In recent years, numerous low earth orbit (LEO) satellites have been launched for different scientific tasks such as the Earth’s magnetic field, gravity recovering and ocean altimetry. The LEO satellites can cover the ocean area and are less affected by atmospheric delays and multipath errors, which provides new opportunities for calibrating the phase biases of the Global Navigation Satellite System (GNSS). In this contribution, we propose an alternative approach for uncalibrated phase delay (UPD) estimation by making full use of onboard observations of LEO satellites. Stable wide-lane (WL) and narrow-lane (NL) UPDs can be obtained from spaceborne GNSS observations and agree well with the UPD products derived from 106 IGS stations. To further verify the feasibility of the proposed method for UPD estimation, zero-difference (ZD) ambiguity resolution (AR) for precise point positioning (PPP) and LEO precise orbit determination (POD) are implemented. After applying the LEO-based UPDs, the averaged convergence time for PPP AR can be reduced to 15.2 min, with an improvement of 24% compared to float solutions. As for LEO AR, the fixing rates of WL and NL ambiguities exceed 98 and 92%, respectively. The accuracies of ambiguity-fixed orbits are validated by comparing with external satellite laser ranging (SLR) and K-band ranging (KBR) observations. Compared to float solutions, the standard deviations (STDs) of SLR residuals can be reduced by 8 ~ 43%, and the KBR residuals of 3.75 mm can be achieved for fixed solutions using LEO-based UPDs, with an improvement of 60%. Although the current UPD results derived from LEO satellites are slightly worse than those of ground-based UPD, it is anticipated that the performance of LEO-based UPD can be further improved in the near future with the rapidly increasing number of LEO satellites and the continuous refinements of the POD method.

近年来，许多低地球轨道（LEO）卫星已经发射用于不同的科学任务，例如地球磁场、重力恢复和海洋测高。LEO卫星可以覆盖海洋区域，受大气延迟和多径误差的影响较小，这为校准全球导航卫星系统（GNSS）的相位偏差提供了新的机会。在这篇文章中，我们通过充分利用 LEO 卫星的机载观测，提出了一种用于未校准相位延迟 (UPD) 估计的替代方法。可以从星载 GNSS 观测中获得稳定的宽车道（WL）和窄车道（NL）UPD，并且与来自 106 个 IGS 站的 UPD 产品非常吻合。为了进一步验证所提出的UPD估计方法的可行性，实现了用于精确点定位 (PPP) 和 LEO 精确轨道确定 (POD) 的零差 (ZD) 模糊度分辨率 (AR)。应用基于 LEO 的 UPD 后，PPP AR 的平均收敛时间可以减少到 15.2 分钟，与浮动解决方案相比提高了 24%。对于 LEO AR，WL 和 NL 歧义的固定率分别超过 98% 和 92%。通过与外部卫星激光测距（SLR）和K波段测距（KBR）观测进行比较，验证了模糊固定轨道的准确性。与浮动解决方案相比，SLR 残差的标准差 (STD) 可降低 8 ~ 43%，使用基于 LEO 的 UPD 的固定解决方案可实现 3.75 mm 的 KBR 残差，提升 60%。