FCC Measurement Uncertainty & Calibration

Question 1

What does 'measurement uncertainty' mean in FCC laboratory testing?

Accepted Answer

A parameter that characterizes the dispersion of values that could reasonably be attributed to the measurand

Answer

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.

Question 2

What international document provides guidance on evaluating and expressing measurement uncertainty?

Accepted Answer

GUM (Guide to the Expression of Uncertainty in Measurement)

Answer

The GUM, published by BIPM and co-sponsored by multiple international organizations, is the internationally accepted method for evaluating and expressing measurement uncertainty.

Question 3

In uncertainty analysis, what is the difference between Type A and Type B evaluation?

Accepted Answer

Type A uses statistical analysis of repeated measurements; Type B uses other means such as calibration data or expert judgment

Answer

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.

Question 4

What is the 'expanded uncertainty' reported on a calibration certificate?

Accepted Answer

The combined standard uncertainty multiplied by a coverage factor k, typically k=2 for approximately 95% confidence

Answer

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.

Question 5

Why is it important for FCC laboratories to account for measurement uncertainty when comparing results to emission limits?

Accepted 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

Answer

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.

FCC - Federal Communications Commission Certified Laboratory Practice Test

FCC - Federal Communications Commission Certified Laboratory Practice Test

FCC Measurement Uncertainty & Calibration