Synthetic aperture radar (SAR) was originally exploited to image stationary scenes. However, it is important to derive target information of velocity for many applications. The fractional Fourier transform (FrFT) is a generalization of the classical Fourier transform and is well-known as a useful tool to estimate the chirp rate of linear frequency-modulated (LFM) signals. Motion compensation is critical to moving target imaging. It is difficult for us to obtain the actual motion parameters in real scenarios. Based on the moving target echo model in airborne along-track interferometric SAR (ATI-SAR) and expression of the ATI phase, a method is proposed to estimate the ship velocity by combining the ATI phase with FrFT. First, we use the FrFT to evaluate the chirp rate of the moving target echo. Then, we construct an equation to estimate the ship velocity using the chirp rate estimation, peak response time, and ATI phase. Finally, the simulation experiments are used to validate the effectiveness of the proposed method.

中文翻译：

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基于分数阶傅里叶变换的机载航迹干涉SAR图像中船速估计

合成孔径雷达（SAR）最初用于对静止场景进行成像。但是，对于许多应用而言，获得速度目标信息很重要。分数阶傅立叶变换（FrFT）是经典傅立叶变换的概括，众所周知是有用的工具，可用来估计线性调频（LFM）信号的线性调频率。运动补偿对于移动目标成像至关重要。在实际场景中，我们很难获得实际的运动参数。基于机载沿航迹干涉SAR（ATI-SAR）中的运动目标回波模型，并通过ATI相的表示，提出了一种将ATI相与FrFT相结合的舰船速度估计方法。首先，我们使用FrFT来评估运动目标回波的线性调频率。然后，我们构造了一个方程，使用the率估计，峰值响应时间和ATI相位来估计船速。最后，通过仿真实验验证了所提方法的有效性。