使用分数阶傅里叶变换(FrFT)进行SAR动目标测速的传统计算方式是二维搜索，即遍历所有的旋转角度进行FrFT计算，在二维平面内搜索峰值获得最优解。该方法需要在计算精度和计算量之间权衡。提出一种基于时频平面几何信息的动目标测速和定位方法，首先计算两个不同角度下的FrFT及其投影长度；然后利用时频平面内的几何关系，计算动目标的最优旋转角；最后计算最优旋转角下的FrFT，并对动目标测速和定位。值得注意的是，通过选择关于π对称的两个旋转角度，可以进一步抑制杂波。综上，该方法具有速度快、参数估计精度高的优点。通过仿真实验和真实数据实验，验证了提出方法的有效性和优越性。
In traditional, the way to measure the velocity of moving targets using FrFT(fractional Fourier transform) is based on 2D searching. The FrFT is calculated by traversing all angles and the optimal solution is the peak value of 2D plane. The method needs to trade off computational accuracy and computational complexity. In this paper, a new method of velocity measurement and location for moving targets is proposed. Firstly, the FrFT of two different angles and their projection are calculated. Then, the optimal rotation angle for moving target is calculated by using geometric relationship in the time-frequency plane. Finally, the FrFT under the optimal rotation angle is calculated, and velocity and position parameters of moving target are calculated. Moreover, static cluster can be suppressed if two angles for FrFT are symmetric about π. In general, the proposed method is faster and more accurate than the traditional method. The effectiveness and superiority of the method are verified by simulation and real data experiments.
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