CAJ | 학술논문

某些分时采样干涉式微波辐射计成像系统,通常采用稀疏阵列,如圆环稀疏阵列.由于天线阵列优化设计时天线排布位置受限以及天线物理尺寸等限制,具有非均匀空间频域采样的特点.传统的图像重构方法是将非均匀空间频域点插值到均匀的笛卡尔坐标下,补偿空间频率密度,再进行逆快速傅里叶变换.这些插值方法不可避免地会引入误差或者混叠,并且是以假设空间频域的光滑性为前提的,具有局限性.与传统的插值方法不同的是,该文采用最小最大优化准则,先假设图像,再进行共轭梯度迭代快速非均匀傅里叶变换匹配的算法,绕开了空间频域光滑的假设.模拟实验结果表明此算法能够更加快速精确地重建图像.
모사분시채양간섭식미파복사계성상계통,통상채용희소진렬,여원배희소진렬.유우천선진렬우화설계시천선배포위치수한이급천선물리척촌등한제,구유비균균공간빈역채양적특점.전통적도상중구방법시장비균균공간빈역점삽치도균균적적잡이좌표하,보상공간빈솔밀도,재진행역쾌속부리협변환.저사삽치방법불가피면지회인입오차혹자혼첩,병차시이가설공간빈역적광활성위전제적,구유국한성.여전통적삽치방법불동적시,해문채용최소최대우화준칙,선가설도상,재진행공액제도질대쾌속비균균부리협변환필배적산법,요개료공간빈역광활적가설.모의실험결과표명차산법능구경가쾌속정학지중건도상.
@@@@Some thinned array, such as circle thinned array, is used by synthetic aperture interferometric radiometer to realize time-shared sampling. The thinned array may take non-uniform sampling of spatial frequencies due to antenna array structure optimization, the limitation of affined area and the physical size of antenna elements as well. In some traditional image reconstruction methods, non-uniform spatial frequency samplings are usually inserted to uniform Cartesian coordinate. And the spatial frequency densities are compensated. However, as the spatial sampling intensity is assumed to be quite smooth, these methods still bring errors and blurring in spite of different interpolation functions. Moreover, iterative methods that adopted straight Fourier transform are time consuming as they applied to non-uniform spatial frequency samplings. In this paper, another fast interactive image reconstruction method is introduced. The kernel of this algorithm is min-max formulation. The specific procedure of this method is as follows: (1)initiating the image; (2)taking non-uniform fast Fourier transform;(3)operating iterative conjugate gradient matched algorithm. The numerical simulating experiments show that, as spatial frequency samplings density is not smooth, the image can be still reestablished fast and accurately.