GPS卫星P1-C1码间偏差对星基增强改正数计算的影响分析

为分析GPS卫星P1-C1码间偏差对星基增强改正数计算的影响，利用中国广域分布监测站的GPS C1-P2双频实测数据计算GPS卫星钟差和星历改正数，并将其用于定位实验。实验结果表明，GPS卫星P1-C1码间偏差修正前后的卫星钟差改正数计算结果差异较为明显。定位结果表明，在SBAS改正数计算和用户定位时均对卫星P1-C1码间偏差进行修正，可使GPS C1码单频SBAS用户95%三维定位误差降低约19%，其中水平误差由1.94 m降低至1.45 m，高程误差由3.82 m降低至3.14 m；对于GPS C1-P2双频SBAS用户，只要保证在SBAS定位时对观测量中卫星P1-C1码间偏差的处理与SBAS改正数计算时一致，就可消除卫星P1-C1码间偏差的影响。

Impact Analysis of P1-C1 Differential Code Biases of GPS Satellites on SBAS Corrections Estimation

In order to analyze the impact of the GPS satellite P1-C1 differential code biases(DCB) on the estimation of satellite-based augmentation system(SBAS) corrections, GPS C1-P2 dual-frequency measurements of the monitoring stations in mainland China are used to generate the GPS SBAS clock-ephemeris corrections and the corrections are used in a standard positioning test. According to the results, there are significant differences between the estimated satellite clock corrections with and without P1-C1 biases. The positioning results show that taking off the P1-C1 DCB during the SBAS corrections estimation and SBAS users positioning can reduce the GPS C1 code SBAS users 95% positioning errors from 1.94 m to 1.45 m and from 3.82 m to 3.14 m in the horizontal and vertical directions, respectively, indicating a 19% reduction in three-dimensional positioning errors compared to those not taking off the biases. For C1-P2 dual-frequency SBAS users, the P1-C1 DCB impact can be eliminated as long as the processing of P1-C1 DCB in users positioning is consistent with the SBAS corrections estimation.