Micro-doppler Effect Analysis And Parameter Extraction

The micro-Doppler exists widely in the nature, which is induced by the micro-motion dynamics. The returned signal that incorporates vibrating and rotating, such as rotors of a helicopter, or the engine compressor, contain micro-Doppler signatures related to these structures. The micro-Doppler can be used to determine the dynamic properties of the micro-motion target, and offers a new approach for the analysis of target features.The main problems are studied as below:1. The basic model of micro-Doppler effect (including vibration, rotation, tumbling and coning motions), and the model of ballistic missile (including the warhead's spin, precession and nutation) are performed. The micro-Doppler theoretical formulas are derived, which are verified by the simulated results.2. The micro-Doppler signatures are analyzed by the time-frequency transforms (including short-time Fouriter transform and Wigner-ville transform). The impact of the angular frequency, carrier frequency and the amplitude are also analyzed.3. Based on the concept of the micro-Doppler effect, the method which separates the radar echo using the empirical mode decomposition is analyzed; the method which estimate the micro-Doppler frequency at any time we need and extract the micro-motion period using the spectrogram peak measurement is also analyzed.4. A new transform which can extract the micro-motion amplitude and phase simultaneously is introduced and the mathematical formula of this transformthe is also presented. We validate the performance of the transform by simulation, and the results show that the approach has good resolution in both frequency and phase, even in low SNR, i.e., -10dB, it can also be used to differentiate the targets. The empirical mode decomposition, the spectrogram peak measurement and new transform are combined to extract three parameters.5. Based on the parameter extraction method, a phase compensation method is introduced. By using the extraction parameters, a phase compensation function can be derived, and the range-crossrang results can be got clearly.An algorithm called range-Doppler interferometry is introduced. By using it, the image of rotating target can be got easily and clearly.By introduced the micro-Doppler, this paper mainly analyzed the parameter extraction method, which can extract the angular frequency, amplitude and phase of the micro-motion target. And image problems of the micro-motion target are also discussed. This paper provides the basis for extracting the micro-motion parameter more effectively, and getting three-dimensional image.