| 摘要: |
| 低轨（LEO）卫星的轨道高度低，落地信号强，其快速运动导致的几何构型变化显著提高了模糊度参数的可估性，进而改善了精密单点定位（PPP）的精度和收敛速度。针对难以利用地面跟踪数据解算LEO卫星的轨道钟差的现状，基于LEO星载全球卫星导航系统（GNSS）观测值进行轨道与钟差解算。在对地面站进行PPP时，为每颗LEO卫星增设一个使用常数（CON）模型或随机游走（RWK）模型进行估计的偏差参数，以模型化由硬件延迟差异引起的钟差偏差。4个测站的实验结果表明，加入90颗LEO卫星的观测数据时，两种模型对PPP收敛速度的提升性能相近。在东（E）、北（N）及垂直（U）3个方向的定位精度提升方面，RWK模型整体优于CON模型。相较于加入30或60颗LEO卫星的观测数据，加入90颗LEO卫星的观测数据显著提高了收敛速度和定位精度。在90颗LEO卫星的情况下，4个测站的收敛速度提升差异较大，E，N，U这3个方向的定位精度分别提高了48.3%，43.4%和40.8%。 |
| 关键词: 精密单点定位 低轨导航增强 低轨卫星下行信号 常数模型 随机游走模型 北斗卫星导航系统 |
| DOI： |
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| 基金项目:国家自然科学基金青年科学基金（42404019）；国家自然科学基金面上项目（42474023） |
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| Performance analysis of LEO satellite augmented BeiDou precise point positioning |
| ZHAO Wenxuan,ZHANG Zhongying,ZHANG Keke,DENG Zhixu,YANG Jianhua,LI Mingzhe |
| (School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China;School of Electronic Information, Wuhan University, Wuhan 430079, China; China Satellite Network System Institute Co., Ltd., Beijing 100070, China) |
| Abstract: |
| Low Earth orbit (LEO) satellites are distinguished by their low orbital altitude and strong ground signal. Due to their high-speed motion, they undergo rapid geometric configuration changes, which significantly enhances the estimability of ambiguity parameters and improves the accuracy and convergence speed of precise point positioning (PPP). Due to the difficulties of using ground tracking data to determine the orbit and clock offsets of LEO satellites, this determination is performed based on LEO satellite-borne GNSS observations. During PPP processing for ground stations, an additional bias parameter is introduced for each LEO satellite, estimated by either a constant (CON) model or a random walk (RWK) model, to model the clock offset biases caused by hardware delay discrepancies. Experimental results from four stations indicate that incorporating observations from 90 LEO satellites leads to both models demonstrating comparable performance in enhancing PPP convergence speed. The RWK model is superior to the CON model in improving positioning accuracy in the east (E), north (N), and vertical (U) directions. Compared with incorporating observation data from 30 or 60 LEO satellites, the incorporating observation data from 90 satellites achieves significant improvements in both convergence speed and positioning accuracy. Under the 90-satellite configuration, distinct enhancements in convergence speed are observed across the four stations, with maximum accuracy improvements reaching 48.3%, 43.4%, and 40.8% in the E, N, and U components, respectively. |
| Key words: Precise point positioning (PPP) Low Earth orbit (LEO) navigation augmentation LEO satellite downlink signals Constant model Random walk model BeiDou navigation satellite system (BDS) |
