Subject: EMF-L Tech Microwave base stations Date: Fri, 25 Jul 1997 155843 -0500 (CDT) From: aphilips@gn.apc.org (Alasdair Philips) To: Multiple recipients of list <emf-l@mail.llion.org> -------------------------------------------------- Dear all I continue to develop my thoughts on cell phone base stations and present my latest "ruminations". They were prompted by a Powerwatch member sending me a report giving measurements, made by a reputable firm of consultants, near a 1.8GHz cellphone base station mast at her children's school. The meter they used was a reputable make and was recently recalibrated. An RMS (Root Mean Square) meter is not ideal to measure the pulsed radiation from TDMA (Time Division Multiple Access) communications systems such as the GSM standard. An RMS meter theoretically measures the average power but often is not good at time averaging the short widely spaced pulses from these TDMA systems. Assuming the averaging is done accurately, and only one channel was active at any one time, we need to multiply the field values by a factor of around 8 to estimate peak power during the actual pulses. This would give levels of around 10 volts/metre which is 20 times lower than the current UK NRPB Guidelines, and about 6 times lower than the proposed pan-European CENELEC Pre-ENV 50166-2 levels at this frequency. I use the x8 as I believe the peak power in the pulses is important, however, as both sets of guidelines actually refer to 6 minute averages theoretically we should not use the x8 factor and the "safety" margins become about 160 times and 48 times respectively. In fact the CENELEC standard does include complicated formulae for peak pulse amplitudes, but these are still based on power levels. If fact I do not think it is an issue of power, but of information. Our bodies pick up the pulsing of these signals and this may interfere with complex cellular processes. Assuming the pulses they measured had a magnitude of 10 volts/metre we need to ask how this level compares with the ambient background level. The natural thermal background level at 1.8GHz is somewhere between 20 and 50 microvolts/metre (26dBuV/m and 34dBuV/m). The "man-made electrosmog" level is usually below 100 (40dBuV/m) microvolts/metre, with strong broadcast TV (500MHz) and FM radio (100MHz) signals normal not exceeding 0.1volts/metre (100dBuV/m) unless you are close to a large broadcast transmission mast where they still rarely exceed 2 or 3 volts/metre. If we accept an unusually high "ambient" level of 0.1volts/metre we see that these cell-phone base-station pulses are poking up 100 times higher than this - so, of course, our bodies WILL detect them. It would be like someone flashing a torch or beacon at us. The official agencies say "so what, there is not enough power to be dangerous". Dr Von Klitzing says they change our brainwave patterns, though his work has not been successfully replicated. You pay your money, use your intuition, and in the end have to make your choice. There is no absolute answer - we just do not know yet. If you are not happy, then change your children's school and encourage other parents to do the same. That would at least make the school governors sit up and think. These are just some further thoughts by Alasdair Philips I welcome comments & criticism as it helps my thinking move forward. Alasdair, Powerwatch Network, UK. Alasdair Philips (aphilips@gn.apc.org) Archive provided courtesy of WaveGuide, http://www.wave-guide.org Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html