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FEMA To Use Cell Phone Signals To Find Survivors
twistah writes: "CNN had an interview with a representative of the Federal Emergency Management Agency (FEMA), the agency helping with the New York WTC rescue effort, who said that Lucent has given them technology to trace the signal of cell phones. The idea is that people will give them phone numbers of cell phones and pagers of people missing due to the WTC collapse, which FEMA will call and attempt to trace the signal to find the missing people. FEMA has now put this information on their web site, and are dubbing it the 'Wireless Emergency Response Team.'"
While you're almost certainly correct about phones, my two-way pager's battery lasts for at least a month, so there's at least that.
The company I work for is doing the same thing. They haven't done it already because it's never been done before. With CDMA phones it's not as simple as looking for a specific frequency, they have to identify the phone by the code it uses to decode the signal.
People I work with have been working very hard to modify the basestation software to allow them to search for a particular phone. They are basically strapping a small base station to their back and walking around the rubble.
Yes, there is a shopping mall below the WTC complex, as well as a PATH station and a NYC Subway station. I haven't heard anything on the news about how it held up under the weight of the collapse. It would seem that if it did hold, rescue workers could approach the site from below via the train tubes.
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They're trying to clear the subway tunnel under the building to see if anyone actually on the platform under the towers survived. The problem is that water mains have burst, flooding the tunnels and filling them with debris. At present I think they're a third of the way there.
There are multiple ways to locate a cell phone or pager, and I suspect they will use all of them. Some have already mentioned GPS, that's rare to non-existant in today's devices. More likely are triangulation, or simple signal strength.
Several cell providers have been using triangulation to work towards the E911 requirements. Rather than implement expensive GPS solutions, they simply track a phone from multiple antennas, and triangulate the location of the phone from that. While normal accuracy is only +- a quarter mile, in an instance like this local portable cells could bet set up around the site and generate high accuracy.
Even if that can't be done, making a cell phone talk to the cell site (telling it to reregister, for instance) would allow you to listen for its signal with a strength meter. Walk away it reduces, walk towards it gets stronger. In a relatively small area like this it would work well.
Of course, there is also low tech. If they ring the phones, and make the area quiet, they can hear them ring. For those very near the surface this could be particularly effective.
Others have commented on batteries. Many cell phones are probably running low, but I would venture about 1/3 of today's phones last a week on standby, and would still be able to ring. Two way pagers and other communications devices often last longer, two weeks or more at a go. They could still have a huge number of these devices active. That said, they need to be careful. Ringing them too much will run out batteries.
I wish them luck, it's a good idea.
Well, the microwave oven certainly does shield users from the microwave emissions. But it's not terribly effective outside a certain frequency range.
The actual cooking area is tuned to the microwave frequency in use - around 2.45GHz. If you operate a microwave with the door open, it won't do you a lot of good, but the radiation *away from the direct "beam" of microwaves* is incredibly weak.
Now, mobile phones (UK GSM, but others are similar) tend to work around 900MHz for low band, and 1800MHz for high band. It's not really near the resonant frequency of the cooking chamber, so doesn't get absorbed (can you say "Helmholz bottle"?)
Finally, this is also why mobile phone cell towers are *not* dangerous - a microwave oven uses a very specific frequency, at very high power, from a distance of *inches* to cook food. A cell tower uses a lower frequency, with very low power (often as little as 10w), from much further away...