Research On Inverted Echo Sounder

The marine environment is influenced by many factors such as wind,waves,tides,temperature,salinity,light,and nutrients,with fast and complex changes,which poses high requirements for ocean observation.Marine sound propagation is affected by ocean waves,changes in ocean pressure,and other factors.Observing the echo propagation time can obtain relevant marine information.In this study,an inverted echo sounder was designed and implemented to carry out observations and inversions of deep sea temperature-salinity profiles and shallow water effective wave heights.The analysis of the inverted echo sounder is the basis of this research.The study analyzed the propagation and loss characteristics of acoustic signals in seawater,and conducted comparative analysis on the electro-acoustic characteristics and driving schemes of transducers for the transmission and reception of acoustic signals,as well as the amplification and detection schemes.Based on the analysis,the design ideas for the electronic circuit part of the inverted echo sounder were determined.The design of hardware and software is the core of the research.In the hardware design,the power amplifier circuit section and the control circuit section were designed through the analysis of IES.The power amplifier circuit includes a driver voltage regulation circuit,a transducer driver circuit,and an echo signal amplification and detection circuit.The control circuit includes a master-slave controller,as well as relevant voltage,current,attitude,temperature,and pressure sampling circuits,data storage circuits,external RTC circuits,positioning,communication,and other related circuits.In the software design,based on the workflow,software design was conducted for the master-slave controller using the Switch-Case state machine and Free RTOS operating system,as well as for requirements such as measurement,storage,release,instruction communication,and others.The validity of the design scheme was confirmed through actual circuit verification,and prototypes were manufactured and used for oceanographic survey experiments at stations near the Dongsha Islands in the South China Sea.The experiments collected continuous propagation time and bottom pressure data for more than two months.Combined with historical CTD data and the geostrophic empirical mode(GEM)inversion,temperature and sound velocity profiles were obtained as time series,which verified the validity and reliability of the design scheme.Finally,an oceanographic survey experiment was conducted near the Jiaozhou Bay Zhongsha Reef Lightship,and about a week’s worth of data was obtained.The data accurately reflected changes in significant wave height in the experimental area.The coefficient of correlation between the temporal dispersion of wave propagation and the local significant wave height at the time was as high as 0.84.Based on this,an inversion method for significant wave height was proposed,and the percentage variance between the inverted significant wave height and the actual significant wave height reached 88%.This proves that the equipment can measure significant wave height and has further research value.