| Seismic exploration methods use seismographs to receive seismic waves excited by artificial seismic sources,which can intuitively understand underground geological structures.It has the advantages of large exploration depth and high construction efficiency,and plays an important role in the mineral resources exploration industry.With the increase in the demand for mineral resources and the decrease in easily exploitable resources,seismic exploration methods have increasingly higher requirements for exploration equipment."deep mining,intelligent mining,and green mining" are the three major development directions of our country's mineral resource mining concept in the future.However,in an area with complex geological conditions,the traditional cable telemetry seismic instruments are difficult to arrange and maintain with high construction cost and low exploration efficiency due to their huge volume and large line connection.Therefore,it is necessary to solve the technical problems faced by the complex environmental adaptability of seismic exploration instruments.The portable node seismograph is an integrated seismic acquisition system.Generally,an independent node completes the seismic data acquisition task by eliminating the cumbersome arrangement of large lines.In general,the internal battery supports the entire construction process without frequent replacement of the power supply module,which brings great convenience to the exploration work.Besides,portable nodal equipment also means more flexible exploration program design and wider exploration scope.Nodal seismographs are increasingly used in complex geological prospecting environments due to their flexibility in instrument arrangement,high-precision data acquisition,and high-efficiency construction.It is a new weapon for achieving the goal of "transparency of crustal structure".In the development of geophysical instruments and equipment,our country lacks systematic planning and organization as well as insufficient investment,which has led to long-term dependence on imported nodal seismic instruments.The domestic nodal seismic acquisition system has a big gap with foreign advanced instruments.When conducting large-scale seismic exploration in a complex geological prospecting environment,the existing instrument arrangement and field maintenance is difficult with low work efficiency.Especially in the passive source seismic detection method,the instrument is required to collect weak ground pulsation signals and exploration is required within a few days,the noise level and power consumption performance of existing instruments are difficult to adapt to new geophysical detection methods.In addition,most nodal seismic instruments use internal clocks for seismic data timing.As the time increases,the frequency drift of the crystal oscillator on the acquisition node will bring significant time error accumulation,so a wireless multi-node time synchronization method that is not limited by the number of nodes and exploration time in the large-scale seismic exploration environment is needed.The exploration process generally requires downloading and synthesizing through a data harvesting device to obtain complete seismic data for the nodal instruments.The acquiring of seismic data lags the acquisition process,which makes it difficult to guarantee data quality and construction efficiency.This paper analyzes the characteristics of the current nodal seismograph,conducts in-depth research on each key issue,designs and implements a low-noise,low-power weak seismic signal sensor system,a high-precision data synchronization method based on multiple nodes and a wireless data quality monitoring method based on energy balance,In addition,we developed the wireless low-power nodal seismic sensor system GEIWSR-? and verified the effectiveness and practicability of the new system through field application test.The main research contents of the paper are as follows:(1)Development of a high-precision seismic signal sensor system with low noise and low power consumption.First,the noise source of the analog signal acquisition channel is analyzed and the noise source direction is suppressed separately.A low-noise analog signal conditioning circuit is designed by using the minimum noise source impedance matching technology.Aimed at the comparison and selection of the current mainstream delta-sigma A/D converter,a high-precision data acquisition channel was designed.After the technical indicator test,the short-circuit noise level of the acquisition system is 0.8?V@500Hz,the dynamic range reaches 126.7d B@500Hz,the signal-to-noise ratio reaches 131.53 d B@500Hz,the total harmonic distortion level reaches 124.4d B@31.25 Hz.Aiming at the workflow and hardware structure of the nodal system in actual seismic exploration,the system dynamic power management technology is designed and implemented.The working process and power consumption of each hardware in the nodal seismograph are analyzed in detail,and the corresponding low power consumption control strategy was formulated,so that the instrument reaches the power consumption level of 162 m W@autonomous working mode and 291 m W@wireless monitoring mode.The average power consumption of the system reaches 198 m W in the normal seismic field acquisition mode when the working mode of the instrument is properly configured,which greatly increases the working time of the instrument in the field.(2)Research on wireless multi-node seismic data synchronization method with high-precision time-sharing index interpolation intercept.Aiming at the problem of multi-node time synchronization in large-scale and high-density seismic exploration methods,the current research status of nodal seismograph data synchronization is discussed,and the current time synchronization accuracy requirements and the hardware architecture of the node acquisition system designed in this paper are analyzed.A low-power time synchronization system using GPS and high-precision TCXO,the high-precision TCXO performs continuous data-timing with the GPS intermittent calibration to compensate for the time error caused by ADC clock crystal drift.In addition,this paper designs the precise time service flow based on GPS pulse second(PPS)interrupt GPS serial interrupt and the main program,which makes the synchronization accuracy between nodes reach 0.688?s.In-campus experiments have proved that synchronization stability is not affected by the location of sensor nodes and the number of nodes and detection time,which indicates that the time synchronization method has strong practical application capabilities to meet the time synchronization requirements of large-scale,high-density seismic acquisition tasks.(3)A hybrid communication system and wireless data quality monitoring method that meets complex terrain,large-scale seismic exploration,and reliable data transmission.Aiming at the limitation of large-scale and intensive seismic exploration that cannot effectively monitor the quality of data,a hybrid communication system based on core networks and extended multi-hop networks is proposed.A Wi-Fi wireless communication unit based on long-distance and high-speed data transmission is designed in the core network architecture and the low-power Zig Bee wireless communication unit performs short-distance data transmission in the extended network architecture.According to the proposed network architecture,the network simulation model is designed,and the MVWCRM method is proposed to balance the network load and energy.The node status data fusion technology and wireless data quality monitoring method are designed based on the MVWCRM method.Simulation experiments show that the MVWCRM method can continuously adjust the weights of energy influencing factors during the entire network cycle according to the distance between the cluster head node and member nodes and the changes in the weight of the remaining energy influencing factors of the node,so that the energy of the entire network is more balanced.In the network performance comparison test,the method proposed in this paper decreases the network energy consumption by 35% and 12%compared with the LEACH method and the EEUC routing method,respectively.The test of the wireless data quality monitoring method shows that when the data extraction factor e is 0.2,the monitoring data with a fidelity rate of 99.44% can be obtained,which greatly reduces the pressure of wireless monitoring data transmission and improves the exploration efficiency.(4)Based on the above-mentioned key technologies,a new nodal seismic instrument system GEIWSR-?,which integrates signal pick-up,data acquisition,multi-node data synchronization,and wireless data quality monitoring system,has been developed.Through the cooperation with GEIWSR-? system(a representative non-cable seismic instrument developed by Jilin University)conducted comparative tests,and the results showed that the equivalent noise level of the new system was decreased from 1.2?V@500Hz to 0.8?V@500Hz,the average power consumption was reduced from 500 m W per channel to 198 m W,and the data synchronization capability was increased from 10?s to 0.688?s.A wireless data quality monitoring system based on energy consumption balance is added,which solves the technical defects of the closedness of the instrument.Finally,using the wireless low-power sensor system GEIWSR-? proposed in this paper and the relatively stable SE863 portable distributed telemetry seismic exploration system,a joint exploration and comparison experiment was carried out in Chaganhua Town,Song yuan City,Jilin Province.Experimental results show that the quality of the data collected by the GEIWSR-? system is comparable to that of the Sercel 428 XL system.Compared with the SE863 system,the GEIWSR-? system has a higher data resolution.In terms of instrument portability and construction efficiency,GEIWSR-? has greater advantages over Sercel 428 XL system and SE863 system.In summary,the GEIWSR-? system has the characteristics of portable equipment,low power consumption with low noise,high time synchronization accuracy and stable wireless data quality monitoring performance,which greatly enhances the core competitiveness of the nodal seismic exploration equipment.It laid the foundation for performing large-scale and intensive seismic exploration in a complex geological exploration environment. |
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