水下目标弹性声散射信号分离

Separation of elasto acoustic scattering of underwater target

水下目标弹性声散射与其他声散射成分在时域和频域上均存在混叠,现有信号处理方法受分辨力限制无法在混叠状态下识别目标弹性声散射特征.针对这个问题,提出了一种目标弹性声散射信号分离方法.以目标回波亮点模型为基础,分析了线性调频信号入射时目标声散射成分的信号特性,提出了一种目标声散射成分向单频信号的映射方法,并理论推导出了目标声散射结构与映射结果之间的线性对应关系,实现了通过窄带滤波分离出目标弹性声散射成分.仿真与消声水池实验数据处理结果表明,该方法基本可以完全分离出目标回波信号中的弹性声散射成分,分离出的弹性声散射具有与理论一致的信号特征,验证了该分离方法的有效性.

An elastic acoustic scattering by underwater target could be mixed with other acoustic scattering components in both time and frequency domains, and the existing signal processing methods could not discriminate the elastic feature of target in the mixed status. For solving this problem, a signal separation method for elastic acoustic scattering is proposed. Based on the highlight model of target echo, the characters of the target acoustic scattering signal when the linear frequency modulation signal is transmitted, are analyzed, and a method for mapping the acoustic scattering signal of the target to a single frequency signal is proposed. Theoretical derivation shows that there is a simple linear relationship between the acoustic scattering structure of the target and the mapped result, then the elastic acoustic scattering signal of the target can be separated by a narrow-band filtering. Simulation results show that the correlation coefficient between the separated target acoustic scattering and the orginal simulation signals are about 0.99, indicating that the acoustic scattering components in the simulation target echo can be wholly separated. Experimental data-processing results of the target acoustic scattering measurement in an anechoic pool show that the mid-frequency enhancement effect can be observed in the spectrum of the separated elastic acoustic scattering, and every target acoustic scattering component can be recognized on the time-frequency distribution of separately processed target echo. There is a bowl-shape interference fringe on the angle-spectrum of the separated target elastic acoustic scattering components which is consistent with the theoretical signal＇s feature of the elastic acoustic scattering, and the effectiveness of the separation method proposed is proven.