| The shallow seismic exploration was one of the most widely used and best effective Method that solving the all kinds of engineering,hydrology and environmental geological problems.And this is the puzzle faced by the traditional equipment hard to meet demand of the gradually harsh exploration environment and ever-expanding exploration realms,the key for solving the problem is to improve the acquisition performance of shallow seismic exploration equipment.However,acquisition performance is a comprehensive and systematic concept,which is difficult to achieve by breaking through a single technical index.Focusing on solutions to this problem,this article start with an approach from the latest developments in digital seismic exploration method,in the view of the domestic mainstream shallow seismograph is widespread digital improved digital method of the system structure drawbacks,actualize the acquisition accuracy,resolution,the overall ascension of portability,performance and tailorable.And through by research,the main research achievements are as follows.:(1)Take aim at the problems such as signal attenuation and inter-channel crossta lk caused by the long transmission distance of analog signals of traditional analog ge ophone,this paper adopts the design idea of all digital,and actualize the all-digital s ignal acquisition unit by through the development of low-power microcontroller,24-bi t A/D conversion unit,low-noise signal conditioning,and configurable gain unit and bus-based data transmission.At the same time,Integrates a programmable delay co mpensation,transmission and self-inspection units are integrated,the acquisition units work independently,it through the digital communication,the crosstalk problem of int er-channel signals is effectively reduced,and improved the transmission distance of si gnals.(2)Focus the working mode and practical application requirements of digital sha llow seismic exploration,this article uses the modular separate thinking to construct t he hardware architecture of "PC terminal" + "digital acquisition station" + "digital geopho ne".The off-line control between the terminal and geophone with full digital operation significantly enhance the stability of the system.(3)For the requirements of field portable construction and network transmission of multi-node seismic data,this article has independently designed a large-capacity se ismic data transmission network based on the "ethernet-RS485",ethernet’s may cut ou t of excellent data transmission capacity of network architecture by taken advantage o f network capacity and RS485 fieldbus control capacity,it greatly improving the syst em network capacity and expandable trace number.After the test,the geophone can be independently operated without affecting each other and can be clipped at will.In the field,when the actual shallow seismic exploration task is performed,the collected waveform is clear at the beginning and the takeoff was obvious,and data packet los s is rare circumstance,meet the demand of field multi-node seismic data network transmission.Test the system prototype of complete functional,the results show that the syste m equivalent noise below 1μV,synchronous accuracy is better than that of 10μs.the gain accuracy is higher than 1%,the harmonic distortion is less than-100 dB,acquisi tion bandwidth up to 4kHz,and dynamic range is greater than 130 dB,the machine p ower consumption is lower than 45 W,various performance indexes reach the domesti c advanced level.At the same time,In the actual shallow exploration area compared with traditional instruments collection experiment shows obvious advantage,not only on the resolution and signal fidelity ability better,but also has small volume,light q uality,scalable maintainability and other advantages,It provides a kind of solving wa ys about higher quality reconnaissance to the shallow earthquake’with important scient ific significance both the value of application. |
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