Research On VLF Seismic Wave Detection Based On Stochastic Resonance With Lévy Noise

Building a strong ocean country is an important part of the cause of socialism with Chinese characteristics.In the new era of socialism,it is necessary to establish a strong navy.Passive detection of underwater targets is a prerequisite for obtaining operational advantages.With the underwater vehicle degaussing,noise reduction and other measures continue to improve,its own self-protection capabilities continue to improve,especially quiet submarine unmanned submarine underwater vehicles such as moving target radiation noise and echo characteristics The continuous weakening has greatly increased the difficulty of conventional methods in detecting underwater targets such as underwater vehicles.The very low frequency seismic wave signals,as the key signals for underwater large vehicles to detect signals and carry underwater targets,are not affected by hydrological conditions The spread through the sea floor,with a slow decline,the role of long-distance and difficult to be suppressed.Therefore,the underwater target detection using very low frequency seismic wave signals is an effective technical means for remote detection of underwater vehicles and is one of the key development directions of the remote sensing target of underwater passive detection systems.Aiming at the low signal-to-noise ratio(SNR)detection of very low frequency seismic signals under complicated marine low-frequency environment noise,this paper studies the weak signal detection method based on nonlinear stochastic resonance,in order to improve the capability of detecting and extracting the key features of a complex ocean environment?The main research contents and innovations of this paper are as follows:(1)An ocean VLF environment noise model with Lévy is established,and a parameter estimation method of Lévy based on logarithmic moment is given.The various sources and characteristics of marine VLF environmental noise are analyzed.The Lévy model which is more in line with the actual situation of complex ocean environment noise is established.The generation method of Lévy noise is further studied and compared with the measured low-frequency complex environment noise.The Lévy model is verified to describe the accuracy of ocean low frequency environment noise and rationality.(2)A scheme of using stochastic resonance method to detect VLF seismic wave signals under complex marine environment noise is proposed.The bistable stochastic resonance system with Lévy noise excitations is studied and the stochastic resonance system with Lévy noise is improved.The simulation results show that the output stability and frequency applicability of the second-order system are better than the first-order system,Order stochastic resonance method to carry out the follow-up study.Finally,the output performance of the second-order bistable stochastic resonance system under different parameters is compared,which shows the feasibility of improving the system output performance by adjusting the system parameters.(3)The second-order matching stochastic resonance detection method under the background-dimensional background noise is proposed.According to the conditions of stochastic resonance and the optimal signal-to-noise ratio of the system output,the matching parameters of stochastic resonance system under the dimension-line noise are deduced.Based on this,we establish the faint frequency of the VLF based on the matching stochastic resonance signal detector,the system output simulation experiments and testing performance simulation experiments show that the proposed system parameters matching stochastic resonance compared to non-matching parameters of the system output performance advantages,and finally with second-order bistable matching stochastic resonance The comparison between the detection system and the detection performance of the direct detector and the correlation detector verifies the feasibility and effectiveness of the second-order bistable matching stochastic resonance detection in the complex background noise.(4)Designed and built a VLF seismic wave detection test system.The experiment of outfield lake test was carried out in a Zhanghe River in Hubei Province.The experimental results verify the feasibility and effectiveness of the second-order matching stochastic resonance system in the detection of VLF seismic waves of underwater vehicles under complex marine low-frequency environment noise.