Feature Extraction Of Micro-Doppler Based On SAR For Ground Targets

Synthetic aperture radar has become the radar of an important direction in the field and it's position can not be replaced in practice, whose imaging with high precision, all-weather imaging, adaptability and other characteristics as a high-resolution imaging radar. However, with the development of radar imaging technology and the anti-Target Recognition, airplanes, satellites and other different carriers have more performance requirements of synthetic aperture radar. How to effectively overcome the micro-motion targets for synthetic aperture radar imaging system accuracy is the main technical difficulty at present.Micro-motion is of the targets which detected by radar, existing as a series of vibration and turning as well as high level motion of other forms but except the translation of bar centric. Micro-Doppler effect is that the radar echo of motion targets possess had doppler effect, and the micro-motion of targets can also create Doppler modulating action to radar echo likewise. The mainly affect of Micro-Doppler effect is that the micro-motion targets can make synthetic aperture radar imaging blurred, so this article aimed to study how to extract the micro-motion characteristics of micro-motion targets of Synthetic aperture radar system, and then use the extracted micro-motion characteristics of synthetic aperture radar images to compensate.In order to overcome the phenomenon of fuzzy image caused by micro-motion targets of synthetic aperture radar, extraction of the micro-motion characteristics of micro-motion targets and the problem of imaging compensation of synthetic aperture radar were spreader out in this article. First of all, Micro-Doppler effect of synthetic aperture radar had been built the model in this study, and detailed derivation of mathematics also had been carried out, which laid the theoretical foundation of extracting the micro-motion characteristics of micro-motion targets. The second, micro-Doppler effect model of conventional radar and synthetic aperture radar were established based on the two typical micro-motion forms of vibration and writhing. The third, influence of targets micro-motion parameters and radar parameters on micro-synthetic aperture radar effect were analyzed and the key parameters of extracting feature extraction of micro-motion targets was also pointed out.Time-frequency analysis is the key technology in feature extraction of micro-motion targets. In this paper, the merit and demerit of various kinds time-frequency analysis was been aggregated based on wigner-ville distribution and short time Fourier transformation to carry out. S time-frequency analysis applied to synthetic aperture radar system successfully, and the simulation experiments showed that S time-frequency analysis had high time-frequency concentration. In order to make the feature extraction and imaging compensation of synthetic aperture radar micro-Doppler come true, S time-frequency analysis and empirical mode decomposition method were combined to extract the micro-motion characteristics of single micro-motion targets and multi-micro-motion targets in the research, according to which the imaging of Micro-synthetic aperture radar targets was compensated, and its correctness was proved through Simulation experiment.Finally, a summary of the full-stext, which pointed out the direction of next research as well as the development of Micro-Doppler effects.