水下声信号激光相干探测的仿真与实验

建立波长1 550 nm的全光纤激光相干探测系统,系统采用全光纤设计,光路简单且稳定性高.数值仿真与实验结果表明,采用激光相干探测和时-频分析,可有效地提取水下不同频率、不同强度和不同深度的振动特征.该系统可实时探测出40~10 000 Hz的水下声信号,且测量标准偏差小于几个赫兹.因此,激光相干雷达用于水下目标的探测与识别具有实时性,该技术可为水下目标的特征提取和识别提供新的途径.

Coherent detection and simulation of the vibration characteristics of underwater acoustic signal

A laser coherent detection system with wavelength of 1 550 nm was established. The stability of the system has been improved because of the all-fiber optical path. The underwater vibration signals with different frequency, intensity and depth have been studied in experiments. The results show that the fluctuations of water surface are detected by the laser coherent detection system. The vibration characteristics of the underwater acoustic field can be extracted effectively by the time-frequency analyses. Experimental results indicate that the detection system can be used to detect real-time underwater acoustic signals at frequency from 40 Hz to 10000 Hz with test error less than a few Hz. Therefore the laser coherent radar can be used for feature extraction and recognition of underwater target in real time.