M. Alex Johnson – Journalist at Large

An analog journalist in a digital world

Posts Tagged ‘gps

E911: Needle, meet haystack

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Exactly two years ago tomorrow, I wrote an msnbc.com piece about the accuracy of 911 calls from wireless phones. The takeaway was:

[T]he accuracy of location data generally drops in rural areas, where older, less-advanced cell towers can be farther apart, the Congressional Research Service found in a background report for lawmakers late last year. And it can drop in densely populated cities, where a phone might show up as being at 1 Main St., with no indication of whether it’s on the seventh or the 77th floor.

Depending on the technology a carrier is using — GPS or tower triangulation — FCC regulations allow a margin of error of up to 300 meters for some E911-capable phones. That’s longer than three football fields.

Today, the Federal Communications Commission published proposed E911 regulations that wouldn’t allow carriers to rely on tower triangulation — that is, measuring a phone’s distances from its three closest towers, which is the measure that yields the 300-meter margin of error. Instead, carriers would have to use location services on the device itself (GPS, for example), which is supposed to be accurate within 50 to 150 meters.

It would take Usain Bolt almost 15 seconds to sprint 150 meters — assuming stairs weren’t involved. Not all GPS services measure or report altitude, so they can’t indicate which floor you’re on if you’re in a high-rise building.

The technology to make wireless E911 work is incredibly difficult, but the new regulations mean that even under optimum conditions,  you could still be waiting a good amount of time for emergency crews to find you.

That’s the first caution. The second is that the new regulations wouldn’t take effect until after an eight-year sunset period; the current three-football-field allowance would be OK until 2019.

What do you think? Is that close enough? Do you expect better technology to be created in the near future? And if it is, what would the implications be for individual privacy?

Written by Alex

July 12, 2011 at 3:43 pm

Posted in Tech

Tagged with , , , ,

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