Design Of Underwater Low Power Modular Data Transmission System For Deep Sea Seismic Long Cable

With the proposal of China's marine oil and gas resources strategy,marine geological exploration will develop in the direction of deep sea and deep strata.In the current marine seismic exploration,the length of the underwater streamer of the streamer system is insufficient,and the density of the detector is insufficient,and the demand for deep-sea geological exploration cannot be met.Therefore,it is urgent to upgrade.Because the structure of the underwater data transmission platform of the streamer system in the previous marine seismic exploration was solidified and the transmission mode was simple,hardware redesign was required during each equipment upgrade,and the development cycle was long and the cost was high.In addition,the high power consumption of the data transmission system limits the number of underwater data transmission systems,further limiting the increase in the length of the underwater streamers.In the face of the long-haul cable system of the deep-sea earthquake long cable system,the situation of more transmission nodes is that the transmission rate of the existing underwater data transmission system cannot meet the system requirements.In view of the incompatibility and inconvenience of underwater transmission platforms for marine seismic exploration into the streamer system,a long-distance transmission and remote download and update of the data transmission common platform have been studied.The transmission platform adopts a modular idea and divides the hardware structure into four units of data acquisition,driving,receiving and processing.Each part is designed separately.When the different transmission schemes are demonstrated,only a partial replacement of the structure is required,and the generalization of the data transmission platform is achieved.Based on this general structure,an underwater transmission platform was designed.The platform uses FPGA as the control and data processing core.The front end uses a 24-bit Sigma-Delta ADC for sampling and uses the Serdes method for long-distance transmission.The full text is divided into seven chapters:The first chapter is the introduction.This paper mainly introduces the background and significance of deep sea long cable system research,the research status of offshore towline system at home and abroad,summarizes the deep sea seismic long cable system and underwater data transmission system,and proposes the design goal of digital transmission package,and the paper Research content and structure.The second chapter is the study of the overall scheme of data transmission.The transmission medium in long-distance transmission is mainly introduced.The influence of cable on the signal during long-distance transmission is analyzed.The transmission line suitable for marine seismic streamer system is selected.Finally,according to the characteristics of the data transmission package,three feasible transmission schemes are proposed.The power consumption of the three schemes is compared from the transmission physical layer chip,and the LVDS transmission scheme with pre-emphasis and equalization is selected.The third chapter is the modular design.Based on the long-distance LVDS transmission scheme,the data transmission system is divided into modules according to different functions.At the same time,combined with the size of the"electronic cabin"to be installed in the digital transmission system,each functional module is mapped to the structural module.Finally,according to several connection methods that may occur between the modules,the interface between the modules is standardized,and the modular idea is actually The circuit board has been well applied during the development process.The fourth chapter is the hardware circuit design and implementation.It mainly introduces the design and implementation of the main hardware circuit of the transmission system,such as low-power selection and circuit implementation of digital packet transmission power supply,core processing unit,pre-emphasis adaptive equalization module,serial-parallel and parallel serial devices.At the same time,the peripheral circuit design such as clock and Flash ROM is introduced.The fifth chapter is testing and analysis.The test environment is introduced according to the power consumption and transmission design goals of the data transmission package.The hardware logic for transmission error rate and transmission system interconnection test is written,and detailed test is carried out from the aspects of overall transmission performance,data transmission packet power consumption,long-term transmission error code test,transmission system interconnection test,etc.,and the results are analyzed.The sixth chapter is the summary and outlook.Mainly summarized the work content,refined the innovation of the paper,and the prospect of follow-up work.