Sun Lin, Chen Weidong
Key Laboratory of Electromagnetic Space Information of the Chinese Academy of Sciences, University of Science and Technology of China, Hefei 230027, China.
Sensors (Basel). 2018 Mar 23;18(4):951. doi: 10.3390/s18040951.
For micromotion scatterers with small rotating radii, the micro-Doppler (m-D) effect interferes with cross-range compression in inverse synthetic aperture radar (ISAR) imaging and leads to a blurred main body image. In this paper, a novel method is proposed to remove the m-D effect by promoting the joint sparsity in the time-frequency domain. Firstly, to obtain the time-frequency representations of the limited measurements, the short-time Fourier transform (STFT) was modelled by an underdetermined equation. Then, a new objective function was used to measure the joint sparsity of the STFT entries so that the joint sparse recovery problem could be formulated as a constrained minimization problem. Similar to the smoothed l 0 (SL0) algorithm, a steepest descend approach was used to minimize the new objective function, where the projection step was tailored to make it suitable for m-D effect removal. Finally, we utilized the recovered STFT entries to obtain the main body echoes, based on which cross-range compression could be realized without m-D interference. After all contaminated range cells were processed by the proposed method, a clear main body image could be achieved. Experiments using both the point-scattering model and electromagnetic (EM) computation validated the performance of the proposed method.
对于具有小旋转半径的微动散射体，微多普勒（m-D）效应会干扰逆合成孔径雷达（ISAR）成像中的横向距离压缩，并导致主体图像模糊。本文提出了一种通过在时频域中促进联合稀疏性来消除m-D效应的新方法。首先，为了获得有限测量的时频表示，将短时傅里叶变换（STFT）建模为一个欠定方程。然后，使用一个新的目标函数来衡量STFT项的联合稀疏性，以便将联合稀疏恢复问题表述为一个约束最小化问题。类似于平滑l0（SL0）算法，使用最速下降法来最小化新的目标函数，其中投影步骤经过调整以使其适合于消除m-D效应。最后，利用恢复的STFT项来获得主体回波，在此基础上可以实现无m-D干扰的横向距离压缩。在用所提出的方法处理所有受污染的距离单元后，可以获得清晰的主体图像。使用点散射模型和电磁（EM）计算的实验验证了所提方法的性能。
