At present, studies on X-ray signal processing and the navigation filtering algorithm in X-ray pulsar navigation are largely independent; thus, navigation accuracy analysis must be based on the analysis of a sound and complete navigation system. In this study, a navigation system simulation initiated from the numerical generation of the observed signals to navigation filtering solutions was established on the basis of the requirements of the authenticity and integrity of a demonstration of Earth-orbit spacecraft navigation. The influences of the navigation observation time, time delay estimation algorithms, and different pulsar combinations imposed on navigation accuracy were therefore analyzed. The simulation results showed that an optimal observation time existed with the highest navigation accuracy in Earth-orbit applications when three pulsars were observed in parallel, thereby obtaining the optimal observation time and its corresponding navigation accuracy. Using the short time high-accuracy algorithm of time delay estimation, the navigation accuracy of low-orbit spacecraft was greatly improved by 1010 m when the observation time was 60 s. Among three combinations of pulsars analyzed in this study, the pulsar combination of PSR B0531+21, PSR B1821-24, and PSR B1937+21 achieved the highest navigation accuracy on a low orbit, whose result was 560 m. The corresponding simulation results were based on a complete and near-real navigation algorithm, thereby offering a theoretical foundation for determining the navigation accuracy and selecting the orbit and observation time parameters in Earth-orbit pulsar navigation applications.

目前，X射线脉冲星导航中X射线信号处理和导航滤波算法的研究在很大程度上是相互独立的；因此，导航精度分析必须建立在对一个健全、完整的导航系统的分析的基础上。本研究根据地球轨道航天器导航演示的真实性和完整性要求，建立了从观测信号的数值生成到导航滤波解的导航系统仿真。分析了导航观测时间、时延估计算法和不同脉冲星组合对导航精度的影响。仿真结果表明，在地轨应用中，并行观测三颗脉冲星时，存在导航精度最高的最优观测时间，从而得到最优观测时间及其相应的导航精度。采用时延估计的短时高精度算法，在观测时间为60 s时，低轨航天器的导航精度大大提高了1 010 m。在本研究分析的三种脉冲星组合中，PSR B0531+21、PSR B1821-24和PSR B1937+21脉冲星组合在低轨道上的导航精度最高，导航精度为560 m。相应的仿真结果基于完整且接近真实的导航算法，