北斗卫星伪距偏差标定及对用户定位精度影响

伪距偏差是指卫星导航信号非理想特征导致的不同技术状态接收机产生的伪距测量常数偏差。本文将伪距偏差作为一种用户段误差，提出基于并置接收机的伪距偏差计算方法和基于DCB参数的伪距偏差计算方法，以实现伪距偏差与其他误差的分离。然后利用实测数据测量了北斗卫星伪距偏差，结果表明伪距偏差标定序列波动STD约为0.1 m，不随时间明显变化，不同地点接收机测量的伪距偏差具有较好的一致性。在1.5 G频段，北斗卫星B1I频点伪距偏差最大。北斗卫星新体制信号B1C伪距偏差最小，较北斗卫星B1I频点伪距偏差明显改善，也明显好于GPS卫星L1C/A频点伪距偏差。在其他频段，GPS卫星L2C伪距偏差略大于北斗卫星B3I伪距偏差，L5C频点伪距偏差次之，B2a频点伪距偏差最小。最后，利用实测数据分析了伪距偏差对定位精度的影响。结果表明伪距偏差与卫星群延迟参数高度相关。若用户接收机与群延迟参数计算采用的接收机技术状态差异较大，用户接收机定位精度将明显恶化。

Characterization of pesudorange bias and its effect on positioning for BDS satellites

Distortions of GNSS signals result in pesudorange biases. The biases are different for different receivers depending on frontend bandwidth and employed filters of receivers. Pesudorange biases are treated as a new error sources in this paper. Firstly, two pesudorange bias calibration calculation methods namely collocated receivers-based method and differential code bias (DCB) based method are proposed to separate pesudorange biases and other error sources. Then pesudorange biases are calculated, estimated and separated from other error sources using collocated receivers-based method. The STD of BDS estimated pesudorange biases series is approximately 0.1 m. The BDS estimated pesudorange biases keep constant with time. Pesudorange biases are also irrelevant with geographical locations of receivers. At 1.5 G band, B1I pesudorange bias is the largest. The pesudorange biases of BDS new signal B1C improve a lot compared with pesudorange biases of BDS B1I and are also much better than the GPS L1C/A. At other bands, pesudorange biases of GPS L2C are slightly larger than BDS B3I, followed by GPS L5C, pesudorange biases of BDS B2a are the smallest. The influence of pesudorange biases is also analyzed with measurements. Pesudorange biases are highly-correlated with total group delay (TGD). If the user receivers are quite different with those used for TGD calculation, the positioning accuracy will get worse.