Design Of Digital Hydrophone For Marine Seismic Towing System

The ocean contains abundant oil resources.Data shows that offshore oil resources account for 35% of total global oil resources.The natural gas hydrate,as a new kind of energy,has the characteristics of clean,environmental protection and high utilization rate.Survey results show that the East China Sea and the South China Sea are rich in natural gas hydrate resources.Now,the construction of marine engineering in our country is becoming more and more.Marine engineering survey and marine geological hazards survey both are necessary early works for ocean engineering construction.Seismic exploration is the most popular way of offshore oil,natural gas hydrate and marine engineering exploration.So conducting further study on marine seismic exploration equipment brings greatly theoretical significance and practical value.With the support of the national key research and development plan “deep-towing,high-resolution,multi-channel seismic exploration technology and equipment”(2016YFC0303901),the research and design of the digital hydrophone for marine seismic towing system are carried out in this paper.Digital hydrophone consists of two parts mainly: hydrophone;signal acquisition and transmission module.Hydrophone,as a kind of transducer,transforms seismic signals into electrical signals.A piezoelectric ceramic hydrophone is used in this paper.The signal acquisition and transmission module digitally digitizes the electrical signals outputted by the hydrophone,then transmits the digitalized signals to the relay data packets of the marine seismic towing system.The main content of this paper is the design of signal acquisition and transmission module.This paper starts with improving data acquisition performance and reducing system power consumption.It uses high-precision 32-bit ?-? ADC and low-power consumption microcontroller to realize high-precision data acquisition and low-power operation.The signal acquisition and transmission module of the digital hydrophone takes STM32L432 as the core,use SPI-bus to control four ADS1263 completing four-way seismic signal acquisition,adopt nine-axis attitude sensor to realize real time monitoring of towing,and communicate with relay data packets through the custom three-level communication model.The digital hydrophone acquisition and transmission module in this paper uses Free RTOS embedded real-time operating system to realize five basic tasks of the digital hydrophone for marine seismic towing system,including management of seismic data acquisition,attitude data acquisition,data packaging and uploading,command parsing and command processing.Management of seismic data acquisition task takes synchronization mechanism,based on synchronous command and synchronous clock,to realize synchronous acquisition of four-way seismic signals,including starting acquisition,stopping acquisition,sampling frequency setting and gain setting.The attitude data acquisition task has the function of real-time acquisition.Data packaging and uploading task realizes the function of real-time data uploading based on the ring queuing and DMA transmission technology.The command parsing task uses the finite state machine to implement the command parsing function.The command processing task implements the command processing function.According to the technical indicators,this paper has completed the related test experiments.The results show that the digital hydrophone designed in this paper has small self-noise,large dynamic range,high-precision of synchronous acquisition,and low-power consumption.The indictors have reached and partly exceeded the performance indictor of similar equipment abroad,which can be used for reference in high-precision signal acquisition in marine seismic exploration.