Cheap Cell-Phone Detector

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Posted by timothy on Tuesday July 20, 2004 @07:58PM from the and-tim-gets-10%-for-fairness dept.

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."

18 of 296 comments (clear)

Neat, Now if only by novalogic · 2004-07-20 20:00 · Score: 5, Interesting

... I can tie it into a cellphone JAMMER on my car, so I can detect moron drivers on phones as they come close, and jam them when they become a danger.

I can see police cars equipted with this kinda stuff in places where Yack and Drive is illegal.

These kids are rich.

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1. Re:Neat, Now if only by sr180 · 2004-07-20 20:01 · Score: 4, Funny
  
  Great, so they look at their phone to work out why it dropped out right as they swerve their vehicle into you..
  
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  In Soviet Russia the insensitive clod is YOU!
2. Re:Neat, Now if only by Albanach · 2004-07-20 22:02 · Score: 4, Insightful
  
  I can see police cars equipted with this kinda stuff in places where Yack and Drive is illegal.
  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.
3. Re:Neat, Now if only by tzanger · 2004-07-20 23:29 · Score: 5, Insightful
  
  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.
4. Re:Neat, Now if only by BroccoliGod · 2004-07-21 01:31 · Score: 3, Insightful
  
  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
Cheap Cell Phone detector? by Flerg · 2004-07-20 20:00 · Score: 5, Funny

Why would you want to detect cheap cell phones?
Already have one by shird · 2004-07-20 20:04 · Score: 4, Informative

I already have one, its a set of speakers on my desktop. Everytime a cellphone gets a call/text i get a:

dicky-dick-dicky-dick-dicky-diiiiiick

Also useful for knowing when Im about to get a call and can start looking for my phone well in advance before it starts ringing.

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I.O.U One Sig.
Re:Tracking down specific people by novalogic · 2004-07-20 20:04 · Score: 3, Informative

I would doubt that. First of all, you'd have to do an awful lot of needless "Ping'ing", and if the person knew there was a danger, simply turn the phone off.

And ofcourse, you need to beable to send this kinda stuff, I've seen it reported that IM services keep limited logs of IP's that use that.

Besides, if your gonna stalk someone, and be within 30 meters, AND have an active connection to Yahoo, you'd beable to use better ways to locate the person then a radio ping which may or may not work based on how crowded the area is.

just dosn't seem like a good method based on the way it works.

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Finally! by WegianWarrior · 2004-07-20 20:05 · Score: 5, Funny

...a great way to find my cellphone those times when I put it on silent ringing and then forgets where I put it down :) (don't laught - it happens more often than I like to admidt). Now, if they could also find a way to indicate not just how far away the mobile phone is, but also in what direction... shouldn't be hard - either a directionloop, or two antennas 90 degress apart.

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Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
Got it already by darnok · 2004-07-20 20:05 · Score: 3, Funny

So this thing can detect a mobile phone only when it sends or receives a call or text message? I'm not that smart, but I figure that would tend to coincide with either the phone making a ringing or beeping noise, or someone talking into it.

Hmm, how could I possibly detect this using attachments I've had on my head since birth ...?
This is news? by Captain_Chaos · 2004-07-20 20:10 · Score: 3, Interesting

Come on! We've been getting these for free with our Coke and popcorn for years. I've a small green Heineken bottle that lights up when my cell phone is active, and also a pen with a little red light at the end which does the same.
There's even ones that don't need batteries and work solely on the energy that's broadcast by the phone (although these have to be attached to the phone so they're not much good as "cell phone detectors"). All of these have been around for quite a while (or at least they have here in Europe).
Its easy by FraggedSquid · 2004-07-20 20:12 · Score: 5, Funny

Just listen for somebody shouting "I'M ON THE TRAIN!". As if we didn't know already.

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You don't need a lab to make mud.
Simple explanation on directionfinding by radio by WegianWarrior · 2004-07-20 20:22 · Score: 4, Informative

I often make the mistake of assuming people know what I know... in this cause, how most modern ADF (Automatic Direction Finding) equipment work in aircraft... Mea culpa =)

A coiled antenna - also know as a directionloop - recives the signal strongest when the 'open end' of the coil points towards the transmitter. If you have two coiled antennas, one orientated dead ahead (in relation to you) and the other pointing left-right (ie: being 90 degrees apart), it is reasonable easy to use the difference in signal strenght to figure out the direction the source of the radiotransmitter - in this case the mobile phone.

Three points (or antennas) would be needed if you want a fix on the radiotransmitter (mobile phone) and not just the direction.

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Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
Re:Isn't it Obvious Anyway? by stupid_is · 2004-07-20 20:24 · Score: 3, Interesting

I think that at least one use of them was mentioned in the article (but of course, who reads that, nowadays?) in that students use them on silent mode during exams. Schools aren't necessarily the richest institutions in the world either.

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-- Intelligence is soluble in alcohol
Ears by tiredwired · 2004-07-20 21:01 · Score: 4, Funny

Ears are so cheap I got two of them. I can detect cell phones quite well.
Re:Detect this by Alranor · 2004-07-20 21:04 · Score: 5, Funny

Last I checked this was still the "land of the free".

Just out of curiousity, how many years has it been since you checked that?
Isn't that why the phone rings? by TheOtherAgentM · 2004-07-20 21:11 · Score: 3, Funny

That way you know where the phone is when you get messages or calls. It's always funny to me when the phone rings and someone yells, "Phone!" That's why it rings in the first place.
A number of reasons this device might be practical by SmoothTom · 2004-07-20 21:25 · Score: 3, Interesting

1) It might detect a cellphone being used for sureptitious evesedropping on a conversation

2) It might detect a cellphone in a silent text ony mode receiving test answers

3) It might detect an active cellphone in a secure environment where they are prohibited

Not all potential uses are obvious ones.

Consider the prison example from the article (You did RTFA, right?) - if prisoners are prohibited cellphones and you detect one in use in a cellblock, it is time to do a detailed search...

--Tomas