正弦波相位差的测量不确定度

Measurement uncertainty of sine wave phase difference

本文介绍了用四参数正弦波最小二乘拟合法评价正弦波信号源相位差指标时的不确定度分析和评价过程。通过使用国军标GJB 3756-1999"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,包括采集速率的不确定度、通道间延迟时间差的不确定度、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,给出了相位差测量结果的不确定度的分析与合成过程。结合一个实际评价例子,给出了相位差指标不确定度分析和评价结果,表明了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正弦波相位差指标的不确定度分析上,也可用于估计正弦波相位差指标本身的不确定度。

In this paper, the uncertainty analysis and evaluation process are described, during which the least mean square four-parameter sine wave curve-fit method is used to evaluate the phase difference between two sine wave signal generators. Using the method from the Chinese military standard GJB 3756-1999 ＂Expression and evaluation of uncertainty in measurement＂, some error sources of phase evaluation are discussed, including sampling rate uncertainty, the uncertainty of delay between channels, harmonic distortion of the sampling serials, quantization errors ＆ noise ＆ spurious distortion, the jitter of the signal periods in sampling serials, calculation errors of the software, and so on. The measurement uncertainty of phase difference is given, and several main methods for decreasing the phase evaluation error and phase evaluation uncertainty are proposed . With an experiment example, the uncertainty analysis and evaluation result of phase difference using the proposed method are presented, which validate the correctness and feasibility of the proposed method. The process and conclusion of uncertainty analysis and evaluation of phase difference presented in this paper can be applied to the uncertainty evaluation of phase difference measurement standards, and can also be used in the uncertainty evaluation of sine wave phase difference itself.