This paper deals with the assessment of the uncertainty due to systematic errors, particularly in A/D conversion-based instruments. The problem of defining and assessing systematic errors is briefly discussed, and the conceptual scheme of gauge repeatability and reproducibility is adopted. A practical example regarding the evaluation of the uncertainty caused by the systematic offset error is presented. The experimental results, obtained under various ambient conditions, show that modelling the variability of systematic errors is more problematic than suggested by the ISO 5725 norm. Additionally, the paper demonstrates the substantial difference between the type B uncertainty evaluation, obtained via the maximum entropy principle applied to manufacturer’s specifications, and the type A (experimental) uncertainty evaluation, which reflects actually observable reality. Although it is reasonable to assume a uniform distribution of the offset error, experiments demonstrate that the distribution is not centred and that a correction must be applied. In such a context, this work motivates a more pragmatic and experimental approach to uncertainty, with respect to the directions of Supplement 1 of GUM.
|Autori interni:||ATTIVISSIMO, Filippo|
|Titolo:||Assessment of the uncertainty associated with systematic errors in digital instruments: an experimental study on offset errors|
|Rivista:||MEASUREMENT SCIENCE & TECHNOLOGY|
|Data di pubblicazione:||2012|
|Digital Object Identifier (DOI):||10.1088/0957-0233/23/3/035004|
|Appare nelle tipologie:||1.1 Articolo in rivista|