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Technology Stocks : Qualcomm Moderated Thread - please read rules before posting -- Ignore unavailable to you. Want to Upgrade?

To: Maurice Winn who wrote (15263)	9/27/2001 3:22:01 AM
From: pheilman_	Respond to of 197208

Maurice, 100 milliwatts average, with an 12.5% duty cycle gets the peak power up to 800 milliwatts. Taking your assumptions of 20 watts and a 10% absorption, it is 1/250th of the energy. And since the pulsing is in the audio range, I would not be at all surprised if RF pulsing was audible. Not loud, just audible. It certainly wipes out any other RF system in the vicinity. The ear is a logarithmic system. Tiny movements thru heating of any of the components would be audible. No need to cook the brain for there to be an apparent acoustic effect. Pulsed RF bad, continuous good. Pulsed RF requires temporal guard bands of sufficient duration for the largest cell. And for the ramping up and down of the transmitter. Again, CDMA systems, by design, use the absolute minimum mobile RF power that can be used. I just wish it showed up in longer battery life. Since that is what most customers really care about. Paul

To: Maurice Winn who wrote (15263)	9/27/2001 12:57:25 PM
From: John Walliker	Respond to of 197208

Maurice, Also the thermoelastic pulse from 0.01 watts switching on and off would be undetectable compared with the normal arterial and other pulsing going on in a brain. The basilar membrane which supports the sensory hair cells in the cochlea does not have a blood supply. Instead it is bathed in fluid which carries nutrients and oxygen. This minimises the detection of the sound of pulsatile blood flow. I don't believe anyone can hear a cellphone [via thermoelastic pulse due to brain heating]. That should be really, really easy to test. There wouldn't even be a need to do large studies. Just get twenty 17 year old women [whose ears are still really good and who can hear 20 kilohertz ... The pulsing of GSM signals is at 217 Hz, so anyone with reasonable hearing should be able to hear this effect if it were significant. Just to complicate things, the mechanism by which high-level pulsed electromagnetic fields is heard is not clear-cut. Another possible mechanism is that bone is piezo-electric and changes shape in the presence of an electric field. Cell membranes respond non-linearly to high frequency fields and can demodulate their envelope which might then drive the piezo-electric sound generation mechanism. John