低轨导航星座多普勒定位模型及性能分析

DOPPLER POSITIONING MODEL AND PERFORMANCE ANALYSIS OF LEO CONSTELLATION

相较于北斗、GPS等全球卫星导航系统(GNSS),低轨道卫星(LEO)具有更加显著的多普勒频移效应,有助于增强GNSS定位、导航和授时(PNT)服务性能。针对当前可用的LEO导航信号少,无法满足地面用户瞬时定位的问题,研究提出了基于一个由288颗LEO卫星构成的Walker星座,选取仿真了9个全球均匀分布的地面站多普勒观测值,建立了瞬时多普勒定位数学模型,并评估了其潜在的服务性能。结果表明:在中低纬度地区,LEO可视卫星为10~15颗左右,多普勒定位精度因子(PDOP)达到500~600;而在中高纬度地区,LEO可视卫星数达到30颗以上,对应的PDOP值降至180左右。静态多普勒定位可实现厘米至分米级精度,动态定位可实现瞬时分米至米级精度,高纬度地区的定位性能显著优于中低纬度地区。

To provide backup and supplementation for the global navigation satellite system(GNSS),Doppler shift from low earth orbit(LEO)satellites can be used as the signals of opportunity to provide positioning,navigation,and timing(PNT)service.This paper mainly investigates the LEO instantaneous Doppler positioning model and evaluates the positioning performance in different scenarios.Given a LEO constellation with 288 satellites,we first simulate Doppler shift observations at nine stations.The results show that in the middle and low latitudes,the number of LEO visible satellites is about 10~15,and the Doppler position dilution of precision(PDOP)reaches 500~600,while in the middle and high latitudes,the number of LEO visible satellites reaches more than 30,and the corresponding PDOP value decreases to about 180.Static LEO Doppler positioning results show that an accuracy of centimeter to decimeter level can be achieved after a period of convergence.For static simulated kinematic positioning test,the RMSEs range from a few decimeters to several meters at different regions by giving different constraints.