基于分数阶傅里叶变换的星载SAR信号参数实时估计

针对星载合成孔径雷达（synthetic aperture radar, SAR）信号参数估计问题，提出了一种基于分数阶傅里叶变换的实时估计方法。首先，介绍了分数阶傅里叶变换的定义和chirp信号参数的估计原理。其次，在介绍星载SAR运行特点的基础上，针对单脉冲和脉冲串这两种情况进行了相应参数的实时估计：通过对接收到的星载SAR单脉冲信号进行分数阶傅里叶变换，可以估计出星载SAR的载频和调频率；通过对接收到的星载SAR信号的脉冲串进行分数阶傅里叶变换，可以估计出方位调频率。仿真和实验证明这种方法是可行的。

Real time estimation of space-borne SAR signal parameter using FrFT

A new method based on fractional Fourier transform (FrFT) is put forward to solve the problem of real-time parameter estimation of space-borne synthetic aperture radar (SAR) signals. The concept of FrFT and its estimation theory of chirp signals are introduced firstly. Then, after analyzing the feature of SAR flight, real-time parameters estimation are carried out respectively to cases of single pulse and pulse trains. FrFT is firstly applied to single pulse in the received signals, which can estimate the carrier frequency and rate of SAR signal. Then, FrFT is applied to pulse trains, which can estimate the azimuth rate of SAR signals. Theoretical analysis and numerical simulations show high accuracy of this method.