Development Of Seismic Source Synchronous Control System For Seismic Exploration Based On Heterogeneous Wireless Networks

The source synchronous control system is an important part of seismic exploration equipment.Its main function is to ensure the synchronization of the source excitation time and the seismic data acquisition start time.Whether the precise synchronization can directly affect the accuracy of seismic exploration.Aiming at the shortcomings of complex synchronization scheme and difficult system construction in traditional source synchronous control system,this thesis proposes a seismic source synchronous control system for seismic exploration based on heterogeneous wireless networks.The main work completed includes:(1)Hardware selection and circuit design of system nodes.Including the hardware implementation inside the module and the communication connection between the modules;(2)Software design and function implementation of the system.Including the design and implementation of the overall structure of the system heterogeneous wireless network,and customizing a data communication format for the seismic exploration system to complete the control of the entire system synchronization process;(3)Based on the analysis of the working principle of the existing source synchronous control system,a post-synchronization scheme is proposed to realize system synchronization;(4)Based on the post-analysis synchronization scheme,a source excitation detection method based on continuous threshold and derivation and a system node clock synchronization method based on Pulse Per Second(PPS)time-scale frequency measurement are proposed.Compared with the traditional source synchronous control system,the seismic source synchronous control system for seismic exploration based on heterogeneous wireless network proposed in this thesis has the following advantages:(1)Design of wireless transmission scheme based on heterogeneous network.The traditional source synchronous control system completes the communication between the system nodes through the radio station.In this thesis,the low-power self-organizing network is used to complete the communication between the decoder and the gateway/encoder node,and the wireless LAN Wi-Fi is used to complete the communication between the gateway/encoder node and the host computer,while ensuring the communication function of the system,not only reduces the power consumption and cost of the system,but also enables the communication system to have the networking capability,which can better adapt to the harsh seismic exploration surroundings;(2)Post-synchronization scheme design.The traditional source synchronous control system can achieve synchronization accuracy of about 20?s by synchronous timing control.However,the synchronization process of this scheme is complicated,and manual intervention before construction is required to complete the measurement and compensation of various delays of the system,which increases the construction difficulty.In view of these shortcomings,this thesis proposes a post-synchronization scheme,which is to detonate under the premise of ensuring that the seismic data acquisition node has begun to collect,and then transmit the collected accurate source excitation timing back to each seismic data acquisition node.The data acquisition node locates the storage location of the seismic data when the source is excited,and uploads the valid data.The post-synchronization scheme is simple in method,and the synchronization process does not require manual participation.The synchronization error of the system is within 250?s,which satisfies the synchronization accuracy requirement within lms of the source synchronous control system.