地理坐标系下GPS定位误差的定量研究

针对目前对使用伪距的GPS定位误差的定量分析仍然不够精确的问题，本文分2种情况在东北天地理坐标系下对GPS定位误差进行了进一步分析:当使用全部可见卫星进行定位时，通过为不同纬度设置相应参数明显改进了GPS定位误差表达式；当选择4颗最优卫星进行定位时，针对更加实际的情况首次得出了GPS定位误差表达式. 从而给出了这2种情况下各向定位误差之间的关系. 在用户测距误差标准差σ_URE已知的情况下，根据提出的公式能够更加准确地估计GPS各向定位误差的标准差. 通过SPIRENT卫星信号模拟器生成赤道、北纬45°和北极点处的卫星信号，验证了所提出公式的精确性. 

Quantitative Research on GPS Position Errors in an East-North-Up Coordinate System

The current quantitative analysis of GPS position errors using pseudoranges is still not accurate enough. Therefore, in this paper, GPS position errors in an east-north-up local topocentric coordinate system were further analysed in two scenarios. Firstly, using all visible satellites for positioning, the expressions of GPS position errors were modified by setting corresponding parameters for different latitudes. Secondly, four optimum satellites were selected for positioning, the expressions for GPS position errors were first derived for a more practical situation. On this basis, the interrelationships between various position errors were established for the above two scenarios, respectively. It was designed that, if the standard deviation of a user ’s pseudorange error σ_URE was known, the standard deviations of GPS position errors could be estimated more accurately according to the proposed formulas. The accuracy of the proposed formulas was verified using a SPIRENT satellite signal simulator, generating realistic satellite signals at the equator,45° north latitude and the north pole respectively.