卫地距与不同频点信噪比差值,提出了一种新的定权公式,并系统分析了不同定权方式下卫星DCB解算结果。实测数据分析表明：新的定权公式可以提高DCB解算精度,增强解算结果的稳定性。其中对于B1,B2和B1与B3差分码偏差,GEO卫星分别提高1%-15%和9%-16%;IGSO卫星提高4.5%-16%和8%-9%;MEO卫星提高20%-22%和27%-28%。

The differential code bias（ DCB） in global navigation satellite system（ GNSS） satellites should be precisely determined using real ground GNSS data when designing certain applications, such as precise positioning,navigation and timing. This paper analyzed the relationship between satellite elevation angle with difference SNR（ signal to noise ratio） of BDS（ Bei Dou Satellite Navigation System） different orbital satellite. The experimental results showed that the SNR difference of IGSO satellite was smaller and more stable, much better than other satellites; the change of GEO satellite SNR difference（ DSNR） was small, but the absolute value was large; MEO satellite SNR difference changed frequently and big. A new algorithm to get the BDS observation weight was introduced by considering the distance between the satellite and the Earth and SNR difference. The results indicated that the new weight algorithm improved the accuracy and enhanced the stabilities of DCB12 and DCB13, which improved GEO satellites 1% - 15% and 9% - 16%, IGSO satellites 4. 5% - 16% and 8% - 9%, MEO satellites20% - 22% and 27% - 28%.