Research On Excitation Optimization And Spectrum Characteristics Of Underwater Active Electric Field Detection Method

At present,the development of marine resources is mainly focused on the shallow water depth.With the relevant research of biologists on a kind of fish with the ability of active electric field detection,combined with the development of electric field detection sensor technology,the detection and positioning technology based on underwater active electric field has gradually come into the vision of scientists and engineers.In addition to the research on the theoretical principle of weak electric fish using active electric field detection,some researchers began to apply underwater active electric field detection and positioning technology.The focus of the thesis is to detect the object by synthesizing a multi-frequency signal which simulates the excitation signal spectrum emitted by weak electric fish and analyze the relationship between the object and the frequency response of the signal.Combined with the theoretical model and the underwater detection process of weakly electric fish using active electric field,an experimental platform based on underwater active electric field detection was built.Using the experimental platform and based on the principle of control variables,the fixed-point isolated measurement of experimental objects with different geometric shapes and different materials was carried out.The spectrum analysis of the measured signal was carried out,and the signal amplitude and phase information are discussed with the characteristics of the measured object respectively.The main contents of the thesis are as follows:1.The thesis expounds the biological principle of weak electric fish in underwater detection,and constructs the underwater active electric field detection model from the theories of electric dipole model and induced polarization effect with the help of the relevant theories of electricity and geophysics.2.From the perspective of signal transmitter,by analyzing the characteristics of single frequency sinusoidal signal and short-time pulse signal excited by different kinds of weak current fish in frequency domain,a multi frequency excitation signal with high amplitude in medium and low frequency band,low amplitude in high frequency band and frequency band close to the biological signal used for weak current fish detection is designed.The purpose is to optimize the harmonic component of the excitation signal,select the equipment and realize the excitation and emission function after optimization.Combined with the principle of underwater active electric field,multiple software and hardware modules are coupled to build an underwater active electric field detection platform.3.On the basis of the above principles and experimental platform,an underwater active electrolocation experiment based on synthetic multi-frequency excitation is designed and carried out to analyze the frequency response characteristics of the detection object using the optimized multi-frequency excitation.Based on the idea of control variables,the relationship between the shape of the measured object,the material of the measured object,the distance between the measured object and the electrode array and the response of multi-frequency excitation signal is comprehensively analyzed by using the fixed-point measurement method from two aspects of amplitude correlation information and phase correlation information.