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State Enterprise “Ukrmetrteststandard”
Інститут електромагнітних вимірювань Державного підприємства «Укрметртестстандарт», Київ, Україна

Measurement of time intervals with low accuracy on intervals from a few seconds to several hours or days is relevant for some broad applications in various fields of activity. Such measurements are widely used in the technological processes of various enterprises during the preparation and quality control of the preparation of medicines, during the maintenance of technical equipment and mechanisms, chemical technological processes, etc. For such measurements, manual electronic quartz stopwatches are widely used, which, despite their not too high measurement accuracy, must guarantee users the accuracy of measurements within the tolerance established by the technical documentation, since the risks of using untested measuring equipment are quite high, or generally unacceptable especially in the medical field. The issue of calibrating quartz electronic stopwatches by various methods remains relevant for many of their applications. The article discusses the calibration of quartz electronic stopwatches by the method of comparison using a digital camera. A calibration scheme for stopwatches was developed and a calibration measurement model was created based on the developed calibration scheme. The contribution of each component of the measurement model to the calibration result and the corresponding uncertainties of the model components were determined. The measurement uncertainty budget was made based on the proposed stopwatch calibration model. The influence of the most significant influential values on the accuracy of measurement results was analyzed. The content of quantitative and qualitative correction indicators, which must be taken into account during calibration to achieve the highest accuracy of measurements, is revealed. The method of calibrating stopwatches described in the article can be used in calibration laboratories that have the appropriate equipment and standards.

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