Design Of The Configurable Acquiring And Filtering System For Seismic Data Based On FPGA

Along with the development of modern electronic technology,the geophysical exploration technology gains continuous progress. The seismic exploration as the most important geophysical exploration method is also booming. Both the data collection technology and the instruments in upgrading all get a large degree of ascension.Field seismic data acquisition is the most important seismic exploration in the process, which includes the collection of seismic signal, the amplification of seismic signal and the filtering processing, signal beforehand storage. In the process of data collection, eliminating the interference, accurately gathering the need effective signal, is the key of the correct processing and later data interpreting. It's significant that how to efficiently combine today's advanced electronic technology with the seismic exploration technique. It's also the emphasis of research seismic exploration. This paper studies and analyzes seismic exploration situation and the developing trend of system. According to the precision of seismic data acquisition and real-time filtering process, the paper put forward the direction of the following three aspects for specific research contents of seismic data acquisition filtering system design scheme.(1)The filtering systems research of configurable parameters bases on FPGA. Combining with the different conditions of actual seismic data collection, This paper researched the filtering system which bases on FPGA configurable parameters. The filtering system consists of low-pass filter, high-pass filter and subsidence filter. According to the acquisition of the spectrum control, the system set up different cut-off frequency to filter the corresponding noise, guaranteed the high-speed data effectively during the corresponding transmission, while improving the signal signal-to-noise effectively. At the same time, it can improve the signal-to-noise ratio of the signal, increase the anti-interference signal. Basing on FPGA, the single chip of the system can accommodate transistor with more and more big in size, reducing the hardware design cost seismic exploration system. Its repeatedly programming, writing characteristic can adapt to the renewal speed of electronic technology nowadays. Its more and more powerful application functions can also greatly improve the performance of the system of the seismic exploration.(2)The preprocessing circuit design of the seismic data bases on the seismic data. Two-level programmable amplifying circuit bases on the PGA205, can amplify the precision of weak seismic signal, differential circuit bases on the AD8138, using the differential signal to transmit in order to improve the signal transmission anti-jamming and drive ability, coupling and isolating circuit bases on LM456 can enhance the stability of the whole circuit bus operation, A/D converter circuit ofΔ–Σoversampling technique which owns 24 bits high-precision bases on ADS1255 meets high dynamic range measurement requirements of seismic signal, multiplexing circuit bases on ISL84052, can reduce hardware cost of multi-channel data acquisition, the main controlling circuit bases on STM32F103ZET6 meet the needs of lower power consumption and more resources.(3)The design of the filter program. The program design of filter bases on FPGA adopted the ideas of bottom-up, and used the hardware description language (VHDL language) to design the related function module of filterThe progresses derived from the thesis are as follows:(1)Designing a seismic data pretreatment system circuit, which helped to achieve amplification, isolation and anti-jamming of the seismic data, each function circuit owns higher precision and reduced the interference of the multilevel circuit. The error in difference conversion drive circuit is under 1%, the greatest relative error in enlarging the weak signal (100mV) is 1.11%, 24 bits of high-precision A/D conversion module bases onΔ–ΣOversampling technique can make the distinguish ability achieve 19 bit.(2)Adopting ideas of bottom-up to design relevant function module with VHDL language, through controlling the timeshare call function module (input module, points frequency modules, look-up table module, accumulative module) to implement filter algorithm.(3)Realizing Multiple parameters configuration of the filtering systems, through external interface control, allocating filters with different parameters to filter corresponding noises.(4)Completing software level simulation of the filter, realizing the filtering effect.