摘要
逆合成孔径雷达 (ISAR)机动目标成像受到了研究者的广泛重视。在已有的机动目标成像算法中 ,通常假设在综合孔径处理期间 ,各距离单元内各散射回波是等幅线性调频信号。在实际中 ,以上假设仅是近似成立 ,基于此假设的机动成像算法难以得到较高质量的目标图像。本文采用更精确的信号模型——多分量调幅—线性调频(AM— L FM)信号表示实际机动目标的各距离单元回波 ,并提出一种 AM— L FM信号参数估计方法以及快速算法 ,通过估计信号的时变振幅、调频率和初相等参数 ,得到了更高质量的机动目标的动态 ISAR像序列 ,以利于目标识别 ,而且运算量比已有算法要小。
Most of dynamic inverse synthetic aperture radar (ISAR) imaging methods for maneuvering targets are based on time frequency distribution, and suppose scatterers′ echoes have constant amplitude and linear frequency modulation. In fact, when the target has dihedrals and trihedrals component, or scatterers exist Migration Through Resolution Cells(MTRC), scatterers move in or out the analyzing range cell, these situation all will cause that the amplitude is not a constant, and for a maneuvering target, the Doppler of scatterer echo after translational motion compensation is time varying, usually, its time frequency distribution can be approximated a line, if not a line, it can be approximated a part line. In this paper, we propose a multicomponent amplitude modulation and linear frequency modulation (AM LFM) signal parameter estimation method and a fast algorithm. The algorithm first finds the frequency modulation rate of one component by dechirping and searching, second, demodulates this component to an amplitude modulation sinusoidal signal, third, separates and cleans this component in Fourier domain, and estimates instantaneous amplitude, then estimates for next component, finally we get all scatterer′s instantaneous amplitude and frequency, and dynamic ISAR images are obtained now. The images obtained from real data are better than that obtained by other methods, which helps automatic target recognition (ATR), moreover the computation load is small.
出处
《现代雷达》
CSCD
北大核心
2000年第6期44-49,共6页
Modern Radar
基金
国家自然科学基金!( No:6983 10 40 )资助课题
电科院国防科技预研基金!( No:7.4.2 .1)资助课题
