The Research And Design Of VSP Acquisition System On STM32

VSP technology is superior to surface seismic exploration technology in itssignal-to-noise ratio seismic data, high resolution, and the kinematics and dynamicsfeatures of the wave. VSP technology has been successfully applied to energyexploration, but in engineering exploration, it is seldom used. Thanks to their similarexploration principle, the technology advantage and structure characteristics of VSPacquisition device in energy exploration can be a reference for research anddevelopment of shallow VSP equipment applied in engineering exploration. Currently,the development of shallow VSP logging instrument present the following trends,mainly in the detectors, the change from the traditional moving coil type or thepiezoelectric mechanical sensor to MEMS acceleration sensor, from single componentto three components development, from analog transmission into digital transmissionmode in data transmission. However, now most of the equipment used extensively inengineering seismic exploration is imported in high price. Therefore, it is verynecessary to develop VSP logging system with proprietary intellectual property rights,which has a broad prospect of application and vendibility.This paper first elaborates on VSP exploration technique method, includingmany of the advantages in application to geophysical exploration, its developing andequipment research and development at home and abroad. Then under the guidance ofthe mature principle, the writer embarks on the research and development of shallowVSP acquisition system. The whole design adopts modular ways, primarily dividedinto the design of the underground detectors collection node, main control systemdesign on surface and the design of the control software. The whole VSP collectionsystem, taking RS485communication network as the link, is responsible for all kindsof control instruction and the transmission of configuration information and theseismic data to coordinate the normal operation of the whole system. This paper focuses on the introduction of the hardware part of the instrument. After more thanone year’s research, here are the achievements:(1)The completion of the design of underground detectors collection node.Underground collection node is designed by the flow of seismic signal, and its maincontrol center adopts the most advanced STM32micro controller of Cortex-M3kernelproduced by ARM, and uses MEMS acceleration sensor with testing function assignal acquisition unit; Op-amp LM4562is taken as the preamplifier to magnify theweak seismic signal; The24bits ADS1255chip based on Σ-Δ technology by TIcompany, with a low noise and high resolution, are applied to transform analogsignals into digital signals; Furthermore, the selection of ADM2582E as the driverchip of RS485bus, has constructed the data transmission network on the basis ofRS485serial communication standard which has the characteristics of big dataquantity and strong anti-interference ability, and realized the expanding and cutting ofnetwork nodes, and realize the correspondingly complex communication protocol;The design of DC motor driver circuit and the power management solution withstability, high efficiency, low ripple are also finished.(2)The completion of the ARM9mainframe design of the Windows CE operatingsystem aboveground. In the design, the control host computer aboveground withS3C2440micro controller made by Samsung company as the core, is equipped withsuch circuits as the SD card interface, master-slave USB interface, debugging serialport, touch screen interface, RS485communication interface, etc.and loads theWindows CE operating system, meanwhile,based on which the relevant controlsoftware is developed too.To sum up, VSP collection system, after further improvement of software, can beapplied in the field of engineering exploration like shallow VSP exploration.