Research On Parameter Extraction And Recognition Of Target With Micro-motion

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.