LEO 卫星TDOA/DOA 定位性能分析

Analysis of LEO satellite TDOA/DOA positioning performance

随着以“星链”卫星为代表的低轨(LEO)互联网卫星系统的快速发展,星载相控阵列天线的应用数量飞速增长,未来LEO互联网卫星便于提供星载电磁波到达方向(DOA)检测能力。卫星覆盖区内的非法干扰进行定位排查,是未来互联网卫星系统正常运维的重要保障。目前常用的双星到达时差(TDOA)/到达频差(FDOA)定位体制存在定位误差显著增大的“定位盲区”造成盲区内的干扰源无法定位的问题,提出了一种基于加权最小二乘约束优化模型的TDOA/DOA双星干扰源定位技术体制。分析了几何稀释精度因子(GDOP)的定位误差,仿真实验表明该定位方法具有不存在“定位盲区”的优点,在经纬度张角为4∘×4∘的波束范围内定位误差小于0.2 km,定位误差的地理平均为0.112 km,满足非法干扰定位排查的应用需求。通过定位解算的根均方差(RMSE)的蒙特卡洛方法,验证了GDOP误差精度。该定位方法的定位误差地理稳定性优于目前常规的双星TDOA/FDOA定位算法。

With the rapid development of Low Earth Orbit(LEO)Internet satellite systems represented by“Star Link”,the number of applications of spaceborne phased array antennas has grown rapidly.In the future,LEO Internet satellites are easy to provide space-borne electromagnetic wave direction of arrival(DOA)detection capabilities.Positioning and investigation of illegal interference in the coverage area of the satellite is an important guarantee for the normal operation and maintenance of the future Internet satellite system.At present,the commonly used TDOA/FDOA positioning system has the problem that the interference source in the blind area cannot be located due to the“positioning blind area”where the positioning error increases significantly.This paper proposes a TDOA/DOA dual-satellite interference source positioning technology system based on the weighted least squares constraint optimization model.The positioning error of geometric dilution of precision factor(GDOP)is analyzed.The simulation results show that the positioning method has the advantage of no“blind spot”.The positioning error is less than 0.2 km in the beam range of 4∘×4∘latitude and longitude,and the geographical average of positioning error is 0.112 km,which meets the application requirements of illegal interference positioning and troubleshooting.The accuracy of GDOP error is verified by the Monte Carlo method of root mean square error(RMSE).The geographical stability of the positioning error of this positioning method is better than that of the conventional two-satellite TDOA/FDOA positioning algorithm.