Research Of Network Time Synchronization In Wired Telemetry Seismograph

With 30 years of economic growth, China’s energy, environment and other issues have become increasingly prominent. The sustainable supply of energy has seriously affected the economic growth of the country. In order to reduce the influence of energy shortage, China has carried out geological exploration, the exploration of scientific research project.At present, seismic method is an effective means to detect the deep Earth study. By artificially controlled seismic wave acquisition, and analysis of this data, the construction can foresee scientifically geological conditions, which can further avoid inrush of water, gas, and weak rock collapse and so on. Ten thousand or even more than one hundred thousand large seismic exploration system has been widely applied to the seismic exploration, the poor synchronization accuracy in seismic data acquisition system will cause a series of error in the late data analysis, which makes data analysis results less credible, and it may affect the rationality and assess the safety of the project, and finally become a serious threat to life safety and property damage.Jilin University has independently developed the cable telemetry seismograph GEIST-438 using Ethernet topology Relay communication between the data acquisition station. The synchronous mode of this seismograph is Ethernet synchronization technology which has high synchronization accuracy, but the synchronization accuracy seriously affected by the transmission distance. Communication line between stations contains two clock synchronization lines, so it inevitably increases the complexity of the hardware. In this paper, based on wired telemetry seismograph GEIST-438 network, it is proposed a new set of seismograph network synchronization system.Reference Ethernet synchronous technology, such as NTP and IEEE 1588V2, independently design a new set of network time protocol. Since the data communication is based relay topology Ethernet of wired telemetry seismograph GEIST-438, transfer clock packet is severely affected by network traffic. The article by introducing statistical methods and transparent clock synchronization concepts, innovatively designs synchronization compensation and transparent clock compensation algorithm, and further improves the accuracy of time synchronization. For the realization of fast time hack in the large-scale seismic exploration systems, the paper introduces multi-threaded server technology, thereby controlling each request seismic acquisition systems efficiently to achieve rapid and orderly time hack.The hardware testing system is built in the lab, and the network synchronization method is tested. The test results show that the Multi-thread concurrent server can effectively improve the efficiency of synchronization and the synchronization accuracy can be up to two hundred micro seconds in small acquisition system, matching the requirement of 2KHz sampling rate. MATLAB software is used to realize the synchronization precision and seismograph units, and consuming time and seismograph units of curve fitting. According to the fitting results, the article analyzes the synchronization technique based on network allows to set the maximum seismic instrument units, and the maximum consuming time for synchronization. The test results meet the design requirements, and verify the feasibility of the network synchronization in Wired Telemetry Seismograph.