VTWSAR: A Fast Calculation Method for Visible Time Window of SAR Satellite to Regional Target

The calculation of the visible time window (VTW) of synthetic aperture radar (SAR) satellite to regional target plays an important role in SAR satellite mission planning. At present, the VTW calculation for regional target mainly uses the grid point approach, which faces the problem of high spatial and temporal computational complexity. In addition, the current VTW calculation method is mainly designed for optical satellite, without considering the imaging characteristics of SAR satellite. To address the above problems, this study proposes a fast VTW calculation method for SAR satellite to regional target. First, a fast orbit filtering method for regional target is proposed based on a joint simplified visible field, which reduces a large amount of irrelevant orbit calculations. Then, a fine VTW calculation method is proposed based on the boundary intersection judgment of the projection plane and time dichotomy, which reduces both the space complexity and the time complexity. Finally, a SAR satellite VTW calculation model including 2-D steering is constructed, and the VTW calculation method is expanded to different SAR satellite imaging modes. The simulation experiment is conducted using six SAR satellites and nine regional targets. Compared with the professional software STK, the proposed method can improve the calculation efficiency by two times, and the average calculation error is 0.015 s, which proves the effectiveness of the proposed algorithm, and experimental verification is carried out on the SmartSat-X1 satellite, the measured data results confirm the effectiveness of the proposed method.