WiFi in EMF sensitive environments
Can anyone tell me whether WiFi networking is permissible in hospital wards? My local acute hospital insists that everyone turns off their mobile phone one entering, the published explanation being that the signals that phones regularly send to inform the network as to which cell they are in can interfer with monitoring and other equipment. This is the same explanation as given by airlines and may just be precautionary rather than a serious threat to safety.
If it's in the same frequency band, I'd steer clear.
We have some old, old language labs and we play tapes from a tape deck throuigh two wall speakers. If the students have the mobile phones switched on, even though they are not being used, the interference comes through the speakers and makes the tape uniintelligible.
802.11a almost certainly is not interfering with anything, as it's 5GHz. 802.11b and g, on the other hand, live in the rather noisy and crowded 2.4GHz band. Cell phones do not operate in either band, though.
Brad Wilson (dotnetguy.techieswithcats.com)
david, the hospital where I work does have a WiFi network in the wards.
Re: cell phones in airplanes:
You need to work closely with the hospital's biomed department. I've worked on medical equipment before (an EEG monitor called the Neurotrac II). Depending on the equipment, some of it (especially EEG gear) can be VERY sensitive to noise. And radio signals can do all sorts of wierd and unexpected things inside a building, some of which can cause a very high-frequency signal to alias down into very low bands and interfere with things that you wouldn't expect.
I think the cell phone rule on airplanes is an FCC rule, not an FAA rule. It's not designed so much for interference with flight systems, as it is to prevent problems or "free calls" on cellular networks when you're up at 30,000 ft. From there, you're within line-of-site of thousands of cellular towers.
On the hospital issue (which was the original question anyway), I would hope that all electronic hospital equipment is tested to be resistant to any publicly available frequency spectrum. Since WIFI operates in such a frequency theoretically those devices should be OK.
It would be nice if all hospital equipment were relatively immune to RF interference, unfortunately for a lot of things (EEG and heart monitoring at least) you are measuring electrical signals in the patient. To do so, you effectively make the patient part of the circuit. Since humans are (unfortunately) rather good antennas, and grounding is shaky at best in these things, you can't avoid some amount of RF getting into the mix.
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