Low Frequency Signal Receiving Performance Of Vector Sensor And Its Influencing Factors Analysis

With the continuous development of submarine vibration and noise reduction technology,the overall level of radiated noise is decreasing day by day,and has gradually approached the Marine environment noise.The working frequency band of passive detection based on its radiated noise shifts to low and very low frequency,while the vector sensor has become an important equipment in underwater target detection by its cosine directivity independent of frequency and its excellent characteristics of high sensitivity in low frequency band.However,in the process of use,it will be limited by various factors,such as the vector sensor itself selfnoise,resonant frequency,structural scattering and other factors,which can not effectively obtain low-frequency acoustic information,resulting in the vector sensor receiving performance decline,which has an impact on the accurate detection of underwater targets.Therefore,this paper studies the engineering difficulties faced by low frequency acoustic detection,takes low frequency signal received by vector sensor as the core,and analyzes the influencing factors such as the self-noise of vector sensor and the scattering of the platform or carrier where the vector sensor is located.This paper starts with the energy characteristic of vector sound field,and uses the relation between acoustic energy density and acoustic energy flux density to lay a theoretical foundation for distinguishing acoustic noise from non-acoustic noise.The non-acoustic noise can be obtained by the relation between sound pressure and vibration velocity of vector sensor.When evaluating the influence of various factors on the receiving performance of vector sensor,the vector sensor’s own self-noise is given priority as the classical non-acoustic noise.The optimal weighting of single vector sensor signal processing when non-acoustic noise is taken into account is analyzed.Secondly,in order to avoid the influence of the structural parameters of the vector sensor itself on the subsequent analysis,various performance parameters are studied,starting from the resonance point formed by the elastic suspension system on the vector sensor in the very low frequency band and the influence on the vibration speed measurement,and then the resonance point of the vector sensor itself is determined through the measurement of its sensitivity and equivalent self-noise to exclude the interference of intrinsic factors.Then,from the low frequency characteristics of the spherical structure scattered sound field,the spatial correlation function of the sound pressure and vibration velocity scattered by the spherical structure under the isotropic noise field is derived,which provides a theoretical basis for improving the processing performance of vector sensor array under the spherical structure.When spherical structure scattering exists,the ratio of vibration velocity components in θ direction and φ direction of vector sensor in spherical coordinate system is equal to a constant value.Based on this principle,the orientation information of target is evaluated.This method can reduce the influence of spherical structure scattering to a certain extent.Through the study of the vector sensor may be affected by adverse factors in the use process,the interference of non-target factors can be reduced to a certain extent,so as to further improve the quality of low-frequency signal received by the vector sensor,and provide certain reference value for low-frequency target detection.