Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Do piano tuners perceive a wifi shut down ?

A friend of mine who owns a gauss meter figured out pretty conclusively that the refrigerator/freezer, clothes dryer, and nearby high voltage power lines are the most significant sources of e/m fields in a domestic setting.

I sleep with an aluminum foil (erroneously called tin foil) hat on. It makes my head sweat and itch a bit, but it protects me from my refrigerator EM, and the government can't read my mind or mess with my dreams.

I always used to get a kick out of the story one of the grey beards at my co-op used to tell about doing field testing of a microwave antenna system on an aircraft carrier in the North Atlantic. Apparently several times a day they'd have to go up and shoo the seamen on watch away from the antenna, because they had discovered if they stood right in the focal point it was nice and warm

Rob

There are studies suggesting dangerous effects of EM fields, in spite of absence of good physical explanations for it.

For example, living near power lines

http://news.bbc.co.uk/2/hi/health/4602315.stm

It's hard to believe this is all due to a placebo effect.

There is some evidence that there might be long term risks from using cell phones

http://en.wikipedia.org/wiki/Mobile_phone_radiation_and_health

First off....a cell phone transmits about anywhere between .5 and 1 watt of power, which is negligible. My handheld ham radio transceiver puts out 5 watts, which is nearly a 7 dB increase in power over a cell phone. There really is no conclusive evidence linking cell phone radiation to health hazards. There is a lot of FEAR (False Evidence Appearing Real), and the news media seems to love picking up on it.

Second....people hear the word "radiation" and freak out, thinking of ionizing radiation (like a nuclear plant). The only thing RF can do is heat tissue in strong enough amounts (think about your microwave oven), but that is at microwave frequencies and at very high wattages (my microwave oven operates at 1300 watts. I do steer clear of it when it's operating).

And third, Wikipedia. Not a reliable source of information, but that's a whole other thread!

Well that's a tricky one, and as this thread demonstrates a pretty polarizing issue. Lots of people like to worry about it, and lots of people like to make fun of those who worry about it. IMHO the reality is, like many of the things we are introducing into our daily environment we really have no idea what the long term health effects are.

FWIW I happen to be an EE with a background in microwave communications and radar systems, though I've been in fiber-optic microelectronics for the past ~10 years. That's not to say I pretend to be any sort of an expert on the health effects of EM radiation, I just know enough to realize that most of the arguments presented on the topic don't make much sense.

A couple of somewhat important points that are usually glossed over:

- The energy conveyed by an EM wave is directly proportional to its frequency. So for the same power level, a cell phone or wifi signal operating in a GHz band has about 10-1000 times more energy than TV/Radio signals. As mentioned motors/compressors etc in household appliance can create substantial amounts of EM radiation, but at 60Hz, these have about 83 million times less energy per watt than a 5GHz wifi signal.

- The power density of a transmitted EM wave typically decreases with the square of the distance from the source. So your own wifi base station 10' away is effectively about 1000 times more powerful than your neighbor's 300' away. Similarly a 50W cellphone base station a mile away produces about 1/15th the local power density of an 0.125W cell phone 1' away.

Combining these two points, the absorbed energy from a 50,000W 100MHz FM transmitter 5 miles away is roughly 1/300,000 that of an 0.125W 2GHz cell phone 1' foot away.

The power level of a wifi router is rather small compared to a cell phone, about 0.028W vs. 0.125W. It can be up to 2X in frequency, but energy is still lower and its usually not as close as your cellphone. However, your cellphone power is intermittent, it varies depending on signal strength (more power when weaker) and just checks in on the network periodically at low power unless in active use. Wifi is typically on all the time.

Does it concern me? Yes. Does their seem to be any solid evidence its harmful? No. Is it feasible that long term exposure to close sources of high frequency EM radiation could have long term effects on health or behavior? Probably. Have the studies been done to show beyond a reasonable doubt that they don't? No. Will they ever? Doubtful. Proving long term effects on large populations at low dosage is extremely difficult, and given how much money there is to be made on wireless technologies there is not much incentive.

FWIW I have wifi, use a cellphone, and only hide in our Faraday cage here at work occasionally

On the other hand, why not turn off your wifi and anything else you don't need at night? It may or may not make any difference, but you might as well save a little electricity

Rob

The energy conveyed by an EM wave is directly proportional to its frequency.

So for the same power level, a cell phone or wifi signal operating in a GHz band has about 10-1000 times more energy than TV/Radio signals.

That's only part of the story.

....For the same amplitude, a higher frequency has more energy (or power). But for the same power level, as you have stated, energy (per unit time) is the same for both waves: P = E/t, i.e. E = P*t.

A 1 W wave carries 1 J/s, irrespective of the frequency. So, the energy (per time) in a 1 W microwave signal is the same as in a 1 W radio signal: 1 J/s. Their amplitudes, however, are vastly different.