A-1
Appendix A
Glossary
adc (analog-to-digital converter)
A device or circuit that changes an analog signal to digital signals.
absolute uncertainty
Uncertainty specifications that include the error contributions made by all equipment and
standards used to calibrate the instrument. Absolute uncertainty is the numbers to
compare with the UUT to verify uncertainty ratio.
accuracy
The degree to which the measured value of a quantity agrees with the correct value of
that quantity. For example, an instrument specified to +1% uncertainty is 99% accurate.
apparent power
The power value that you get when you multiply the ac current by the ac voltage on a
circuit without consideration of phase relationships between the two waveforms. (See
“true power” for comparison.)
assert
To cause a digital signal to go into a logic true condition.
af (audio frequency)
The frequency range of human hearing, typically 15,000 - 20,000 Hz.
artifact standard
An object that makes or embodies a physical quantity to be standardized, for example a
Fluke Calibration 732A DC Voltage Reference Standard.
base units
Units in the SI system that are dimensionally independent. All other units are derived
from base units. The only base unit in electricity is the ampere.
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