直流共模抑制比的精确测量与校准研究  

Accurate Measurement and Calibration of DC Common Mode Rejection Ratio

作　　者：梁志国[1] 冯秀娟[2] LIANG Zhiguo;FENG Xiujuan(National Key Laboratory of Metrology and Calibration Technology,Changcheng Institute of Metrology and Measurement,Beijing 100095,China;Division of Mechanics and Acoustics Metrology,National Institute of Metrology,Beijing 100029,China)

机构地区：[1]北京长城计量测试技术研究所计量与校准技术重点实验室,北京100095 [2]中国计量科学研究院力学与声学计量科学研究所,北京100029

出　　处：《测控技术》2023年第10期67-73,共7页Measurement & Control Technology

摘　　要：针对数据采集系统的共模抑制比测量精度不高的问题,以波形分析方式研究了直流共模干扰的表现形式,揭示了其同时含有直流偏移叠加交流波动和本底噪声的典型特征。比较了4种不同的直流共模抑制比计算方式的特点,提出以波形幅度绝对值的平均值进行干扰强度表征,并进行直流共模抑制比的定量表述,同时,使用平均值叠加模型对系统本底噪声的影响予以剔除,提高了直流共模抑制比的测量精度。基于该方法与流程,讨论了其主要的不确定度来源——信号源误差、数据采集系统增益误差、幅度测量误差、幅度分辨力误差、测量重复性等。进行了测量不确定度分析和评价;结合一个实例,给出了通道直流共模抑制比的不确定度评价结果,验证了所述方法的实用性与可行性。Aiming at the problem that the measurement accuracy of the common mode rejection ratio(CMRR)of the data acquisition systems(DAS)is not high,the manifestation of DC common mode interference is stud-ied by means of waveform analysis,and the typical characteristics of DC offset superimposed AC fluctuation and background noise are revealed.The characteristics of four different DC CMRR calculation methods are com-pared,and the interference intensity is characterized by the average value of the absolute value of the waveform amplitude,and the DC CMRR is quantitatively expressed.At the same time,the influence of the average super-position model on the system background noise is eliminated,which improves the measurement accuracy of the DC CMRR.Based on this method and process,the main sources of uncertainty,such as signal source error,data acquisition system gain error,amplitude measurement error,amplitude resolution error,and measurement re-peatability,are discussed.The measurement uncertainty is analyzed and evaluated.Combined with an example,the uncertainty evaluation result of channel DC CMRR is given,and the practicability and feasibility of the method is verified.

关 键 词：计量学 不确定度 直流共模抑制比 评价 校准 数据采集系统 

分 类 号：TH701[机械工程—仪器科学与技术]