An analysis of X-ray pulsar navigation accuracy in Earth orbit applications

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. (C) 2021 COSPAR. Published by Elsevier B.V. All rights reserved.