针对新一代海洋水色观测卫星海岸带成像仪(coastal zone imager,CZI)需在海岸带区域实现高分辨率、高信噪比、大动态范围、大幅宽和多谱段探测等需求,以及体积小、质量小等约束条件,开展了CZI的设计与验证工作。首先,设计了大范围、高...针对新一代海洋水色观测卫星海岸带成像仪(coastal zone imager,CZI)需在海岸带区域实现高分辨率、高信噪比、大动态范围、大幅宽和多谱段探测等需求,以及体积小、质量小等约束条件,开展了CZI的设计与验证工作。首先,设计了大范围、高精度指向机构,通过摆镜组件扩大可视范围,以获取大幅宽范围内的海岸带观测图像。提出了透射与反射比可控的视场复用成像设计方法,实现了光机主体结构轻小型化。其次,设计了多谱段交错布局,提高了海岸带区域9个谱段探测的配准精度。然后,提出了“外+内”嵌套式两级消杂光方案,有效抑制杂散光的传播途径,在大视场范围内实现优于2%的低杂光性能,从而提升海岸带成像质量。最后,进行了地面验证、视轴指向精度、杂光抑制及在轨成像性能等测试,完成了在轨成像质量评价。测试结果表明:轻小型、大幅宽及多谱段的新一代CZI能够在1029 km宽幅范围内对海岸带区域进行高精准指向探测,具备全色优于5 m、多光谱优于20 m的高分辨率海岸带多光谱探测能力,实现了9谱段高信噪比和大动态范围成像,显著提升了全球海陆交界范围内信息获取的效能。展开更多
Spaceborne Synthetic Aperture Radar(SAR) is a well-established and powerful imaging technology that can provide high-resolution images of the Earth’s surface on a global scale. For future SAR systems, one of the key ...Spaceborne Synthetic Aperture Radar(SAR) is a well-established and powerful imaging technology that can provide high-resolution images of the Earth’s surface on a global scale. For future SAR systems, one of the key capabilities is to acquire images with both high-resolution and wide-swath. In parallel to the evolution of SAR sensors, more precise range models, and effective imaging algorithms are required. Due to the significant azimuth-variance of the echo signal in High-Resolution Wide-Swath(HRWS) SAR, two challenges have been faced in conventional imaging algorithms. The first challenge is constructing a precise range model of the whole scene and the second one is to develop an effective imaging algorithm since existing ones fail to process highresolution and wide azimuth swath SAR data effectively. In this paper, an Advanced High-order Nonlinear Chirp Scaling(A-HNLCS) algorithm for HRWS SAR is proposed. First, a novel Second-Order Equivalent Squint Range Model(SOESRM) is developed to describe the range history of the whole scene, by introducing a quadratic curve to fit the deviation of the azimuth FM rate. Second, a corresponding algorithm is derived, where the azimuth-variance of the echo signal is solved by azimuth equalizing processing and accurate focusing is achieved through a high-order nonlinear chirp scaling algorithm. As a result, the whole scene can be accurately focused through one single imaging processing. Simulations are provided to validate the proposed range model and imaging algorithm.展开更多
基金supported by the National Natural Science Foundation of China (No. 61861136008)。
文摘Spaceborne Synthetic Aperture Radar(SAR) is a well-established and powerful imaging technology that can provide high-resolution images of the Earth’s surface on a global scale. For future SAR systems, one of the key capabilities is to acquire images with both high-resolution and wide-swath. In parallel to the evolution of SAR sensors, more precise range models, and effective imaging algorithms are required. Due to the significant azimuth-variance of the echo signal in High-Resolution Wide-Swath(HRWS) SAR, two challenges have been faced in conventional imaging algorithms. The first challenge is constructing a precise range model of the whole scene and the second one is to develop an effective imaging algorithm since existing ones fail to process highresolution and wide azimuth swath SAR data effectively. In this paper, an Advanced High-order Nonlinear Chirp Scaling(A-HNLCS) algorithm for HRWS SAR is proposed. First, a novel Second-Order Equivalent Squint Range Model(SOESRM) is developed to describe the range history of the whole scene, by introducing a quadratic curve to fit the deviation of the azimuth FM rate. Second, a corresponding algorithm is derived, where the azimuth-variance of the echo signal is solved by azimuth equalizing processing and accurate focusing is achieved through a high-order nonlinear chirp scaling algorithm. As a result, the whole scene can be accurately focused through one single imaging processing. Simulations are provided to validate the proposed range model and imaging algorithm.
