Angle-micro-Doppler frequency image of underwater target multi-highlight combining with sparse reconstruction
Siwei Kou, Xi’an Feng
Abstract
Aiming at the problem of low angle resolution and difficult extraction of time-varying features in underwater target multi-highlight acoustic imaging, an acoustic imaging method of multi-highlight angle-micro-Doppler frequency for underwater target combining with sparse reconstruction is proposed by introducing sparse decomposition and time–frequency analysis into array signal processing. According to the difference between the underwater target highlight reflected wave modulation form caused by the micro-Doppler effect and time–frequency distribution, a kind of MicroDopplerlet time–frequency atom matching the complex modulation of the highlight reflection wave is designed. The multi-component signal processing is transformed into multiple single component signal processing problems by separating the highlight reflected wave from the echo by MP decomposition. In addition, a two-dimensional subspace processing method based on MP (MP-MUSIC) and a time–frequency distribution based on MP (MP-WVD) are constructed for sparsely reconstructed reflected wave of one single highlight, which are used to extract azimuth angle, pitch angle, micro-Doppler frequency information and acoustic image respectively. The proposed method has the advantages of noise robustness, high resolution and the ability to solve the underdetermined problem. The simulation results show that the proposed method can distinguish the multi-highlight structure of underwater target, and estimate the highlight angle, micro-Doppler frequency and micro-motion parameters of the target components correctly.