Design And Implementation Of Digital Geophone System Based On FPGA

Seismic exploration is one of the most effective means in oil exploration, which plays an important role in the detection of oil reserves. For our existing exploration techniques and the less developed situation of digital geophone, this paper proposes a digitized design scheme based on traditional moving-coil analog geophones. We integrate the moving-coil geophone, data acquisition and transmission circuits and power together, so that the analog seismic signal detected by the vibration sensor can be directly converted to digital signal inside the geophone terminal, which eradicates the long-distance transmission of analog signal, enhances the anti-jamming capability of the system and improves the signal to noise ratio of the data acquisition.Based on the analysis of the seismic geophone’s working principle and the detector’s technical requirements of high-resolution seismic exploration, this paper presents the overall design of digital geophone system based on FPGA in detail. We has completed the design, production and debugging of the hardware and the system software programming.Finally, we set up the collection test system in the lab, and completed the data acquisition,transmission and storage of ten collection nodes with the use of the simulated seismic waves generated by the vibration table. The design uses the low-power, highly integrated FPGA of Altera’s Cyclone IV family as the main controller, and the SOPC embedded technology to control the whole digital geophone system, which reduces the size of hardware circuit design and the complexity of the software design. The system uses the high-precision 24-bit Σ-Δ ADC in signal acquisition, which well improves the resolution and dynamic range of the data collection. The data transmission section uses the communication technology based on PoE(Power over Ethernet) principle, which realizes the multiplex of the power and signal lines, and reduces the weight of cable. We implement the custom transmission control protocol by way of hardware logic, which improves theefficiency and flexibility of data transmission. Power conversion part is implemented by the high-efficiency isolated flyback switching power supply, which reduces the power consumption of the whole system. Meanwhile, the system also has functions of power monitoring and power transmission control, self-test, and environment measurement.The results show that the digital geophone has the advantages of low power, low cost,high dynamic range, small size, etc. The system can well complete the data acquisition and transmission control of the low-frequency seismic wave from 10 Hz to 200 Hz at the data transmission baud rate of 2Mbps, which lays an experimental foundation for the further application to the actual geological exploration projects.