Micro-Doppler Extraction And Parameter Estimation Of The Space Cone-shaped Target

The micro-motion refers to the micro motions such as mechanical vibrations, rotations, and accelerated movements of a target or any structure on the target except for its bulk translation. They might induce additional frequency modulations on the returned radar signal which generate sidebands about the target’s Doppler frequency, called the micro-Doppler effect. The micro-Doppler features can reflect the electromagnetic scattering characteristics, geometric structure and motion characteristics of the target, so they are considered as important signatures for the classification and recognition of ballistic missiles in recent years.This dissertation mainly focuses on the micro-Doppler extraction and the parameter estimation of the space cone-shaped target. The theories and techniques for the topic are studied from the three aspects, including the micro-Doppler modulations induced by micro-motions, the micro-Doppler extraction from the returned signal, and the estimation of motion parameters and structure parameters of the target with precession. The dissertation can be summarized as the following three points:1. We make an analysis on the scattering properties and the occlusion effect of the cone-shaped target, then establish the effective scattering point model. Taking the linear frequency modulation(LFM) signal as an example, we analyze the micro-Doppler modulations induced by precession and nutation on the returned signal, and then derive the micro-Doppler formulas for the two kinds of micro-motion dynamics in detail. The simulation results demonstrate the correctness of the theoretical analysis.2. In view of the space cone-shaped target, an approach to extract the micro-Doppler frequencies of the target with micro-motions based on the parameter estimation of the LFM signal combined with the random sample consensus(RANSAC) is proposed. In this method, firstly, the target echo signal is divided into several segments, and then each segment of the echo signal approximates to the sum of several components of the LFM signal, and an algorithm based on the extended Relax method is used to estimate the instantaneous frequency and the rate of the each LFM signal. Thus the micro-Doppler curve of each effective scattering point is estimated by the RANSACalgorithm. In the simulation experiments, the performance of the proposed method is evaluated via the simulation data and electromagnetic computation simulation data.3. The dissertation introduces a method to estimate motion parameters and structure parameters of the space cone-shaped target with precession. We analyze the properties of the instantaneous micro-Doppler frequency variations of the top and bottom scattering points under different radar aspect angles. We can firstly estimate the radar aspect angles through solving the simultaneous equations based on the properties of the variations, and then we can estimate the target’s motion parameters and structure parameters, such as height, bottom radius, distance from the rotation center to the bottom and precession angle. Experiments based on the simulation data verify the validness of the method.