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. 2019 Dec 31;187(2):191-214.
doi: 10.1093/rpd/ncz154.

APPLICATION OF TIME-AVERAGED AND INTEGRAL-BASED MEASURE FOR MEASUREMENT RESULTS VARIABILITY REDUCTION IN GSM/DCS/UMTS SYSTEMS

Darko Šuka  1 , Predrag Pejović  2 , Mirjana Simić-Pejović  2
Affiliations

APPLICATION OF TIME-AVERAGED AND INTEGRAL-BASED MEASURE FOR MEASUREMENT RESULTS VARIABILITY REDUCTION IN GSM/DCS/UMTS SYSTEMS

Darko Šuka et al. Radiat Prot Dosimetry. .

Abstract

Since EMF levels from wireless telecommunication networks are non-stationary and exhibit large temporal variations, the use of continuous measurements during extended periods (preferably 24 h or longer) with a data-logging system is required. Because of the short-term variations of E field, the 6-min measurements and 6-min averaged results to obtain the mean level strength at a given place appear to be dependent on the time of measurements during the day. This paper presents a new (integral-based) measure to evaluate electromagnetic exposure. The new measure is a pure physical descriptor of the amount of exposed energy density (a parameter accumulated from instantaneous power density values in time). To confirm previous observations, continuous measurements with personal exposure metre were recorded 24 h a day for two weeks at every location in urban area, 14 different locations in total. Additionally, to check temporal variations and repeatability of exposure assessment, a week of prolonged measurements was taken 6 months later, making in total three weeks of measurements at 2 locations. Day-to-day repeatability of RF-EMF exposure was analysed through the time-averaged and integral-based measure. The analysis is based on approximately 5.1 million data samples (1.7 million for each band). The ratio between the maximum and minimum instantaneous (maximum and minimum 6-min averaged) E field values during the day could reach up to 25 dB (20 dB). Therefore, great variability in the results may occur. By applying the 24 h time-averaged and integral-based measure on a 24 h data set of measurements, the variability of daily exposure could stay within ±20% of the week mean level obtained either with the time-averaged or integral-based measure. Both, the time-averaged E field and integral-based power density exposures of the general public in all locations were found to be well below the general public exposure limits of the ICNIRP guidelines.

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Figures

Figure 1.
Figure 1.
Temporal variations of E field strength for GSM downlink band over the first week.
Figure 2.
Figure 2.
Probability density functions (PDFs) of the instantaneous E field for GSM downlink band for days of the first week.
Figure 3.
Figure 3.
Cumulative distribution functions (CDFs) of the instantaneous E field for GSM downlink band for days of the first week.
Figure 4.
Figure 4.
Time-averaged E field strength for GSM downlink band with variable averaging time (10 s to 24 h, time-step: 10 s) over the first week.
Figure 5.
Figure 5.
Time-averaged relative standard deviation for GSM downlink band with variable averaging time (10 s to 24 h, time-step: 10 s) over the first week.
Figure 6.
Figure 6.
Integral-based (cumulative) measure of instantaneous power density values for GSM downlink band over the first week.
Figure 7.
Figure 7.
Exposed energy density normalised to first week mean level of exposed energy density (W24hmean_week) for GSM downlink band.
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References

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