Research On Features Extraction And Reconstruction Of Micro Doppler Of Ballistic Targets

The signal modulation caused by micro motions including vibration, rotating, rolling and precession between the radar and targets results in the so called micro-Doppler effects. Extraction and measurement of the micro-Doppler parameters as well as the constructions of the targets are able to reveal the motion information, therefore, the targets detection and identification technique based on the micro-Doppler parameter estimation is one of the most potential methods in the target precise detection field. The achievements of the micro-Doppler characteristic extraction of the ballistic targets are introduced as following:1. An analysis of the doppler modulation by the target with micro-motions is carried out in the situations of both narrow-band and wide-band signals. Radar signal models of the target precession are established, and the modulation characteristics of micro-Doppler are studied. Then, the quantitative expressions are induced. In the end, a research on extraction tools is given based on the time-frequency algorithms, which is theoretically meaningful for the extraction, rebuilding and estimation of the micro-motion characteristics.2. The short time iterative adaptive approach-inverse radon transform(STIAA-IRT) algorithm is proposed in the narrow-band situation. Firstly, aiming at dealing with the precision problem of poor frequency resolution resulting in the difficulty to distinguish the multi-component signals overlapping seriously and neighboring when we use the conventional time-frequency techniques, a method called STIAA is proposed. Then, the IRT is employed to extract the features of the multi-component signals, which makes it possible to acquire the complete micro-Doppler information of targets with low Signal to Noise Ratio. The simulation results demonstrate the effectiveness of the proposed method has an advantage over the short time fourier transform and S method.3. In the wide-band situation, a parameter focusing and mixing estimation algorithm is proposed based on the IRT. Firstly, in order to deal with the migration problem of the moving target, a wide-band signal is divided into several narrow-band signals, and the micro-Doppler time-frequency spectrum of each band is derived with the STIAA algorithm. Then, we propose a parameter space transform after the IRT, which would realize the combination of different sub-bands. This algorithm would derive the complete micro-Doppler signals in the wide-band case and promote the accuracy of the estimated parameters. Simulation results are also provided to validate the effectiveness of the proposed method.