宽带岩矿石标本频谱激电测试仪采集系统研制  

Development of the acquisition system of a broadband spectral induced polarization testers for rock and ore samples

作　　者：王飞飞 陈儒军[1,2,3,4] 李生杰 申瑞杰 殷昊[1,2] 刘峰海 彭鑫 WANG Fei-Fei;CHEN Ru-Jun;LI Sheng-Jie;SHEN Rui-Jie;YIN Hao;LIU Feng-Hai;PENG Xin(School of Geosciences and Info-physics,Central South University,Changsha 410083,China;AIoT Innovation and Entrepreneurship Education Center for Geology and Geophysics,Central South University,Changsha 410083,China;Hunan Key Laboratory of Nonferrous Resources and Geological Disaster Exploration,Changsha,410083,China;Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring,Ministry of Education,Changsha 410083,China)

机构地区：[1]中南大学地球科学与信息物理学院,湖南长沙410083 [2]中南大学AIoT(人工智能物联网)与地质地球物理创新创业教育中心,湖南长沙410083 [3]有色资源与地质灾害探查湖南省重点实验室,湖南长沙410083 [4]有色金属成矿预测与地质环境检测教育部重点实验室,湖南长沙410083

出　　处：《物探与化探》2022年第6期1454-1462,共9页Geophysical and Geochemical Exploration

基　　金：国家自然科学基金基础中心项目(72088101)。

摘　　要：采集系统对于岩矿石标本频谱激电测试仪来说至关重要,其性能好坏直接决定了仪器的精度、功耗、采样率、信噪比等,因此,设计出高输入阻抗、高采样率、高精度、低噪音、低功耗的采集系统是整个仪器研制的重点和难点。本文依据四极法测量原理,针对宽频带岩矿石标本频谱激电测试,设计出一款集成了4个采集通道的采集系统。采集系统采用24位ADC芯片AD7760实现A/D转换,采用AD9837芯片产生正弦波形,实现仪器自检,使用型号为XC6SLX25的FPGA芯片实现对采集系统的控制。系统测试结果表明,本采集系统的输入阻抗大于1 TΩ,实现了0.4%的测量精度,最高2.5 MHz的采样速率,1 Hz~200 kHz的仪器带宽,各采样通道短路噪声均低于1 mV,支持1/5/25/125倍可调增益,信号源支持恒压恒流模式切换,恒压有1 mV、10 mV、100 mV、1 V、10 V共5档可选,恒流有1μA、10μA、100μA、1 mA、10 mA共5档可选。本研究开发的硬件系统可以满足岩矿石标本宽频带频谱激电测试需要。The acquisition system is a very important part of a broadband spectral induced polarization(SIP)tester for rock and ore samples.Its performance directly determines the precision,power consumption,sampling rate,and signal-to-noise ratio of the tester.Therefore,it is a focus and challenge throughout the development of a tester to design an acquisition system with high input impedance,a high sampling rate,high precision,low noise,and low power consumption.Based on the principle of the quadrupole method,this study designed an acquisition system of a SIP tester that integrates four acquisition channels.The acquisition system uses the 24-bit ADC chip AD7760 to realize A/D conversion,uses the AD9837 chip to generate sine waveforms for self-check of the tester,and uses the FPGA chip of the model XC6SLX25 to control the acquisition system.The test results of the system are as follow.The acquisition system has input impedance greater than 1 TΩ,survey precision of 0.4%,a sampling rate of up to 2.5 MHz,and a bandwidth of 1~200 kHz.Each sampling channel of the acquisition system has short-circuit noise less than 1 mV and supports 1/5/25/125 times adjustable gain.The voltage and current of the signal source can be switched among 1 mV,10 mV,100 mV,1 V,and 10 V and 1μA,10μA,100μA,1 mA,and 10 mA,respectively.The hardware acquisition system developed in this study can meet the needs for broadband SIP tests of rock and ore samples.

关 键 词：采集系统 频谱激电法 高采样率 低噪音 高精度 

分 类 号：P631[天文地球—地质矿产勘探]