构建了激光声实验测量系统,利用脉冲激光聚焦击穿水介质产生声信号,由水听器将声信号转换成电信号并送入数字存储示波器。分析了激光声信号的时频域数学模型,通过实验对单个激光声信号的时频域特征进行了研究,对激光声通信的信号调制方式进行了理论分析和实验验证。研究结果表明:激光声信号的脉宽约为20μs,其能量主要集中在200 k Hz内,这其中100~200 k Hz内的能量占到的比例大约有50%,通过对激光声信号进行幅度调制和频率调制,可以有效实现激光声通信过程。
Experimental system for laser-induced acoustic signals was built. Acoustic signal was induced by pulsed laser focusing into water. A hydrophone was used to convert acoustic signals into electric signals. The mathematic model for laser-induced acoustic signals in time domain was analyzed. Energy distribution of laser-induced acoustic signals in frequency domain was studied. The modulation method for communication based on laser-induced acoustic signal was theoretically studied and proved by experiments. The results are as follows: Pulse width of laser-induced acoustic signal is about 20 μs. The laser-induced acoustic signals have most of their energy concentrated within 200 k Hz, where half of that is between 100 k Hz and 200 k Hz. Magnitude modulation and frequency modulation are effective methods in communication based on laser-induced acoustic signal.