低轨四星时差定位技术研究

Research of Location Technology on TODA with Four LEO Satellites

摘要:

文章重点分析影响低轨四星时差定位系统精度的主要因素;首先,从四星时差定位的基本原理出发,对四星时差定位的模型和几何精度因子进行了详细的推导,并通过仿真分析了四星构型、时差测量精度、卫星位置误差、基线长度、星座投影面积等对四星时差定位系统精度的影响；通过比较可知,在相同参数条件下,采用Y形构形,减小时差测量误差、提高卫星定位精度、增加基线长度,增大星座投影面积均等均能够提高该系统的定位精度；在低轨四星定位系统应用场景中,四星构型、卫星绝对位置测量精度、基线长度以及星座投影面积对四星时差定位系统精度影响较大,时差测量精度和卫星相对位置测量精度对四星时差定位系统精度影响较小;而在实际任务中应权衡各因素的效费比,来保证定位精度。

Abstract:

This paper mainly discusses the factors which decides the localization accuracy of TDOA with LEO four satellites. Firstly, we derive the TDOA localization model and GDOP of LEO four satellite based on the principle of TDOA. Secondly, some simulation results about factors including locations of four satellites, the accuracy of TDOA measurements, geometry of four satellites, the length of baseline, the projection area of four satellites, are demonstrated. By comparison, it is seen that one can improve the accuracy of localization by decreasing TDOA measuring errors and base station errors, increasing the length of baseline and area of projection area when using the Y geometry of four satellites. For LEO satellite application, geometry, the precision of absolute locations of four satellites,the length of baseline affect the accuracy of localization importantly, while TDOA measurement error, the precision of relative locations of four satellites effects the localization accuracy of our system minor. Therefore, we should choose these factors based on the trade-off of their accuracies and obtaining costs.