The use of X-ray pulsars for aiding navigation of satellites in constellations

An autonomous navigation technique based on X-ray pulsars for a satellite in a constellation is studied in this paper. A new method based on the pseudo-range observations from inter-satellite links together with the time difference of arrival (TDOA) measurements from pulsars is proposed to determine the absolute position of a satellite in the constellation. The extended Kalman filter (EKF) is adopted to estimate the position vectors of the satellites according to the measurements and the orbit perturbation equations. The feasibility of the proposed technique is verified by calculating the Cramer–Rao lower bound (CRLB) of the navigation system. The high performance of the method is illustrated through numerical simulations in comparison with the traditional method based on pseudo-range observations. It shows that the precision of the proposed method is better than 100 m.