Explanation of Graph
There are 4 frequency bands recorded every day by each monitor. Three of these bands are the mobile phone base station frequency bands and the fourth is an overview of the total field strength resulting from all frequencies from 100kHz to 3GHz.
The International Comission for Non-Ionising Radiation Protection (ICNIRP) have defined different general public guideline limits for different frequencies.
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| Frequency |
ICNIRP General Public Guideline Limit |
| 950 MHz |
4.5 W/m2 |
| 1850 MHz |
9 W/m2 |
| 2150 MHz |
10 W/m2 |
| 100kHz to 3GHz |
2 W/m2 (see note 1) |
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Note 1: As this frequency range is so wide it includes all common radio sources of electromagnetic fields. Some of these are broadcast radio, broadcast TV, emergency services, etc. Therefore the lowest ICNIRP limit is used here as we can’t know the frequencies causing the electromagnetic fields at the location of the monitor
The various areas of the graph webpage are explained below.
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Fig 1. Typical Website Graph Page (950 MHz)
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Just above the graph, the highest field strength recorded by on this graph is shown. In this case it is 0.41V/m which is equal to 0.000446W/m2.
To the left of the graph (on the y-axis) the ICNIRP guideline limit relevant to the band on the graph is shown. In this case the graph is of the field strength resulting from transmissions around 950MHz so the limit is 4.5 W/m2. This level is also shown by the green line on the graph.
The numbers below the guideline limit show the number of times the measured field strength is below the guideline limit.
The measured field strength is shown by the blue line on the graph and the time of day is shown on the bottom of the graph.
Two points have been selected to show how to read the graph, these are points A and B on the graph.
Point A: The time on the bottom of the graph is 04:00 which is 4 A.M. and the field strength is between 300,000 and 400,000 times below the ICNIRP limit of 4.5 W/m2.
Point B: The time on the bottom of the graph is approximately half way between 14:00 and 16:00 (2 and 4 P.M.) i.e. 3 P.M. and the field strength is 20,000 times below the ICNIRP limit of 4.5 W/m2.
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