Earth-Based Radar Asteroid 2D Imaging Technology Based on Rotation Measurement

Synthetic aperture technology is a very important astrometric method. As humanity continues to explore the universe, the issue of low signal-to-noise ratio (SNR) presents significant challenges for earth-based astronomical radar imaging. This is especially true when observing asteroids, as their rapid and unknown rotation speeds lead to traditional sub-aperture integration methods not only failing to improve SNR but even further deteriorating image quality. In view of this, this paper proposes a full coherent imaging method based on the search for the rotation period of asteroids. First, a set of sub-aperture image sequences can be obtained using the delay-Doppler algorithm. Second, scene grids are divided at the target, assuming an unknown rotation period as a pending parameter. Then, this paper derives the RD positioning model formula under rotating scenes, resamples different sub-apertures, and precisely compensates the phase. Next, the different sub-aperture images are coherently integrated and the image entropy is calculated. Finally, the above steps are iteratively repeated until the optimal rotation parameters and imaging results are obtained. Computer simulations verify the effectiveness of the algorithm proposed in this paper.