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Cheap Cell-Phone Detector
An anonymous reader contributes a link to a BBC News article on a cheap cell-phone detector created by six New Zealand high-school students for a business competition, excerpting "The detector, which they have called CellTrac-r, works by picking up the bursts of radio frequency activity that emit from a mobile each time it sends or receives a call or a text message. The device can detect these bursts of electro-magnetic energy up to a radius of 30 metres. It can also measure the amount of the energy to determine the distance of the mobile.", and noting "Seems like a perfect /.er hack project, and as initiator I get 5% of gross profits."
Because the previously inattentive driver wasn't enough a danger, now you have a confused and angered driver more concerned with why his cell phone stopped working than paying attention to the road?
I remember that a couple of years ago you could get a sort of pen that would light up whenever somebody within a certain range (a couple meters) was using his cell phone. The CellTrac-r described in the article sounds like a similar gadget, with possible extra capabilities (like determining the distance).
I would assume that this device can also detect when the cell phone does its intermittent "reaffiliation" with the network, since (as others have pointed out) you would otherwise only be able to detect it when it's in use. At which point I wouldn't really need this detector to find out that they have a cell phone.
I do find it strange that they can detect the range to the mobile phone just by using the signal strength. All network standards worth mentioning include the ability for the transmitters to adapt their power depending on the signal strength at the receiver, so signal strength is not a good indicator of distance.
Score:-1, Wrong
I wouldn't go to the extent as saying that Tait was the largest tech exporter from NZ (OK its a given for hardware, but what about software?) but I think that it's great that they are encouraging kids to be creative and have fun learning about new things (heck, they probably now know more about my own cell phone than I do).
My hat comes of for Tait, and I challenge all those slashdotters in decision making positions to get the kids off the streets and get them involved.
And finally (sorry all those in Aussie, but I can't resist) woo-hoo another Kiwi first!
Karma? Hey I just call it as I see it.
This isn't the point of these things. As lots of people have pointed out, It's pretty easy to detect a phone at short range, as anyone with any kind of small-signal audio system (microphone amplifier, probably even line-level things or higher) can tell you. In fact the first phone I had used to make my (CRT in those days) screen flicker when it was close enough.
But that's not what these things are for. There are plenty of environments where you are *not* meant to have mobiles turned on because: inside planes or in hospitals (both places where there is critically important small-signal electronics), in exams (no electronics, but pervasive cheating by text message), and in many other places. For those environments you want something which will detect a phone at significant range, and you *can't* assume that you can hear someone or the phone ringing: someone trying to cheat in an exam won't have the phone set to ring, and won't be talking into it.
Of course, you can get detectors already, but they're significantly expensive - hundreds of pounds. And you need plenty of them, too. Think about an exam: one for the room itself, one for each toilet, and probably at least one more for the corridors between the room and toilets. 4 or 5, minimum, or several thousand pounds. How many exam rooms does a school use at once? Maybe 5? So they might need 15-20 of these things. Not a small amount of money for a school. Similar things are true for hospitals and so on.
Reducing the cost by a factor of 10 or more, as these people have done, is a *major* advance. So yes, this is news.
I don't drive, though I'm often a passenger in cars. I'm often a passenger on buses too, strange as this may sound to some North Americans. In both situations I'll frequently use my mobile phone - are the police really going to start tracking vehicles and trying to establish if there's more than one occupant? What about single occupant cars with a proper hands free kit installed? What about sensible folk who when driving ignore the fact their phone was ringing and let it divert to voicemail? I really can't see the police wasting much time with this.
Very handy for hospitals whose equipment can potentially be sensitive to the high interference caused by cell phones. (Not going into if they actually are, but when someones life is on line, you don't second guess).
:)
Also for airplanes. As it has been discussed, it's not an issue of interference for the plains electronics, but rather huge stress for the network.
Could be handy to mount some of these at the airplanes ceiling and equip it with a moderately toned piezo buzzer to remind anyone who has forgotten to switch off their phone. Shouldn't get false positives from terminal either while on ground, as the planes are usually more than 30 meters from there.
The piezo buzzer would be probably sufficiently collectively annoying to encourage any bonehead to shut off their phone too
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The only thing that stops me is that it would jam medical pagers for doctors and emergency service reserves on duty..
That, and I'd personally beat you senseless for determining that you have any say whatsoever over my use of a cell phone on a train, bus or any other form of public transit. I am perfectly capable of using my cellphone properly; your use of vigilante justice would earn you some in return.
The only thing that stops me is that it would jam medical pagers for doctors and emergency service reserves on duty..
That, and I'd personally beat you senseless for determining that you have any say whatsoever over my use of a cell phone on a train, bus or any other form of public transit. I am perfectly capable of using my cellphone properly; your use of vigilante justice would earn you some in return.
To paraphrase Ennio Flaiano: "On Slashdot there are two kinds of cell phone fascists: fascists and anti-fascists."
-BroccoliGod