基于斩波技术的长周期大地电磁接收系统  

Research on Long Period Magnetotelluric Receiving System Based on Chopping Technology

作　　者：周炀[1] 周逢道[1] 王绪磊 ZHOU Yang;ZHOU Fengdao;WANG Xulei(College of Instrumentation and Electrical Engineering,Jilin University,Changchun 130026,China)

机构地区：[1]吉林大学仪器科学与电气工程学院,长春130026

出　　处：《实验室研究与探索》2020年第8期83-86,100,共5页Research and Exploration In Laboratory

基　　金：国家潜在油气资源产学研用合作创新项目(OSR-02)。

摘　　要：低频噪声的存在对长周期大地电磁接收系统的性能有着较大影响。为提高信噪比和分辨率,研制一种基于斩波技术的低噪声长周期大地电磁采集系统。采集系统由前置模拟信号调理电路、模数转换电路、液晶显示电路、数据存储电路以及控制电路组成。测试结果表明,在输入信号峰峰值为1 V的情况下,系统各通道间测量差异在微伏级,具有良好的通道一致性;在采样率为12.5 Hz,采集时长为10 000 s情况下,采集电路短路噪声峰峰值在6μV左右,直流漂移优于1μV,无明显直流偏移。The low-frequency noise has a large influence on the performance of the long period MT acquisition system.In order to improve the SNR and resolution,a low-noise long period MT acquisition system based on chopping technique has been developed. The acquisition system consists of pre analog processing circuit,analog to digital converter circuit,LCD,data storage circuit and control circuit. The test results showed that when the peak-to-peak value of the input signal is 1 V,the measure differences among each channel are in microvolt level. The acquisition system has a good channel consistency. When the sampling rate is 12. 5 Hz and the acquisition time is 10 000 s,the peak-to-peak value of short-circuit noise of the acquisition circuit is about 6 μV,the DC drift is less than 1 μV and there is no obvious DC offset in the noise. As shown in the results of field test for comparison,the detection results of the system are coincided with the similar foreign instruments and it meets the requirements of long period MT detection.

关 键 词：大地电磁测深 1/f噪声 斩波技术 数据采集 

分 类 号：P631[天文地球—地质矿产勘探]