Measurement Uncertainty and Traceability of PC-Based Data Acquisition Systems

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Measurement Uncertainty and Traceability of PC-Based Data Acquisition Systems (1.35 MB)

Calibration and measurement uncertainty problems are often associated with PC-based data acquisition equipment both PC plug-in boards and external front-end chassis. Often with PCbased instrumentation systems, the measurement hardware is calibrated with one PC, then moved back to its “host” PC for actual operation. For the plug-in card, this procedure creates a situation where traceability cannot be reliably maintained due to the uncharacterized condition (inside the host PC) in which the measurements are made. A case can further be made that even if the measurement hardware is calibrated while situated in its host PC, noise conditions experienced during actual operation will not be the same as those experienced during its calibration simply because different software is running on the computer, changing the ways in which the memory and video hardware are used. This again poses the problem of measurement uncertainty that may only ultimately be solved through utilizing measurement devices external to the PC posessing known and controlled measurement environments. Ultimately, it is up to the user to decide how important these issues are in his application.