基于双频GPS观测的简化动力学最小二乘批处理精密定轨

星载双频GPS载波相位和伪距观测量已成为低轨卫星获取精确三维位置和速度信息的主要方式. 本文以非差消电离载波相位和伪距组合作为观测量，应用简化动力学最小二乘批处理方法进行地球低轨卫星的精密定轨，并给出完整定轨流程. 采用逐段常量的经验加速度对动力学模型误差进行补偿，描述了经验加速度敏感矩阵及稀疏带状矩阵求逆的有效计算方法. 利用GRACE-A卫星GPS观测数据对定轨位置精度进行分析，结果显示，三维位置定轨精度优于5cm，经验加速度在径向、切向和法向上的补偿水平不超过40nm·s^-2，大气阻力系数和辐射光压系数的估计值符合物理实际，星载接收机钟差大致呈线性并具有短周期小波动.

Precise Orbit Determination Based on Reduced Dynamic Batch LSQ Estimation Method Using Dual-frequency GPS Observations

The dual-frequency GPS carrier phase and pseudorange measurements have become the primary observations for accurately determining the position and velocity of satellites in low Earth orbit (LEO). Reduced dynamic batch least squares (LSQ) technique is used for LEO orbit determination using pseudorange and carrier phase ionosphere-free measurements, which combines the merits of kinematic positioning technique with pure dynamic orbit determination. In order to compensate for any unmodelling or inaccuracy of the employed dynamic model, piece-wise constant accelerations are estimated in consecutive subintervals on the basis of a precise deterministic force model in the batch LSQ method. Particularly, the paper introduces two methods for calculating the sensitive matrix related to empirical accelerations and solving for the inverse of a banded sparse matrix. GRACE-A real flight data has been used to evaluate the positioning performance of the proposed method. Positioning accuracy of less than 5cm in terms of 3D RMS was achieved. The magnitudes of empirical accelerations were all less than 40nm·s-2 in radial, along-track and cross-track directions. The extra dynamic parameters C_D and C_R were estimated within a reasonable range and the space-borne receiver's clock offset was linear with small periodic fluctuations.