被动源电磁数据采集系统的设计与开发

【作者】 孙娴；

【导师】 罗桂娥；

【作者基本信息】 中南大学 ， 电路与系统， 2008， 硕士

【摘要】 目前被动源电磁法已成为深部地球物理勘探的重要手段,在油气田勘测和地热等方面得到广泛应用。但国内相关仪器几乎全部依赖进口,成本极高,所以为自行研制一套被动源电磁法仪器,本文对被动源电磁数据采集系统进行了研究。本文在研究被动源电磁法采集原理的基础上,结合我国电磁法勘探的特点,提出了满足电磁采集要求的系统软硬件设计方案。选用DSP+ARM的双核系统结构,来分别完成实时抽取滤波运算和对系统的主控制,提高了系统整体的稳定性和工作效率。并从模拟信号采集通道设计、系统控制处理模块与功能辅助模块实现、多级抽取结构算法研究等方面对被动源电磁采集系统进行了重点研究。针对电磁采集易受到工频干扰的问题,设计了基于UAF42的两级陷波电路。对于低频段电磁场频率范围宽、信号微弱的特点,采用大动态范围、高精度的24位△-∑调制器CS5321来实现模数转换。并基于DSP56309的硬件结构,对电磁采集中用到的多级抽取滤波结构算法进行了研究,提出了符合电磁采集要求的多级抽取滤波的实现方案。系统的联机测试结果表明,本文所开发的电磁采集系统性能稳定,15Hz抽样率数据的短路输入噪音很小,在低频电磁采集方面具有一定的实用价值。更多还原

【Abstract】 Passive source electromagnetic method has become the main way of the geophysical technology in deep exploration for now, and it was generally used in oil gas survey, geothermal and so on. However, almost all of the electromagnetic instruments used at home were imported from the abroad and cost high. Therefor this paper research on the Passive source electromagnetic data acquisition system to study and develop an electromagnetic acquisition instrument.On the basis of passive source electromagnetic method data acquisition principle and combined with the electromagnetic exploration actual conditions in our country, this paper give a soft hardware design system plan which can meet the electromagnetic acquisition requirements. Use the DSP+ARM dual-core system architecture to accomplish mass realtime calculation and the system master control separately, and enhance the system stability and efficiency. This paper emphasis on research of passive source electromagnetic data acquisition system in the aspects of analog signal acquisition channel design, system control process module and auxiliary function module realization, and the multi-stage decimation filter architecture algorism research. Aim at the problem that the electromagnetic acquisition are liable to the interference on the specific frequency, this paper use the universal active filter chip UAF42 to compose two-step notch filter circuit. For the low frequency section of electromagnetic field has weak signal and wide frequency band, use high resolution and large dynamic range 24-bit△-∑modulator CS5321 to realize the analog digital conversion. On the basic of the hardware architecture of DSP56309, this paper emphasis on the research of the multi-stage decimation filter architecture algorism which used in electromagnetic acquisition and give an implement method.The experiment results show that the passive source electromagnetic data acquisition system has steady state performance and very low short circuit input noise in the 15Hz sample rate data aspect, so it has the practical value in some manner.更多还原