Single-difference (SD) ambiguity resolution (AR) and track-to-track (T2T) AR are two typical AR methods in precise orbit determination (POD) for Low Earth Orbit (LEO) satellites, which could improve the accuracy of orbits greatly. In this study, SD AR and T2T AR methods are introduced and analyzed. The performance of these two methods is assessed by three months of GPS observations from the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) twin satellites. Results show that T2T AR is highly dependent on the stability of receiver hardware delays, while SD AR requires Fractional Cycle Bias (FCB) or Integer Recovery Clock (IRC) products. We find that these two methods have comparable performance in Reduced Dynamic Precise Orbit Determination (RDPOD), while SD AR slightly outperforms T2T AR in Kinematic Precise Orbit Determination (KPOD). We also find that SD AR has a higher AR success rate than T2T AR. Therefore, we recommend SD AR as the top choice in LEO orbit determination, and T2T AR can be a good alternative when FCB or IRC products are not available.

在低地球轨道（LEO）卫星的精确轨道确定（POD）中，单差（SD）模糊度分辨率（AR）和轨到轨（T2T）AR是两种典型的AR方法，可以大大提高轨道精度。在这项研究中，SD AR和T2T AR方法被介绍和分析。这两种方法的性能是通过重力恢复和气候实验跟踪（GRACE-FO）双卫星进行的三个月GPS观测评估的。结果表明，T2T AR高度依赖于接收机硬件延迟的稳定性，而SD AR需要分数周期偏差（FCB）或整数恢复时钟（IRC）产品。我们发现这两种方法在动态精确定轨（RDPOD）方面具有可比的性能，而SD AR在动态精确定轨（KPOD）中略胜于T2T AR。我们还发现，SD AR的AR成功率比T2T AR高。因此，我们建议将SD AR作为LEO轨道确定的首选，当FCB或IRC产品不可用时，T2T AR可能是一个不错的选择。