【作者】 王璐；

【导师】 刘宏伟；

【作者基本信息】 西安电子科技大学 ， 信号与信息处理， 2010， 硕士

【摘要】 利用雷达目标微动特性进行目标检测和识别近年来受到雷达界广泛的关注。一般把雷达目标除质心平动以外的小幅振动、转动和其它高阶运动统称为微动,微动引起的雷达可观测量微多普勒特征包含了目标的运动、尺寸、形状等大量信息。因此,微动特征和微多普勒特征作为有效的雷达识别特征,为目标识别提供方法和思路。本文研究了微动目标的运动参数估计方法和微动目标的雷达特征提取技术,论文首先对国内外微动目标雷达特征分析与提取的研究现状、论文的研究背景、本文主要工作进行了详细的阐述。论文首先介绍了微动以及微多普勒的概念,分析了微动对目标回波的调制作用和微多普勒的数学原理。在散射中心模型下,建立了弹头微动的运动模型,推导了进动状态下,进动目标回波和微多普勒的数学表达式,研究了单个散射点下微动特征的提取和微动目标运动参数估计的方法。论文从时频分析技术方面研究了微动目标的雷达特征提取和参数估计的方法。研究了导弹目标进动状态下其短时傅里叶变换的数学表达式,提出了估计多散射点的瞬时多普勒线性和的方法,对估计的各散射点微多普勒线性和做傅里叶谱分析,可估计弹头进动时的各个运动参数。并提出傅里叶谱的波形熵特征,有效地区分进动弹头和自旋诱饵。论文研究了微动目标的傅里叶谱,从理论上推导了弹头在微动状态下的傅里叶谱的数学表达式,得到了进动状态下傅里叶谱谱峰出现的位置,从而得到不同微动状态下的傅里叶谱特征,提供一种用于区分复杂运动如进动和简单运动如自旋或摆动的方法。并研究了利用傅里叶谱和倒谱估计微动目标运动参数的方法。论文还研究了从进动目标的回波中,直接提取进动目标的运动参数的方法。最后,对论文工作和研究方向进行了总结,指出了需要进一步研究和解决的问题。更多还原

【Abstract】 Using target micro-motion characteristics for target detection and recognition is a hot topic in radar community recently. Micro-motion is commonly referred to small mechanical vibrations or rotations in addition to mass translation which may induce additional frequency modulation on the received target echoed signal, called micro-Doppler effect. Micro-Doppler signatures enable some properties of the target to be determined such as motion condition, size, shape, et al. Therefore, using micro-motion signature and micro-Doppler signature as radar features to identify targets of interest is proven to be an effective way.This paper investigates methods for motion parameter estimation from and radar signature extraction from targets with micro-motions. Brief reviews and comments of the research background, present situation, and the main contributions of this paper are introduced at the very beginning.Firstly, this paper introduces the basic conceptions of micro-motion and micro-Doppler, examines the modulation to the target echoes induced by micro-motion as well as mathematics and computation technique involved in micro-motion or micro-Doppler. This paper establishes a motion model for warhead with micro-motion, derives the mathematic expression for returned echo and the micro-Doppler of the target of interest, and studies the method for motion parameter estimation and signature extraction.Time-frequency transform is used to analyze micro-Doppler signal due to its time-varying property for target feature extraction. The short-time Fourier Transform (STFT) mathematic expression for echoes from target with micro-motion is derived. Based on this expression a method for estimating the linear sum of micro-Doppler for multi-scatters is proposed. Then parameter extraction can be done by applying the Fourier Transform to the linear sum. Then waveform entropy can be used as an effective characteristic to recognize the warhead from decoys.This paper also investigates the Fourier spectrum of the target with different micro-motion. The positions where the spectrum peaks locate are estimated in a mathematic way. Then features are extracted for identifying warhead from decoys based on their difference in micro-motion. This paper also investigates the application of Fourier spectrum and cepstrum in the parameter estimation for target with micro-motion.In addition to the spectrum application, the paper also makes efforts on methods for parameter estimation from other aspects.This paper is concluded with a summary and a list of some significant and valuable problems as a reference in further research.更多还原