Research On Synchronous Data Acquisition And Transmission Technology Of Seismic Exploration Sensor Node

Shale gas and coalbed methane are unconventional natural gas,shale gas and coalbed methane stored in rock formations or coal seams as a highly efficient clean energy source and are a huge emerging industry in the energy industry.These clean energy sources can significantly reduce air pollution and improve the environment.The pre-exploration method of these resources is similar to oil exploration,the first ground exploration,the principle is to use the control source to generate the relevant source signal,and then by the high-precision sensor array(million or even million)to collect seismic reflection signal,The data through the specific geological model analysis can be used,to construct the three-dimensional structure of the rock;the second step through logging exploration,the sensor array into the deep wells(usually 3000 meters to 6,000 meters),and then through the long logging cable Return the collected data,and further analyze the resource reserves.In recent years,the rapid development of communication and network technology,and in the field of civilian has been widely used,but in the specific areas of resource exploration,for large-scale(million-level)node synchronization acquisition and transmission technology,and no Ready-made standards and specifications.In order to meet the requirement of simultaneous acquisition and low power consumption in all nodes in seismic exploration,we analyze the signal transmission characteristics from the cable transmission model and transmission theory,and propose a new physical channel data transmission method.The data transmission is obtained by simulation and calculation.The paper provides a fixed amplitude PWM forward pre-emphasis technique,which eliminates data transmission jitter from the transmission physical layer and provides a theoretical basis for high-precision data clock recovery between nodes.In order to improve the adaptability of the system,a fast algorithm is proposed to compensate the clock jitter problem,which solves the multi-level asynchronous problem of the seismic exploration node and satisfies the requirement of the same frequency work of the massive node.Based on the analysis of the principle of RS coding,this paper analyzes the generator polynomial and power consumption from the Galois domain,and proposes a coding method to adapt to the transmission of this system,which greatly reduces the power consumption of the system.In the data transmission convergence part,the double equalization model and the reverse tangent fast convergence algorithm are proposed,which solves the problem of low transmission speed of the long cable under the complex channel and satisfies the communication transmission problem in the super-long cable complex channel.On this basis,the successful development of single-chain 1000-level synchronous clock work of the node,the 1000 prototype of the prototype in Xinjiang Taklimakan Desert successfully tested,passed the acceptance of the Ministry of Science and Technology.Main Innovation:(1)On the basis of channel modeling,a forward PWM pre-emphasis method is proposed on the LPSDA line channel transmission.At the Nyquist sampling frequency,the maximum attenuation of 30 d B is obtained,compared to the 20 d B gain of FIR filter,the new method simplify the transfer functiona and easy to use FPGA implementation.(2)Several key problems of RS coding complexity in the seismograph are simulated from the Galois region,generating polynomials and multipliers,and an RS(31,27)coding scheme adapted to the seismograph is proposed.(3)Aiming at the problem of channel fading that affects the orthogonality of OFDM in long cable,a double equalization model structure and fast anti-orthogonality convergence algorithm are proposed.The correctness of the model is verified by simulation and experiment.,(4)We developed the relevant hardware,and tested it in the Xinjiang desert and Xi'an Qinling.The chapters of the paper are as follows:The first chapter is the introduction,elaborates the research background of seismic exploration,the research status quo at home and abroad,the research source of the research,analyzes the technical requirements of LPSDA large scale transmission system,and finally introduces the main research contents of this paper.In the second chapter,the communication mode of LPSDA system is described in detail,and the synchronous and asynchronous transmission frame format of the line direction is proposed.The influence of bandwidth limited channel on jitter of data transmission is analyzed.In the third chapter,the paper analyzes the line channel and its signal weakening in the LPSDA system.The Kramers-Kronig equation is used to analyze the distributed parameters of the cable.In the time domain,the dielectric loss and the convergence effect Impact on data transmission signals.In the fourth chapter,based on the analysis of model,the traditional pre-compensation model is analyzed,and the PWM pre-emphasis and SSF power compensation model are compared.On this basis,fixed amplitude PWM pre-emphasis scheme is proposed,which can effectively eliminate Clock jitter.In the fifth chapter,the coding and decoding layers of LPSDA system are analyzed.The influence of t / k value on the coding region of Galois field is analyzed by matlab simulation.On this basis,an improved low power RS coding method is proposed.Based on the analysis of FFE and DFE,a new method of double equalization model and fast tangent fast convergence is proposed,which reduces the error diffusion and simplifies the front structure.Through the matlab simulation,the optimized number of taps to enhance the system's bandwidth and channel capability is given.Chapter ? summarizes the technical indicators of seismic exploration,showing the physical prototype has been completed.Based on this foundation,the future of the system to expand and improve the proposed recommendations.