区域定位系统中高程辅助三星定位算法

提出了一种不受高度限制的区域定位系统高程辅助三星定位算法.该算法既不依赖于先验的位置信息和定位结果，也不需要构建近似椭球方程.算法的关键是在牛顿算法迭代过程中不断更新接收机估算位置到地心的虚拟伪距.结合中国区域定位系统(Chinese Area Positioning System, CAPS) 的试验验证星座开展了仿真分析，结果表明：在用户高度已知的情况下，当高度达到中轨卫星轨道高度(约12×103 km)时，该算法仍能够进行正常的定位解算.在分析高程辅助算法中精度衰减矩阵的基础上，提出了高程辅助下误差椭圆轴长和轴方向的计算公式.结合CAPS试验验证星座仿真分析表明，提出的计算公式可以准确描述误差椭圆的几何特征.

Three-satellite Positioning Algorithm with Altitude Aiding for Regional Navigation Satellite System

An altitude aiding positioning algorithm not constrained by altitude was proposed for the regional navigation satellite system (RNSS). The algorithm does not require construction of the approximate ellipsoid equation or the preceding position information. The key point of the algorithm is iteratively improving the virtual range from the earth center to the estimated position in processing of Newton’s method. The virtual range is combined by the measured altitude with the approximate latitude and longitude. In order to evaluate the performance of the proposed algorithm, a simulation analysis was performed based on the Chinese area positioning system (CAPS) in the verification phase. And the results show that the proposed algorithm can provide positioning at any altitude level from the ground to medium earth orbit (about 12 000 km).With the analysis of the dilution of precision matrix for the altitude aiding algorithm, formulas of the error ellipse’s axial length and direction were proposed. The simulation results show that the formulas can describe the error ellipse geometric characteristic accurately.