Design And Development Of High Fidelity Digital Hydrophone Based On FPGA

Acoustic waves are the only effective carrier for transmitting underwater information.The sensors that receive acoustic signals are hydrophones.Traditional hydrophones are mostly analog hydrophones.It has the problems of weak output signal,complex test system and low signal reduction.This project designed and developed a high-fidelity digital hydrophone based on FPGA,which has the characteristics of low self-noise,wide dynamic range and high signal reduction.This article comprehensively compares the technical indicators of digital hydrophones at home and abroad,and focuses on the technical summary of low-noise preamplifiers.According to the general requirements for underwater acoustic receiving equipment in the field of underwater acoustics,the design goals and overall design of the digital hydrophone system are proposed.Based on the design index of digital hydrophone,the hardware circuit design and software design of digital hydrophone are introduced in detail.The system takes FPGA as the core and controls the high-precision ADC to collect underwater acoustic signals through the SPI bus.Control high-capacity storage module through high-speed LVDS,and control signal communication module to realize data communication with upper computer.In the hardware design,three different types of low-noise preamp circuits are analyzed and discussed.Through test comparison,the voltage preamplifier circuit with low noise JFET integrated operational amplifier as the core is selected.The system uses Lab VIEW software to design the relevant functions of the host computer program,and uses the digital equalization algorithm to correct the sensitivity fluctuation of the hydrophone,and realizes the high-fidelity restoration of the signal in a certain frequency band.The developed digital hydrophone was tested in detail for functions,noise,sensitivity,storage performance and other indicators.T Test results show that the designed digital hydrophone has a measurement bandwidth of 50 k Hz,in-band noise of less than 10 ?Vrms,sensitivity of-191.5 d B,in-band sensitivity fluctuation of less than 1 d B,and acoustic dynamic range of 96 d B.PC software has commonly used acoustic measurement functions.Digital hydrophone has certain application prospects in underwater acoustic measurement.