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

The probability that a device will fail FCC testing

Answer

The error introduced by a poorly calibrated antenna

Answer

The difference between two consecutive measurements

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

ISO 9001

Answer

ANSI C63.4

Answer

FCC Part 15

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 covers random errors; Type B covers only systematic errors

Answer

Type A applies only to antenna measurements; Type B applies to conducted measurements

Answer

Type A is required by FCC; Type B is optional

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

The maximum possible error in a measurement

Answer

The uncertainty due to random effects only

Answer

The uncertainty introduced by the calibration laboratory's environment

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

Because FCC rules require laboratories to add uncertainty to every result before reporting

Answer

Because measurement uncertainty determines the pass/fail threshold automatically

Answer

Because uncertainty must be subtracted from the limit to determine the test margin

Question 6

What is 'calibration traceability' and why is it required for FCC test equipment?

Accepted Answer

An unbroken chain of comparisons linking measurement results to national or international standards, ensuring measurement accuracy

Answer

A record of who calibrated the equipment and when

Answer

The requirement that all calibrations be performed by an ISO/IEC 17025 accredited laboratory

Answer

The process of verifying that equipment passes self-diagnostic tests