Laser-Induced Acoustic Air-Water Trans-Medium Communication Based on PWM
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摘要: 激光致声通信作为实现空-水跨介质无节点通信的关键技术, 其研究和应用日益受到关注。在高重复频率条件下, 传统的基于单脉冲识别的调制解调方式由于脉冲间相互干扰加剧, 对码元判定造成明显干扰进而导致误码率较高而无法正常通信。针对此, 文中提出了一种采用基于脉宽调制(PWM)的新型激光致声通信方法, 采用最大重复频率为500 Hz的Nd: YAG脉冲激光器, 通过调整激光脉冲数量产生不同宽度的PWM调制信号, 然后在接收端通过脉冲宽度进行码元识别。实验结果表明, 采用PWM调制的通信方式可以有效降低脉冲之间干扰带来的译码错误, 在最高400 Hz重复频率下误码率仅为8%, 提升了高重复频率下激光致声通信的可靠性和有效性。Abstract: Laser-induced acoustic communication has emerged as a critical technology for facilitating air-water trans-medium nodeless communication, garnering increasing attention in research and application. At higher repetition frequencies, traditional modulation and demodulation techniques based on single-pulse recognition face challenges due to exacerbated interference among pulses, significantly disrupting code element determination and leading to high error rates that impede effective communication. To address this issue, a novel laser-induced acoustic communication method employing pulse width modulation (PWM) was proposed. Experiments utilized an Nd:YAG pulsed laser with a maximum repetition frequency of 500 Hz, and the number of laser pulses was adjusted to generate PWM signals of varying widths, with code element recognition achieved at the receiving end based on pulse width. The experiment results show that the PWM-based communication method effectively minimizes decoding errors due to inter-pulse interference, achieving commendable performance at the highest repetition frequency of 400 Hz with an error rate of just 8%. This improvement significantly enhances the reliability and effectiveness of laser-induced acoustic communication at high repetition frequencies.
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Key words:
- trans-medium communication /
- laser-induced acoustics /
- nodeless /
- PWM modulation
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图 1 基于激光致声的空-水跨介质通信
Figure 1. Laser-induced acoustic air-water trans-medium communication
图 2 DFB-FL水听器结构组成
注: PGC为相位产生载波(phase generated carrier); PZT为压电陶瓷(piezoelectric ceramics)
Figure 2. Structure composition of DFB-FL hydrophone
图 4 激光致声通信实验系统结构示意图
Figure 4. Schematic diagram of laser-induced acoustic communication experimental system
图 5 接收端信号检测处理流程图
Figure 5. Flow chart of signal detection and processing at the receiver end
图 6 滑动窗口激光致声信号检测算法流程
注: MFCC为梅尔频率倒谱系数(Mel frequency cepstrum coeffi- cient)
Figure 6. Flow chart of detection algorithm of sliding window laser-induced acoustic signal
图 7 不同重复频率的激光声信号
Figure 7. Laser acoustic signals with different repetition frequencies
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