Research On Key Technology Of Data Entry System For Towed Sonar Array

The 21 st century is the century of the ocean.With the increasing depletion of terrestrial resources,human beings begin to pay more attention to the exploration of the marine environment and the exploitation of marine resources.China is a large marine country.The development of the underwater acoustic technologies for marine exploration have an important significance for both national security and social economic development.Towed sonar array system is one of the representative devices using acoustic signal for underwater detection,which is widely used in underwater target recognition,oceanic oil and gas resources prospecting and other fields.Towed sonar array has the characteristics of large amounts of real-time acquisition data and long lasting operating time during data acquisition process,which put forward high requirements to the data entry subsystem's performance.In response to the needs above,this paper conducts deep analysis and researches focusing on the data entry subsystem,designing and constructing a highly reliable data entry subsystem.This essay's main contents and finished work are as follows:1.Introduced the working principle of towed sonar array detection system.Discussed the shipboard,underwater systems and other component modules of the sonar system in detail.According to the sonar system's data entry performance and reliability demands,this paper puts forward the data entry subsystem's software and hardware design scheme and discusses the key techniques to be solved.2.According to the system's designing performance indicators,the subsystem's high-reliability data entry card was designed after many comprehensive comparisons of various schemes.Selected the combination of PCI chip controlling DMA data transmission and data cache through external FIFO schemes for PCI board's design.A Shiduan module was developed to exchange data with the underwater system.The data entry card's backup circuits with two-stage switching control mechanism were designed to ensure the command and data transmission paths of data aquisitin card being backed up.3.According to the host computer software's functional demands and performance index,constructed computer software system based on Qt.Realizing the sonar system's acquisition control,underwater data's acquisition,display and standard format storage multifunction parallel execution by QThread technique.Underwater signal's waveform display,sonar system's information status display through Qwt and QCustomPlot widget.Store acquisition data through double-layer ping-pong structure mapping file technique.Achieved the data acquisition subsystem's backup paths switching control by host computer in fault condition.4.Analyzed the potential error situation in underwater data's uploading process,including data bytes,packets,data frames missing and data information changes.In the high-speed data acquisition card,established the error detection,compensating and correcting mechanism for data frame's structure missing and error.In the host computer,detecting and processing data information change error according to digital packets status information carried in data frames and the CRC check result comparison.5.Conducted experiments for the data entry subsystem in laboratory and field condition.In the laboratory,the system's data acquisition entry performance was verified through many experiments,including system data entry speed experiment,data transmission bit error rate experiment.PCI card and the host computer's error data detection and processing functions and back-up switching function were verified through simulative error data uploading from underwater nodes experiments.In the field condition experiments,the data entry system's various functions and the system's long-term reliability during the exploration process were verified through system's long time working experiments and experiments carried out at Tianjin Bohai Sea.