8.9.2 Measurement Configuration And Settings
Instrument settings must match the signal and the required measurand. Relevant settings can include frequency span, resolution bandwidth, detector type, sweep or acquisition time, trigger, sample rate, dwell time, averaging mode, range, axis combination, and software correction factors. Settings should be selected before the survey where possible and retained with the measurement record.
A calibrated antenna system requires the correct antenna factor, cable loss, preamplifier gain, impedance, and polarization. A single-axis sensor must be oriented or measured in orthogonal directions as required to obtain the resultant field. Isotropic probes reduce orientation sensitivity but retain finite isotropy error. Cables, adapters, and connectors must be appropriate for the frequency and included in the system corrections and uncertainty.
8.9.3 Temporal Sampling And Averaging
The sampling interval and observation period must represent both the temporal behavior of the source and the averaging or integrating conditions of the applicable exposure standard. Under RPS S-1, sustained whole-body quantities are averaged over 30 minutes, sustained localized quantities over 6 minutes, and brief localized exposure above 400 MHz is subject to additional energy-based restrictions for every applicable interval greater than zero and shorter than 6 minutes. The assessor must distinguish cycle-based RMS measurement, peak or short-duration measurement, time averaging of squared field strength or power density, and integration of energy over a specified interval. Arithmetic averaging of displayed field-strength readings is not generally equivalent to averaging the underlying squared quantity.
The compliance interval is not necessarily the required instrument observation time. AS/NZS 2772.2 permits time averaging through an instrument function or appropriate post-processing and allows duty cycle, modulation, antenna scanning, traffic loading, and known source-power variation to be taken into account. A shorter screening measurement may be used only where the applicable method, operating information, available compliance margin, and any required extrapolation provide a valid estimate of the relevant averaged or integrated quantity. Variable, intermittent, pulsed, scanning, or beam-steered sources may instead require longer observation, repeated measurements, triggered acquisition, or assessment under defined worst-case operating conditions.
Maximum-hold functions should be interpreted cautiously. For frequency-hopping, scanning, or otherwise non-simultaneous signals, maximum hold can retain maxima from different times or frequencies and thereby imply a combination that never occurred. It may be useful for conservative screening or locating peaks, but its relationship to the required exposure quantity must be justified.