The Development And Calibration Of Plane Vector Sensor Array

With the development of modern technology,the general radiation noise levels of surface ships and submarines are kept decreasing.For modern quiet submarines,the overall noise level of which is the same as marine environmental noise.But limited by current noise damping technical conditions,the radiated noise in frequency range lower than 500Hz is still very strong.Though the traditional pressure hydrophone array can effectively detect low frequency and low noise level target,but their volume are too large and not convenient for use.To meet the need of low noise level target detection in long distance,we need a kind of small scale array instrment with strong low noise level target detection ability,and very convenient for engineering use.Vector sensor can answer this requirment.Vector sensor not only can measure the pressure value in sound field,but can at the same time also directly measure the amplitude and direction of particle velocity of sound,thus get more information from the sound field,which not only improved the underwater acoustic system’s performance,but also increased methods for signal processing.Vector sensor has many advantages like small volume,frequency-independant cosine directional character,and ability of isotropic noise suppression,these advantages provided new idea and improvements for low noise level target detection at low frequency.In this paper,the development process and current situation of vector sensor and vector sensor arrays are reviewed firstly,then a nine elements vector sensor array with 1/6 wavelength spacing is developed and calibrated,and the elements of which are cylindrical co-vibration vector sensors.According to the problem of making small scale high sensitivity cylindrical co-vibration vector sensor,the working theory and design method of cylinder vector sensor is studied.Through theoredical analysis and Comsol finite element simulation,the structure design of small scale cylindrical co-vibration vector sensor is optimized.And the suspension system is connected with the inside wall of element shell,to make the vector sensor easy for use,thus the vector sensor can be fixed on some basement.9 vector sensors were designed and fabricated with working frequency bands 20-500Hz,and acceleration sensitivities 3V/g.The sensitivities and the directional characters of sensors were calibrated in standing wave tube calibration system.The calibration result shows that every sensor has a good cosine directional character in its work band,and the sound transmission property of polyurethane shell is about 17dB better than steel shell.Then polyurethane shell is selected for vector sensors,and a plane vector sensor array with 1/6 wavelength spacing between each element.Due to the small spacing between elements,there have been mutual scattering,which strongly influence the signal phase measurement.A new phase calibration method,using amplitude of received signal for phase difference calculation,and calibrated the plane vector sensor array in laboratory as well as in lake.The calibration result proves the accuracy and effectiveness of this method.