Design Of Sonar Signal Acquisition System Based On FPGA

Sonobuoy is a kind of underwater target detection equipment widely used in modern naval anti-submarine warfare,which is mainly used in the early stage of large-scale search in antisubmarine warfare.Sound waves are currently the only known form of energy that can propagate over long distances in water.With the increasing number of underwater and surface vessels and submarines in the ocean,the acquisition system of sonar buoys has gradually evolved from single channel to more complex multi-channel synchronous acquisition,and high-precision integrated circuits are gradually used for signal processing and transmission.Therefore,for the development of sonar signal acquisition systems,miniaturization of hardware,real-time performance,and sonar signal processing algorithms are key research topics in the field of underwater acoustic acquisition.This article combines the development requirements of a certain type of aviation sonar buoy core acquisition system,and designs an underwater acoustic signal acquisition system applied in the electronic cabin under the sonar buoy.Design the overall scheme of the sonar signal acquisition system according to the project indicators.In order to ensure the miniaturization of the hardware platform of the acquisition system and facilitate subsequent upgrades,the hardware adopts modular design and circuit simulation.The filtering and partial gain in the signal conditioning circuit are designed with adjustable range,suitable for various occasions.The highly integrated design adopts the Cyclone IV series FPGA(Field Programmable Gate Array)as the core,completing functions such as acquisition control,data acquisition,caching,and forwarding,improving the reliability and stability of the system.The underwater environment is complex,and in response to the problem of noise in underwater acoustic data collection,the wavelet improved threshold method is used for denoising.The CW pulse wave model is used as the underwater acoustic signal,and dual mode noise is used to simulate the underwater noise in the collected signal.In order to facilitate real-time analysis of sampled data,QT is used to develop a collection system upper computer for receiving and processing the collected data,drawing the waveform of the sampled data and LOFAR(Low Frequency Acquisition and Recording)spectrogram,which can better display the relationship between frequency and time in the signal.The overall testing is divided into laboratory testing of hardware and software system modules,as well as testing of the system’s overall noise reduction pool.After analysis,the hardware system can meet the hardware design requirements of the sonar signal acquisition system for the electronic cabin under the sonar buoy,and the system can operate stably.The test results show that the sampling rate of the sonar acquisition system is 128 k Hz,the AD sampling accuracy is 24 bits,the amplitude error between channels is less than ±2%,and the phase difference is within ±0.5°.The improved wavelet threshold denoising algorithm has better denoising effect on seabed signal acquisition than the wavelet soft and hard threshold method.All performance indicators meet the design requirements,and this scheme can be used for practical applications.