基于多普勒域多通道的机载合成孔径雷达自聚焦算法

An Autofocus Algorithm Based on Doppler-domain Multichannel for Airborne SAR

在多通道自聚焦(MCA)和傅里叶域多通道自聚焦(FMCA)的基础上,该文提出一种基于多普勒域多通道的机载合成孔径雷达自聚焦算法。该算法同样是直接在线性代数的理论框架下推导得到,能够在不迭代的情况下进行相位误差的估计和补偿以实现SAR图像的聚焦。该算法不像MCA和FMCA那样在图像域估计相位误差,而是在距离压缩方位多普勒域(方位未压缩)里进行相位误差估计。同时该算法不需要SAR成像场景中含有低散射区的假设,从而使其能够应用于条带模式SAR。不同情况下条带SAR数据的处理结果验证了该算法的有效性和可行性。

On the basis of the Multi Channel Autofocus（MCA） algorithm and the Fourier-domain Multi Channel Autofocus（FMCA） algorithm, an autofocus algorithm for airborne SAR based on Doppler-domain multichannel is proposed. The proposed autofocus algorithm is also directly derived under a linear algebraic framework, allowing the phase error to be estimated and removed in a noniterative fashion to achieve the well-focused SAR image. However, unlike MCA or FMCA applied to the image domain, the proposed autofocus algorithm is used to estimate the phase error in the range compressed azimuth Doppler domain（azimuth uncompressed）. In addition, it does not require the assumption of a low-return region contained to the SAR image, which makes it applicable to the strip-map mode SAR. The processing results of strip-map SAR data in different cases demonstrate the validity and feasibility of the proposed autofocus algorithm.