Research On Parameters Estimation For Radar Targets With Micro-motions

Micro-motion features which contain the unique structural information and motion information can be used as important features in target recognition. In this work, we do intensive research works on the modulation effects of radar echo induced by translation and micro-motion as well as micro-motion parameter-estimation issue in the presence of translation. According to the interaction of translation and micro-motion, three methods are developed to estimate micro-motion parameters. These methods are capable of estimating micro-motion parameters of radar targets in the presence of translation.The background and significance of this research as well as the related work are introduced in Chapter 1. The state of the art is summarized under four aspects: the radar echo modeling of targets with micro-motion, components separating of radar echo, micro-motion feature extraction, and translation compensation. The contributions and structure of this work are presented at the end of this chapter.In Chapter 2, the modulation effect of radar echo induced by translation and micro-motion are studied. The wide-band and narrow-band radar echo models of targets are established based on the motion model of space targets with precession, the point-scatterer model and RCS variation of the target. Based on this, the power modulation characteristic, micro-Doppler modulation characteristic, micro-Range modulation characteristic induced by micro-motion dynamics, Doppler modulation characteristic induced by translation dynamics and the interaction of translation and micro-motion are presented.In Chapter 3, micro-motion parameters estimation of targets from narrow-band and wide-band radar signal in the presence of translation is well studied. As for narrow-band signal, the periodicity of time-frequency distribution(TFD) of micro-Doppler signal is presented; we show that the periodicity of TFD is replaced by circular periodicity in the presence of translation. In view of this, the circular correlation coefficients of TFD are employed to characterize the circular periodicity of TFD and to provide an estimate of the micro-motion period. As for wide-band signal, we study the extraction of micro-Range of the scatterer and propose a high-order difference sequence-based approach for estimating the micro-motion period. The circular correlation coefficients–based and the high-order difference-based approaches achieve micro-motion parameter-estimation in the presence of translation.In Chapter 4, micro-motion parameter-estimation issue in the presence of complicated translation is studied. Inspired by the differential element method, segmented translation compensation(STC) is proposed to cope with complicated translations such as maneuvering. The STC can compensate the translation at the largest extent. A TFD calculation strategy based on extended data is introduced to suppress the end effect of TFD and to provide a more accurate estimation of instantaneous frequency. Inspired by the shift invariant difference operation, time-frequency squared difference sequences(TFSDS) is employed to estimate the micro-motion frequency. The TFSDS can remove the effect of residual translation and avoid components separation of radar echo. The combination of STC and TFSDS enables us to extract micro-motion features in the presence of translation.The research work and contribution of this dissertation is concluded in the last chapter, and next steps of the study as well as the potential problems and difficulties are presented.