Research Of Radar Target Parameter Estimation Technology Based On Copula Theory

The micro-Doppler phenomenon is generated by micro-motions. For a moving radar target, the target itself or the structures of the target are often accompanied with micro-motions. Micro-motions of the target induce a Doppler frequency modulation of the radar echo signal, and its micro-Doppler frequency contains the unique information of motion characteristics of the target. The extraction of the motion information can help to target detection and target recognition. As the research of the micro radar target is being more and more deeply, and its research value is being more and more valuable. So far, radar signal detection, parameter estimation and feature extraction technology of radar micro-motion target has become a hot topic in radar field.In this thesis, micro-motion target is the research object, and a method combining the theoretical derivation and simulation is been used. And the micro-Doppler is been analyzed and three conventional parameter estimation methods are been studied deeply. In order to improve the accuracy of parameter estimation, a method based on Copula theory is been proposed. The main contents of this thesis are as follows:First of all, The concept of micro-Doppler phenomenon and the general definition of micro motion is introduced, and mathematical models of four typical micro motion type(motor, vibration, rotation, rolling) are given, and their respective micro-Doppler frequency calculation formula are derived, and the correctness of the mathematical derivation is verified by numerical simulation. The commonly used time-frequency analysis methods are given, and their advantages and disadvantages are compared and summarized. And then, the spectrums of micro-Doppler under X band and THz band are compared, and the simulation results show how frequency effect to micro-Doppler frequency.Then, on this basis, the W-V peak detection method, the first-order time conditional moment method, Hough transform method are used to deal with micro-target radar echo signal processing. And then, their motion parameters, such as velocity, acceleration, vibration frequency, vibration amplitude, are been estimated. And the estimate performances of these methods in case of noise, noise, single scattering points, multiple scattering points are been analyzed, as well as the mean square error(MSE) of parameter estimation along with the change of signal to noise ratio(SNR) are been analyzed.Finally, The Copula theory is introduced, and by designing simulation experiments, an important property that the Copula can fit the joint probability distribution is verified to be correct. And then, a method of parameters estimation based on Copula theory is been put forward, which estimate parameters by conventional methods on the basis of spectral optimized by copula function. And its effectiveness is verified by simulation, which proves the Copula-based parameter estimation method not only can improve the performance of parameter estimation without slowing down the speed of estimation, and meanwhile it has good anti-noise performance.