基于非合作低轨卫星的测向交叉定位技术

根据非合作低轨卫星的特点，可以被动测量多颗卫星信号的来向，通过测向交叉的方式进行定位。但是通过星历解算出的卫星位置位于地心地固坐标系，用户测量的方位角和俯仰角基于站心坐标系。针对非合作低轨卫星测向交叉定位时目标用户角度信息与卫星位置基于不同坐标系的问题，提出了一种迭代最小二乘定位算法，通过迭代的方式不断收敛定位结果，能够在目标用户角度信息与卫星位置基于不同坐标系的情况下，解决非合作低轨卫星的测向交叉定位问题。仿真结果表明，基于迭代最小二乘定位算法能够实现非合作低轨卫星仅利用角度定位，并分析了测角精度、卫星轨道高度、参与定位卫星数与定位误差之间的关系。针对迭代的计算方法，分析了迭代过程中不同收敛条件下迭代次数与定位误差之间的关系。在保证定位精度的情况下，将迭代收敛范围设置为8~30 km，可以降低2~3次迭代次数。

Direction finding and cross positioning technology based on non-cooperative low Earth orbit satellite

According to the characteristics of non-cooperative low-Earth-orbit satellite, the source of multiple satellite signals can be passively measured and positioned by direction finding crossing. However, the satellite position calculated by the ephemeris solution is located in the geocentric geostationary coordinate system, and the azimuth and pitch angles measured by the user are based on the station center coordinate system. To address the problem that the target user''s angle information and the satellite position are based on different coordinate systems in the direction finding cross positioning of non-cooperative LEO satellites, an iterative least squares positioning algorithm is proposed. By iteratively converging the positioning results, the problem of direction-finding cross positioning of non-cooperative LEO satellites can be solved when the angle information and satellite positions are based on different coordinate systems. Simulation results show that iterative least squares positioning can realize non-cooperative LEO satellite positioning using only angle. And the relationship between angle measurement accuracy, satellite orbit height, the number of participating satellites and positioning error is analyzed. For the iterative calculation method, the relationship between the number of iterations and the positioning error under different convergence conditions in the iterative process is analyzed. Under the condition of ensuring the positioning accuracy, the iterative convergence range is set to 8~30 km, which can reduce the number of iterations by 2~3 times.