基于相位差测量的脉冲星时间相对导航方法

针对传统脉冲星导航方法在相位估计时依赖脉冲星信号轮廓，存在整周模糊及不确定星历参数引起的系统共模误差问题，提出基于相位差测量的脉冲星时间相对导航方法。该方法通过对脉冲星光子到达时间序列进行相位估计，以相邻时刻的相位差作为观测量，建立航天器位置增量与相位差的关系，采用广义卡尔曼滤波器处理系统噪声相关问题进行导航，可有效减小系统误差，实现脉冲星导航的应用。通过对导航系统初始定位方法、可观性分析，及基于罗西X射线时变探测器（RXTE）观测的Crab脉冲星的在轨实测数据试验分析，证明了该方法的自主性与可行性。最后，对基于相位差测量的脉冲星时间相对导航系统进行导航滤波仿真，试验结果表明，导航系统完全可观，噪声不累积，位置估计精度可满足实际应用。

Pulsar Based Time Relative Navigation Method Using Phase Difference Measurement

Aiming at the phase estimation based on pulsar signal profile, the ambiguity of the whole cycles and the impacts of the common mode error in the X-ray pulsar based navigation system, a pulsar time relative positioning method using phase difference measurement is studied. The proposed method calculates the phase of the pulsar signal from the arrival time of X-ray photons recorded by the satellite clock directly, then employs the phase difference between the two adjacent moments as the navigation measurement to establish the observation equation, and utilizes a general extended Kalman filter to deal with the correction between the process and the measurement noise. The feasibility and autonomy of the presented method are discussed by the initial orbital determination technique and the observability analysis of the corresponding navigation system theoretically, as well as an experimentation using the onboard pulse time of arrivals of the Crab pulsar observed by the Rossi X-ray timing explorer(RXTE). Finally, a navigation filtering simulation of the pulsar based time relative navigation method using phase difference measurement is studied. The results of simulations show that the navigation system is absolutely observable, the noise does not accumulate, and the accuracy of the position estimation can satisfy the demand of practical engineering.