Research And Design Implemtation Of Wireless Communication System For Seismic Exploration And Monitoring

It is an essential process to use exploration methods to detect the distribution of resources before exploitation,because oil,natural gas and other resources need to be extracted from nature.Among the five kinds of geophysical exploration methods,namely gravity,magnetic,electric,seismic wave and radioactive,seismic exploration is the most widely used.This method uses artificial source to generate seismic wave signals,which are reflected or refracted by different strata structures,and then uses seismic data to reflect the strata structure and determine the distribution of resources.Seismic exploration system can be roughly divided into wired and wireless two types.In the early stage,the wired system was the main system,but with the continuous development of wireless communication technology,the wireless system is gradually replacing the wired system.Wireless seismic exploration system is a large-scale equipment that integrates seismic wave data acquisition,transmission,storage,processing,node positioning and condition monitoring technologies.The key of equipment research and development is the design of wireless communication system.In terms of relevant equipment research and development abroad,there are many manufacturers and the update is fast,while in China,the relevant technology is still in the research and development stage,and the degree of autonomy of equipment is not high and the update is slow.The wireless seismic exploration equipment needs to be improved and innovated constantly in order to adapt to the rapid demand change.Therefore,this paper designs a wireless communication system for seismic exploration and monitoring,and improves the key technologies of the system such as data transmission and node positioning.The work contents and innovations mainly include:(1)The seismic exploration operation area covers a large area,which requires a wide range of wireless network communication and high communication quality and efficiency.LoRa is a long-distance wireless communication technology.Although there is a relatively mature LoRaWAN protocol,it does not meet the routing communication requirements of mass nodes.This paper optimizes the communication protocol of the system networking based on LoRaWAN.During networking,nodes in different distance segments adapt different communication rates to improve networking speed.In data communication,different channels are divided into CSMA and TDMA,and the mixed access mode of CSMA and TDMA is adopted between nodes,which solves the problem of periodic and sudden parallel transmission conflicts.At the same time,the special communication protocol and networking communication process are designed,and the LoRa communication network is established to realize reliable data transmission.(2)Node positioning through the established LoRa network can reduce the difficulty of inspection for operators and improve work efficiency.The traditional three-sided measurement and positioning method based on RSSI ranging is easy to be affected by the environment.In order to adapt to the changing environment and improve the positioning accuracy,a triangular centroid positioning method based on fusion ranging is designed.The RSSI ranging model has the advantage of small error at the near end,while the TOA ranging model has small error at the far end.Dixon detection and EKF algorithm are used to eliminate the outliers of the two ranging parameters and then carry out ranging fusion to obtain the optimal distance estimate.In the actual situation,the ranging error is inevitable,the traditional three-sided measurement and positioning results will be in the triangle range,by solving the triangle centroid coordinates to achieve node positioning.(3)The monitoring center is far away from the operation area,and the gateway needs to be capable of ultra-long-distance communication to realize remote monitoring and management of the exploration operation site.Therefore,based on the above improved technical methods,combined with LoRa technology and 4G cellular technology to achieve wireless data transmission scheme,the software and hardware platform of seismic exploration and monitoring wireless communication system is designed and implemented,and the system is tested.The test results show that the improved method can significantly reduce the networking time and improve the communication quality,and the communication success rate is greater than 90%within2km.According to the triangular centroid positioning method based on EKF fusion ranging,the average positioning error is about 4.2m within 1km~2,and the positioning error is reduced by 25.5%.The average power consumption of monitoring nodes is only 4.83m W,which meets the expected requirements.