Measurement Uncertainty & Calibration Flashcards
6 cards from real FCC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Measurement Uncertainty & Calibration flashcards as text
What does 'measurement uncertainty' mean in FCC laboratory testing?
Answer: A parameter that characterizes the dispersion of values that could reasonably be attributed to the measurand
Measurement uncertainty is a quantified estimate of the range of values within which the true value of the measurand lies, taking into account all recognized sources of error in the measurement process.
What international document provides guidance on evaluating and expressing measurement uncertainty?
Answer: GUM (Guide to the Expression of Uncertainty in Measurement)
The GUM, published by BIPM and co-sponsored by multiple international organizations, is the internationally accepted method for evaluating and expressing measurement uncertainty.
In uncertainty analysis, what is the difference between Type A and Type B evaluation?
Answer: Type A uses statistical analysis of repeated measurements; Type B uses other means such as calibration data or expert judgment
Type A uncertainty evaluation uses statistical methods on a series of repeated observations, while Type B evaluation uses information from calibration certificates, manufacturer specifications, or scientific judgment.
What is the 'expanded uncertainty' reported on a calibration certificate?
Answer: The combined standard uncertainty multiplied by a coverage factor k, typically k=2 for approximately 95% confidence
Expanded uncertainty U = k × uc, where uc is the combined standard uncertainty and k is the coverage factor (typically k=2), providing an interval with approximately 95% confidence level for a normal distribution.
Why is it important for FCC laboratories to account for measurement uncertainty when comparing results to emission limits?
Answer: Because a measurement result plus its uncertainty that exceeds the limit indicates the device may not comply even if the nominal reading is below the limit
When a test result is near the emission limit, the measurement uncertainty indicates whether the true value could exceed the limit, which is critical for making correct compliance decisions.
What is 'calibration traceability' and why is it required for FCC test equipment?
Answer: An unbroken chain of comparisons linking measurement results to national or international standards, ensuring measurement accuracy
Traceability means each calibration in the chain can be traced back to a recognized measurement standard (such as NIST in the US), ensuring that FCC test results are comparable and defensible.