The European Space Operations Centre currently operates five Copernicus Sentinel satellites in the framework of Europe’s Copernicus Earth observation programme. The routine operations rely on a daily orbit determination, carried out on-ground, consisting in a least-squares fit of a dynamical model to GPS navigation solutions generated on-board. The purpose of this paper is the estimation of realistic uncertainties on this daily determined state vector. By comparison with the orbit derived by Precise Orbit Determination, we estimate the 1-sigma errors at approximately 0.5m and 0.5mm/s. Non-stationary errors in the navigation solution preclude their characterisation with a constant covariance matrix. Error whitening is achieved by decreasing the signal-to-noise ratio in the errors through the use of underestimated weights on the data. The approach keeps the errors on the derived state vector unchanged and allows the covariance on the state vector to become realistic.

中文翻译：

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基于 GPS 的运行轨道确定的不确定性：Sentinel-1 和 Sentinel-2 卫星的案例研究

欧洲空间运营中心目前在欧洲哥白尼地球观测计划的框架内运行五颗哥白尼哨兵卫星。常规操作依赖于在地面进行的每日轨道确定，包括动态模型与机载 GPS 导航解决方案的最小二乘拟合。本文的目的是估计这个每日确定的状态向量的实际不确定性。通过与通过精确轨道确定得出的轨道进行比较，我们估计 1-sigma 误差约为 0.5m 和 0.5mm/s。导航解决方案中的非平稳误差排除了使用恒定协方差矩阵对其进行表征的可能性。错误白化是通过使用低估的数据权重来降低错误中的信噪比来实现的。