The Sentinel-6 Michael Freilich altimetry mission flies two GNSS receivers: a primary multi-GNSS (GPS plus Galileo) PODRIX receiver and a GPS-only TriG receiver. Each of these receivers is independently capable of supporting the precise orbit determination (POD) requirement for < 1.5 cm radial rms error. In this study, we characterize the performance of single-receiver solutions and evaluate the benefits of a combined TriG and PODRIX orbit solution. The availability of both sets of receiver observations revealed a 10 mm in-track difference between orbit solutions derived independently from TriG and PODRIX tracking data. Based on satellite laser ranging (SLR) residuals, this bias has been isolated to an apparent inconsistency between the estimated TriG receiver clock and observation time-tags of approximately 1.3 \(\mu \hbox {s}\), which is equivalent to a common range error of roughly 400 m in the TriG observations. After applying this calibration, the TriG and PODRIX displayed similar performance in terms of orbit overlap precision. PODRIX-Galileo observations showed lower code and phase tracking residual rms values compared to the GPS observations. Overall, processing the calibrated TriG and PODRIX observations separately results in highly accurate orbit solutions with radial orbit accuracies better than 1 cm rms as indicated by one-way SLR residual rms of 7.2 mm or better for each solution. Orbit solution accuracy is slightly improved by processing both TriG and PODRIX observations together, resulting in one-way SLR residual rms of 7.0 mm.

Sentinel-6 Michael Freilich 测高任务搭载两个 GNSS 接收器：一个主要的多 GNSS（GPS 加伽利略）PODRIX 接收器和一个仅 GPS 的 TriG 接收器。每个接收器都能够独立支持精确轨道确定 (POD) 要求，径向均方根误差 < 1.5 厘米。在本研究中，我们描述了单接收器解决方案的性能，并评估了 TriG 和 PODRIX 轨道组合解决方案的优势。两组接收器观测结果的可用性显示，独立于 TriG 和 PODRIX 跟踪数据得出的轨道解之间存在 10 毫米的轨道内差异。基于卫星激光测距 (SLR) 残差，这种偏差已被隔离为估计的 TriG 接收器时钟和观测时间标签之间的明显不一致，约为 1.3  \(\mu \hbox {s}\)，这相当于TriG 观测中的常见距离误差约为 400 m。应用此校准后，TriG 和 PODRIX 在轨道重叠精度方面表现出相似的性能。与 GPS 观测结果相比，PODRIX-Galileo 观测结果显示出较低的代码和相位跟踪残余均方根值。总体而言，分别处理校准的 TriG 和 PODRIX 观测结果会产生高度精确的轨道解，其径向轨道精度优于 1 cm rms，如每个解的单向 SLR 残余 rms 为 7.2 mm 或更好所示。通过同时处理 TriG 和 PODRIX 观测结果，轨道解算精度略有提高，单向 SLR 残差 rms 为 7.0 mm。