geolocating question for techies out there
August 22, 2014 6:21 AM   Subscribe

One of many painful aspects to the James Foley tragedy is that the US attempted rescue, but was in error as to the location of the hostages. I wonder - is there not some geolocating device, maybe even a microchip, that could be required for journalists and tourists/hikers entering a war zone? I can understand that it would be an intolerable risk for soldiers and spies, but Foley was leaving an Internet café when he was abducted - not trying to live a hidden life.
posted by mmiddle to Technology (11 answers total) 1 user marked this as a favorite
There is the spot tracker
posted by exois at 6:24 AM on August 22, 2014

You wouldn't just need a chip, you'd need a whole antenna powerful enough to broadcast a signal across many miles, plus the power source (a relatively huge battery?) to send that signal. So now on top of that difficult-to-impossible engineering challenge, nothing that would scale down to discretely fit inside a human body would be difficult to block. Just the metal in a building kidnappers might use anyway would probably cut down on signals a lot, and building a quick easy Faraday cage to block the signal intentionally would be pretty trivial for terrorist-types who, we know, include a lot of well-educated well-trained engineers.
posted by Tomorrowful at 6:28 AM on August 22, 2014

We already have EPIRBs which do the basic locating and signaling stuff you would want, but are large, conspicuous, easily detected, and probably easily jammed. They're great for most every rescue situation other than terrorism.

Setting aside power and size issues, the basic concept of a signaling device that is detectable by friendly forces over regional/country ranges, but not detectable by hostiles in immediate proximity, is a very difficult problem. I feel that you could maybe use spread spectrum techniques to hide the signal if the hostiles were no closer than a few hundred meters. But if they're in direct contact, even that won't work.

Or maybe you don't care if the terrorists can detect it? If it's implanted in your chest or grafted into your hip bone, they're probably not going to remove it, even if they know it's there. I guess in that case they just shove you into a shielded metal box like a shipping container or something.

This is a hard problem, even when you strip away all the practical product design-type issues.
posted by ryanrs at 7:05 AM on August 22, 2014

I doubt many journalists would wear one, if it existed. If you're trying to cover a war, you're trying to talk to the people fighting it. Those people have enemies they don't want to be found by. If it was known that US journalists were walking around with beacons on them being monitored by the US government at all times, I bet it would sketch out potential sources to the point where it would make journalists' jobs even more difficult than they already are. No one would talk to them.
posted by maggiepolitt at 7:24 AM on August 22, 2014

GPS is a receive-only technology. Your phone knows where it is, but to tell everyone else where you are it uses the cellular network, not GPS.

This means you can tell exactly where you are in the middle of the desert with a tiny receiver and not much power, but to tell anyone else you need either a powerful transmitter or an existing infrastructure to send on.
posted by odinsdream at 7:30 AM on August 22, 2014 [3 favorites]

Or maybe you don't care if the terrorists can detect it?

Well, this. For cases where the person is not trying to hide, and is going around more or less in public. Make it optional, even, with no way to tell who does or doesn't have one. And as long as I'm wishing - maybe even make it so that the individual could turn it off, in situations like the one maggiepolitt flags, and later back on again. Make it so that even if it couldn't be detected within a typical building, it would record, date and archive a trail of where the person was carried in public, from building to building.
posted by mmiddle at 7:40 AM on August 22, 2014

The trouble is that if bad people can detect it, they can also remove it.

I doubt they will rely on aseptic technique when they do.
posted by Pogo_Fuzzybutt at 8:41 AM on August 22, 2014 [1 favorite]

"Required" by whom? Anyway, a Spot tracker is pocket-sized and generally what you're looking for.
posted by craven_morhead at 9:26 AM on August 22, 2014

There are watch-sized EPIRBs too, smaller than the Spot devices. I don't know if they're more than a novelty. The limiting factors for making these devices smaller is battery power and antenna size. There's also no market pressure to make these things covert or tamperproof. Some large ELBs like in airplanes are designed to be hard to destroy in an accident, but then they're enormous.

The current state of the art for consumer emergency locators is that they broadcast at 406MHz to a satellite network. The broadcast includes the person's location, typically determined by GPS. I don't see any technical reason why that transmission couldn't be encrypted so only approved listeners could detect your location, but the public satellite networks aren't set up to do that.
posted by Nelson at 9:55 AM on August 22, 2014

transmission couldn't be encrypted so only approved listeners could detect your location

When the transmission occurs, merely having heard it is enough to get the location - there is no need to decrypt it. Resolving the source of radio broadcasts is 100+ years old science at this point.
posted by Pogo_Fuzzybutt at 10:16 AM on August 22, 2014

Thanks for all these answers. Very discouraging, though. (And, @craven_morhead: "required" by whatever entity or person is funding the taggee, and might be asked for ransom. But I dropped that part of the wish.)
posted by mmiddle at 1:09 PM on August 22, 2014

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