岩石电磁辐射信号观测系统构建及检验

Construction and evaluation of a detection system for electro magnetic signals emitted from rocks

针对岩石电磁实验研究需要,构建专用岩石电磁辐射信号观测系统。铜板电容传感器的采用,将观测的频率带宽由固定点频拓宽至2.5 kHz—800 kHz的宽频带范围;PXIe-6368数据采集卡的应用,消除了PAC声发射仪的带通滤波和波形前端滤波功能对信号的影响,使观测系统可以记录到原始的EME信号。通过人工信号和岩石加载实验,对观测系统进行检验,发现:该观测系统可以采集2.5 kHz—800 kHz频带范围内0.1 mV以上EME信号,具有每通道最大2 M采样率、最多16通道同步采集功能。本套电磁辐射信号观测系统可以用来检测岩石加载过程中产生的EME信号,也可用于多种岩石物性参数的多通道同步采集。

An improved observation system is proposed to detect electromagnetic emissions produced by rocks during load compression experiments.It is found that the use of capacitive sensors widens the frequency bandwidth from2.50kHz to800kHz and the PXIe-6368data acquisition card eliminates the effects of band-passing and waveform filtering,allowing the system to record the complete electromagnetic emission.The system is capable to detect signals above0.1mV amplitude with a maximum of2M sampling rate per channel.Because of the multi-channel input,up to16,emissions can be detected simultaneously with various petrophysical parameters.