Underwater Target Detection System Based On Fiber-Sonar Chaotic Demodulation Technology

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.