Design Of Electronic Stethoscope Based On MEMS Acoustic Sensor

With the continuous development of Marine science and technology,sonar buoy,as an effective tool for Marine information monitoring and scientific research,has the broad application prospect and rapid development in Marine scientific research and detection.The key research directions of the sonar buoy system are as follows:low cost of design and manufacture,high monitoring accuracy,low power consumption and great system stability.At the same time,the MEMS vector hydrophone developed by North University of China has the advantages of high sensitivity,high reliability,low cost,easily forming array and mass production,etc.Based on the consideration of all these above,A scheme of applying MEMS vector hydrophone and its array to sonar buoy system is presented in this paper.An underwater acoustic signal detection system is designed,which is the front-end system of the sonar buoy system.This system can be equipped with integrated 4-unit MEMS vector hydrophone,ciliary MEMS vector hydrophone or capacitive MEMS sound pressure hydrophone selectively.Based on the design of this system,three key technologies are deeply studied in this paper,which are shown as follows:the performance analysis and sensitive microstructure optimization design of integrated 4-unit MEMS vector hydrophone,the performance analysis and optimization design of weak signal conditioning circuit,and the design and fabrication of data acquisition and storage system.The main work of this paper is shown as follows:An annulus-shaped integrated 4-unit MEMS vector hydrophone(AFUVH)is designed and fabricated.Comparing with the ciliary structure 4-unit MEMS vector hydrophone,the sensitivity of AFUVH is improved by about 2.16db;The weak signal conditioning circuit integrated with MEMS vector hydrophone chip is designed and manufactured,which realizes the reduction of MEMS vector hydrophone background noise about 2-3dB;The design of the data acquisition and storage system based on FPGA is completed,which contains the hardware design of the system and the control logic compilation of each functional module.The sampling rate of this system is set at 4Ksps.This system realizes the acquisition and storage of 8-channel hydroacoustic signals with the frequency range of 5?1 KHz.Through the study of the key technologies all above,the design of underwater acoustic signal detection system applied to sonar buoy system is completed.This system not only provides an application platform for the experimental testing of MEMS vector hydrophone and its array,but also lays a foundation for its further engineering application in sonar buoy system.