直流偏移的测量不确定度

The Measurement Uncertainty of Direct Current Offset

介绍了用4参数正弦波最小二乘拟合法评价线性测量系统直流偏移指标时,测量不确定度分析和评价过程.通过使用国军标GJB3756-1999'测量不确定度的表述及评定'中推荐的方法,讨论了影响评价结果不确定度的几个主要误差来源,包括信号源误差、采集序列的谐波失真、采集序列的噪声及非谐波失真、采集序列中信号周期的抖动、软件拟合运算误差的影响等,给出了直流偏移的测量不确定度及减小直流偏移指标评价不确定度的主要措施.在一个实际评价例子上,给出了直流偏移指标不确定度评价结果,表明该过程的正确性和切实可行性.该过程及结论可应用在对于计量标准进行直流偏移指标的不确定度分析上,也可用于估计直流偏移指标本身的不确定度.

In this paper, it is described that the uncertainty of evaluation results of Offset of linear measurement system by using the least mean square four-parameter sine wave curve-fit method, including the courses of analysis and evaluation of uncertainty. By using the method from the Chinese military standard GJB 3756-1999 'expression and evaluation of uncertainty in measurement', some error sources of Offset evaluation are discussed, including the signal amplitude errors, the harmonic distortion of sampling serials, the quantization errors and noise and the spurious distortion, the jitter of the signal periods in sampling serials, the calculation errors of software, and the others. The uncertainty of offset of linear measurement systems is given, and several main methods about decreasing the offset evaluation errors and evaluation uncertainty are proposed. In an example of experiment, the analysis and uncertainty evaluation results of Offset by using the method in this paper are presented. The validation of the uncertainty shows the correctness and rightness of the method. The courses and conclusion of analysis and uncertainty evaluation of offset in this paper, can be applied to the uncertainty evaluation of measurement standards of Offset and the uncertainty evaluation of offset itself.