直升机声源激发浅海水下声场特性与定位问题研究

The issue of air-to-water sound field and water-to-air localization has been paid much attention recently, since there is a strong demand from practical applications. Owing to the great difference of acoustic characteristic impedance between air and water, only a little energy generated by an airborne source could transmit into water. Therefore, the SNR (Signal to Noise Ratio) of the sound signals received by the underwater sensors is very low, which makes it very difficult to do further research on the air-to-water sound propagation. Compared with the theoretical research, the experimental research is relatively scarce on the air-to-water sound propagation.This item will carry on research with this problem both theoretically and experimentally.An experiment will be conducted with high level sources such as a helicopter.The signal of the airborne source will be received by an underwater HLA (horizontal line array). The water-to-air localization technique will be researched furthermore based on the experimential data.

空气中声源激发的水下声场及其水下探测是当前国家有迫切需求的研究方向。由于空水声学介质特性阻抗存在巨大差异，使得水下接收信号很弱，相关海上实验难以在较远距离上取得有效数据，有报道的实验研究不多。申请者拟对空气声源激发较远距离水下声场特性和水下探测问题开展研究，利用现有理论模型对较远距离水下声场传播和相关特性进行分析和研究，开展海上实验，利用直升机作为噪声源，使用大尺度高灵敏度水平阵在水下进行接收。此外，还将利用实验数据研究空气声源目标的水下探测和定位方法研究。

空气声源激发水下声场问题近年来日益引发众多关注。由于空气、海水介质声阻抗差异巨大， 空中声源辐射的噪声透射入水的能量损失很大， 加之水中声源目标的干扰，从水下探测空中声源相对困难。本项目开展了空气声源激发水下声场特性研究以及水下对空气中声源目标的探测定位研究。在浅海开展了水下水平阵探测空气中直升机声源目标实验，最远实验距离16.8km；针对空中声源普遍存在线谱的特点， 首先利用线谱识别、提取与跟踪以及线谱加密技术对水下水平阵接收信号进行线谱分析，再通过剔除强干扰目标的线谱， 成功分离出包含空中声源的线谱信号，实现了直升机声源水下声场传播损失估算最远距离达16.8km并实现目标探测。通过理论和实验数据分析， 验证了探测结果的正确性。结果表明，线谱检测方法可有效抑制同频干扰，在低信噪比、多干扰环境下成功实现了水下对空运动声源的线谱探测。在深海利用深海垂直阵和扬声器声源开展了空气中声源激发水下直达区声场特性试验，最远有效实验距离14.5km，对实验结果分析显示，同一距离上不同深度水听器接收信号的信噪比有着明显差距，对4.5-14.5km范围内垂直阵元接收数据的分析显示，接收点深度越深，水下接收信号的效果越好，利用实验数据对3472米深处阵元在4.5-14.5km的声传播损失进行了计算，计算结果与理论结果进行比较，二者结果符合很好。本项目研究成果对于水下声阵对空预警探测具有重要意义。