基于改进型快速双线性参数估计的复杂运动目标ISAR成像

ISAR Imaging of Targets with Complex Motion Based on the Modified Fast Bilinear Parameter Estimation

针对复杂运动目标的逆合成孔径雷达(ISAR)成像中多普勒扩散导致的成像质量下降,该文在建立方位回波信号为立方相位信号(CPS)的基础上,提出一种基于改进型快速双线性参数估计的复杂运动目标ISAR成像方法。该方法通过利用双线性立方相位函数,非均匀快速傅里叶变换(NUFFT),基于Chirp-z的尺度变换以及快速傅里叶变换(FFT)等操作,能够快速实现CPS参数估计和复杂运动目标的ISAR成像。由于实现过程均采用NUFFT和FFT快速实现,该方法计算量小,并且双线性操作可以保证其具有较好的抗噪声性能和交叉项抑制性能。理论分析和仿真结果验证了该ISAR成像算法的有效性。

In view of image defocus caused by Doppler frequency shift in ISAR imaging of targets with complex motion, this paper characterizes the azimuth echoes as Cubic Phase Signal （CPS） and proposes an ISAR imaging algorithm for targets with complex motion based on the modified fast bilinear parameter estimation. This algorithm can achieve parameter estimation of CPS and ISAR imaging quickly by employing the cubic phase bilinear function, NonUniform Fast Fourier Transform （NUFFT）, scale transform based on Chirp-z transform and Fast Fourier Transform （FFT）. The computational cost is low due to the NUFFT and FFT in implementation procedure, and bilinearity guarantees a high anti-noise performance and a good suppression on cross-terms. The theoretical analysis and simulation results demonstrate the effectiveness of the proposed ISAR imaging algorithm.