Solar-direct/planet-reflected light TDOA estimation method against time dispersion effects

Abstract The solar TDOA (Time Difference of Arrival) navigation is on the status of feasibility research. The goal of this paper is to analyze its feasibility from the perspective of the accuracy of estimation. The time dispersion effects arising from the solar sphere lead to the distortion of the planet-reflected light profile, which results in the sharp decline of the accuracy of TDOA. To solve this problem, we research the formation mechanism of the planet-reflected profile, and develop the solar-direct/planet-reflected light TDOA estimation method against time dispersion effects. In this method, two high-speed cameras placed at the spacecraft observe the Sun and the planet, and obtain the solar sequence images and the planet-reflected light profile, respectively. We transform the solar sequence images into the spread sub-profiles. And then these sub-profiles are shifted and superposed to construct the planet-reflected profile. Compared the observed planet-reflected profile with the constructed one, the solar TDOA is obtained by the time-of-arrival estimation for mutual power spectrum. Due to the lack of the celestial data including the actual planet-reflected profile and the solar video with super-high frame frequency, we theoretically analyze the variance consistency law of the superposed solar light profile, and simulate the virtual spread sub-profiles. Simulation results demonstrate that the solar-direct/planet-reflected light TDOA estimation method is immune to time dispersion effects, and its accuracy achieves the order of 1 km.