9.5.5 Post-Processing And Multiple Sources
A field reading or calculated value is not necessarily the final compliance result. Post-processing may include spatial and temporal averaging, interpolation, extrapolation to maximum or representative operating conditions, correction for duty factor or modulation, treatment of uncertainty, and summation of contributions from several frequencies.
The field region governs how external quantities may be interpreted. Far-field relationships may support conversion among electric field, magnetic field, and power density, but they must not be assumed in the radiating or reactive near field. In near-field situations, electric and magnetic fields may need to be evaluated separately, and some cases require assessment against a basic restriction.
Spatial averaging, limits on spatial peaks, temporal averaging, and multiple-frequency summation are compliance rules as well as mathematical operations. The procedures and factors used must be documented, and the rules in the currently governing exposure standard take precedence over legacy examples in AS/NZS 2772.2.
9.5.6 Calibration, Validation, And Uncertainty
Measurement equipment that can materially affect the result must be fit for purpose and supported by valid, traceable calibration from an appropriately accredited laboratory. Calibration intervals must be suitable for the instrument and its use, and the assessor should perform reproducible checks before and after surveys. Damage, drift, or abnormal operating conditions require additional checking or recalibration.
Computational tools must likewise be fit for purpose and validated for the relevant frequency, field region, geometry, and output quantity. Validation may use comparison with measurements, independent numerical methods, analytical solutions, energy or reciprocity checks, convergence tests, and sensitivity to input changes. Software should be reverified after installation on another computer or other material changes to its operating environment.
Every reported measured or calculated RF assessment must include an estimate of uncertainty. The standard describes coverage intervals for environmental and compliance assessments and supplies a default decision-rule approach where the client or regulator has not specified one. The applicable regulator and exposure standard must nevertheless be checked before applying that approach.
Results should be expressed as the best estimate after correction for known systematic effects, accompanied by the uncertainty and the conditions to which the result applies. Uncertainty is not an optional disclaimer; it affects the confidence with which compliance or non-compliance can be concluded, particularly when the result is close to a limit.