Design And Implementation Of Single-channel Storage Type Wireless Seismograph Based On STM32

With the development of modern economy and the continuous improvement of living standards, people’s requirements of resources are increasing. In order to solve the contradiction between the large population and limited resources, the exploration space should be extended from the shallow surface deep into the earth. Seismic exploration technique is a very effective geophysical technology for deep exploration.It has the advantages of wide exploration depth, high resolution ratio, high signal-to-noise ratio and good fidelity etc. At present, cable seismographs play a dominant role in the seismic exploration system. Cable transmission lines on seismic instruments control system synchronization and data transmission process, and this working mode is the main cause of long-term high cost of exploration. In order to reduce the cost of exploration, it’s necessary to break the traditional mode of seismic exploration. Therefore, wireless seismograph comes into being. Wireless seismographs use wireless communication technology to process data online or use storage medium to store data locally instead of seismograph transmission lines. In this method, field exploration system configuration can be simplified. It can reduce system cost of materials and transportation cost. It is a new option for future large-scale seismic prospecting exploration. In recent years, wireless seismograph has a rapid development in domestic but it is not widely applied to exploration and construction because of its high cost of hardware, great volume and weight.To develop a low cost and miniature wireless seismograph called single-station and single-channel storage type wireless seismograph, the design adopts a working style of each station acquisites one way of seismic data. Firstly, analyze the working mode of three kinds of wireless seismograph, and especially analyze the working mode and structure of wireless storage type seismograph. Based on the analysis of system functions, put forward the overall design scheme of single-station andsingle-channel storage type wireless seismograph and its hardware platform. Realize the system with high precision data acquisition technology, GPS timing and synchronization technology and embedded FTP server technology. The system uses STM32 as the core to build the minimum system working as the main control module of the system. Build signal pretreatment circuit with the analog switch ADG201, a RC filter and the differential amplifier THS4521, responsible for signal switching,filtering and signal conditioning. ADS1281 acts as the core of the signal acquisition circuit and it achieves with high precision, high fidelity and adjustable sampling rate.Use a four-line SDIO interface to drive an SD card, which guarantees to storage the data with a high speed. Use the GPS module to provide GPS timing and synchronization service, solving the problem of synchronous seismic data acquisition for distributed seismographs. In order to realize the function of network communication, integrate the network card chip DP83848 working as the physical layer chip. In the software development process, transplant Free RTOS into the instrument to ensure real-time of the system and realize the multitasking. In order to facilitate the operation of the SD card, transplant Fat Fs into the system. For the realization of the embedded network communication transplant a small TCP / IP protocol stack named Lw IP. Finishing the combined transplantation of Free RTOS and Lw IP, write network application layer program and build an embedded FTP server in order to download the seismic data.Finally, analyze and test the performance of single-station and single-channel storage type wireless seismograph. Analyze the miniature of model machine. Test the function of data acquisition, short-circuit noise and dynamic range of the system.Analyze the cost of the hardware for the instrument. Test the basic function of data downloading and especially test data downloading speed. The test results prove that this system is a low-cost and miniature seismograph with qualified performance.