A new pulse time-of-arrival estimation method for X-Ray pulsar navigation

Abstract

X-ray pulsar navigation (XPNAV) is an important technology for long time and high precious spacecraft autonomous navigation. XPNAV system can offer position, velocity and accurate time navigation information for spacecraft in near-earth orbit, geostationary orbit, elliptic orbit or interplanetary orbit. XPNAV has an extremely important military use and wide application prospect. In XPNAV system, pulse time-of-arrival (TOA) is a basic observation, and its estimation precious decides the precious of XPNAV’s timing and position determination, thus high precious pulse TOA estimation is an important technology in XPNAV system. To improve the pulse TOA estimation precious of XPNAV system, we proposed a pulse TOA estimation method based on correlation information. First, based on the time observation data of photons radiating for X-ray pulsar to the spacecraft, the pulse folding profile is obtained by epoch folding. Then, we constructed the new observation equation by analyzing the correlation result between the folding profile and normal profile. At last, eigen-decomposed the new observation equation we can obtain two mutually orthogonal feature vectors, so the pulse TOA can be estimated by the orthogonal property of the two vectors. Simulation results show the validity of the proposed methods, and can improve the TOA estimation precious compared with the traditional correlation method.