AI 中文总结
研究稀疏低地球轨道机会信号场景下双卫星多普勒精度预测与几何选择，通过验证单次过境模型、开发融合模型等方法，得出交角约20°可实现约50米理论精度且相关卫星对约30分钟内可用的结论，为卫星选择和观测调度提供指导。
AI 中文摘要
低地球轨道（LEO）卫星已成为在信号受挑战环境中定位的有前景的全球导航卫星系统（GNSS）补充。在稀疏LEO机会信号场景中，多普勒定位常仅依赖一两次卫星过境，定位精度高度依赖过境几何形状。本文研究双卫星LEO多普勒精度预测和几何选择。首先用实际铱星测量验证基于多普勒精度稀释（DDOP）框架的单次过境多普勒精度模型。接着开发信息域融合模型，结合两次卫星过境的有效位置信息并考虑过境特定时钟参数。基于此模型，推导并通过仿真验证两个预测误差椭圆的交角与融合定位精度之间的解析关系。还用长期轨道通信观测评估有利卫星对的实际可用性。结果表明约20°的交角足以实现约50米的理论定位精度，且此类互补卫星对通常在约30分钟内可用。这些结果为稀疏LEO多普勒定位中几何感知卫星选择和观测调度提供了实际指导。
英文摘要
Low Earth Orbit (LEO) satellites have emerged as a promising complement to GNSS for positioning in signal challenged environments. In sparse LEO signals of opportunity scenarios, Doppler positioning often relies on only one or two satellite passes, making positioning accuracy highly dependent on pass geometry. This paper investigates dual satellite LEO Doppler accuracy prediction and geometry selection. A single pass Doppler accuracy model based on the Doppler Dilution of Precision (DDOP) framework is first validated using real Iridium measurements. An information domain fusion model is then developed to combine the effective position information from two satellite passes while accounting for pass specific clock parameters. Based on this model, an analytical relationship between the intersection angle of the two predicted error ellipses and the fused positioning accuracy is derived and verified through simulations. Long term ORBCOMM observations are further used to evaluate the practical availability of favorable satellite pairs. Results show that an intersection angle of about 20° is sufficient to achieve approximately 50 m theoretical positioning accuracy, and that such complementary satellite pairs are typically available within about 30 min. These results provide practical guidance for geometry aware satellite selection and observation scheduling in sparse LEO Doppler positioning.
Comments12 pages,13 figures
