【作者】 刘丹；

【导师】 衣文索；

【作者基本信息】 长春理工大学 ， 仪器仪表工程（专业学位）， 2019， 硕士

【摘要】 声波的探测与水声信号解调是水下目标探测系统的核心内容,随着目标隐身技术的不断提高,使得目标声波探测愈加困难,因此需要灵敏度更高的声波探测传感器。随着光电子学的发展,光纤声呐以其灵敏度高、损耗小,易于传输等优势应用于水下声波探测。然而,复杂的水下环境使得声呐探测信号中夹杂着大量的强噪声,因此,迫切需要一种新的低信噪比水声信号解调方法。混沌系统因具有高度的参数(频率、相位、振幅)敏感依赖性及噪声免疫,因此应用于低信噪比的声呐弱信号检测技术研究具有较为现实的工程意义。相对于传统的解调方法,混沌解调技术可以明显提高解调精度,降低解调信噪比门限。本文利用Duffing混沌系统实现强噪声背景下光纤声呐微弱信号参数的探测和解调。本文首先分析了直筒式马赫增德干涉型光纤声呐探测原理,利用Unigraphics NX软件进行建模,对直筒式的光纤声呐进行外部结构设计,并在LMS_Virtual.lab软件模拟水下环境进行光纤声呐传感器声波探测,根据理论设计的形状和尺寸,完成实验系统设计制作,采用实验设备对水下目标信号探测和参数识别。针对强噪声背景下水下声呐弱信号解调问题,利用混沌系统对信号参数的敏感性及对噪声免疫性的特点,结合尺度变换法提出了改进的Duffing混沌检测模型,制作新Duffing混沌系统信号采集电路板。采用Duffing混沌系统对水声信号进行采集,利用自制的光纤声呐与Duffing混沌解调模块搭建水下目标探测与解调系统,进行基于光纤声呐混沌解调技术水下目标探测系统的信号采集和信号参数实验研究。对光纤声呐接收的水下目标信号进行混沌电路解调,研究同强度不同频率声呐接收信号信噪比变化,以及同频不同强度条件下混沌声呐接收的信噪比和解调频率误差。结果表明基于混沌解调技术的光纤声呐信号处理方法具有极强的抗干扰能力和较高的频率辨识能力。更多还原

【Abstract】 Sound wave detection and underwater acoustic signal demodulation are the core content of underwater target detection system.With the continuous improvement of target stealth technology,the target sound wave detection becomes more and more difficult,so a more sensitive sound wave detection sensor is needed.With the development of optoelectronics,optical sonar is applied to underwater acoustic wave detection with its high sensitivity,low loss and easy transmission.However,the complex underwater environment makes the sonar detection signal mixed with a lot of strong noise.Therefore,it is urgent.A new low SNR underwater acoustic signal demodulation method is needed.Chaotic systems are sensitive to laziness and noise immunity due to their high parameters(frequency,phase,amplitude).Therefore,the application of low-signal-to-noise ratio acoustic signal detection technology has practical engineering significance.Compared with the traditional demodulation method,the chaotic demodulation technology can significantly improve the demodulation accuracy and reduce the demodulation signal-to-noise ratio threshold.In this paper,the Duffing chaotic system is used to detect and demodulate the weak signal parameters of fiber sonar in the background of strong noise.This thesis first analyzes the principle of straight-tube Mach-Zehnder interferometric fiber optic sonar detection,using Unigraphics NX software for modeling,external structure design of straight-type fiber optic sonar,and fiber sonic sensor sound wave in LMS-Virtual software simulation underwater environment detection,according to the shape and size of the theoretical design,complete the experimental system design and production,using the experimental equipment for underwater target signal detection and parameter identification.Aiming at the problem of underwater acoustic weak signal demodulation under strong noise background,using the sensitivity of chaotic system to signal parameters and the characteristics of noise immunity,combined with the scale transformation method,an improved Duffing chaotic detection model is proposed to produce a new Duffing chaotic system signal acquisition circuit board.The Duffing chaotic system is used to collect the underwater acoustic signals,the underwater target detection and demodulation system is built by self-made fiber sonar and Duffing chaotic demodulation module.The signal acquisition and signal parameters experimental research of underwater target detection system based on fiber sonar chaotic demodulation technology is carried out.The underwater target signal received by the fiber sonar is demodulated by chaotic circuit.The signal-to-noise ratio of the received signal with different frequency and the same frequency is studied,and the signal-to-noise ratio and demodulation frequency error of the received voice are obtained under the same frequency and different intensity.The results show that the fiber-optic sonar signal processing method based on chaotic demodulation technology has strong anti-interference ability and high frequency identification ability.更多还原