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."
... 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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Why would you want to detect cheap cell phones?
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.
I.O.U One Sig.
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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...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.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
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
If it can pick up cell phones in a 30 metres radius, one would have to think that in a conjested area, it may pick up many cellphones and possibly confuse the system. Also I would like to know if this device could interfere with peoples mobile calls, if so, cell phone jammers (this one isnt pocket sized) are already avaialable.
Oh no, not another overused joke!
Christchurch is the technology centre of New Zealand, and Tait is the largest technology exporter
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).
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).
mobile power output varies and is controled by the phone, you can't derive distant by looking at power output.
There was an unknown error in the submission.
Just listen for somebody shouting "I'M ON THE TRAIN!". As if we didn't know already.
You don't need a lab to make mud.
There are so-called "quiet" SMS that the police use for tracking cell phone users. These are SMS without text payload which "ping" the mobile phone without ever showing up on the display.
Of course, their tracking method goes a bit different: they triangulate the distance from the towers. Since every cell phone tower consists of an array of antennas, you can simply measure on which antenna the signal is strongest for an approximate direction. Combined with the distance measurement (from signal strength), this gives quite a nice accuracy (~100m). Of course, that would be of no use on large events, but it's enough to track, say, a software patent violator in the woods.
Note that here (in Germany) you officially need a judges permit to actually use this technique, but since these messages are basically invisible, their use without permit is to be strongly suspected. Here is an article (in German) dealing with this topic.
so that the MPAA goon squads can kick your out and confiscate your phone before you can text all of your friends and warn them not to waste their money of whatever shitty movie you had the misfortune of seeing first.
LK
"Hi. This is my friend, Jack Shit, and you don't know him." - Lord Kano
Just think about it.
Give it 4 or 5 years, and mobile phones on new generation networks will have high resolution image stabilised digital cameras and the ability to transmit this image in real time, already compressed, down multi-megabit networks.
Such a phone would video a movie from a pocket, and there would be no evidence, because it would be transmitted away.
So there is a huge value in these detectors...
Just remember to leave your mobile at home when you visit the cinemas, or having it ring during the movie will only be the start of having a very very bad day...
GrpA
Enjoy science fiction? "Turing Evolved" - AI, Mecha, Androids and rail-gun battles. What more could you want?
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.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
-- Intelligence is soluble in alcohol
In HK, one of the most cellphone popular place, some karaoke do have such facility. Once the detector received any signal from the cellphone, it will display a sign on on the screen and minimize the background sound automatically to avoid effecting the conversation of the phone owner.
Just dial their phone and follow the ring tone!
Brought to you by the tin hat brigade.
#hostfile 0.0.0.0 primidi.com 0.0.0.0 www.primidi.com 0.0.0.0 radio.weblogs.com
If they sold these devices with a pair of rubber gloves, they are onto a winner!
#hostfile 0.0.0.0 primidi.com 0.0.0.0 www.primidi.com 0.0.0.0 radio.weblogs.com
Hardly a new idea. as a commercial device a bit odd and of dubious use. I know my phone, nokia 3595 i think, makes any amp;lifiers near it buzz loudly when its updating the clock or receive calls. obviously some phones are more suceptible to being pick up then others.
We've secretely replaced the Enterprise's dilithium crystals with Folgers crystals. Lets see if they notice.
I've seen something similar to this before. This one however is slightly different (there are two ICs in the one from the article. For those who don't understand electronics, the incoming signal goes into an operational amplifier, and this will compare the incoming signals with that of a fixed voltage (from a battery). This then drives a MOSFET (like a transistor) to switch a load on and off. I would guess that the second IC in the new device is to measure the distance (v x == close) from the signal level). I build the circuit in the PDF, and it has a range of a few meters, but could be improved, if you had the parts/time.
If you want an exact conversion, 30 metres is equal to 3000 centimetres ;)
But think of buildings collapsed during earthquakes. May be helpful there!
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Unless the USA is way behind the time I would say the majority of people have cellphones hence it is similar to people choosing to pick on people with 2 hands. In terms of search and seizure laws I guess this gets a little trickier. My 1st reaction was well your cell is broadcasting so it would the same as telling people to not listen when you are shouting. However what if the equipment would be capable of listening to your conversation that would kind of be spying and I am not so keen on that idea. But is it really different to someone eavesdropping on your conversation in public. So torn. /back to work
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
Ears are so cheap I got two of them. I can detect cell phones quite well.
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?
But I just thought that my comment about being a Kiwi first is probably going to start a huge thread about reading the artical and getting my facts straight. What I meant was that it is a first that it is so cheap $40 compared to $1000. And it is a design so simple that a child could make it (although I must admit that I would have to try an remember which way up you hold a circuit diagram before I atempt it).
Karma? Hey I just call it as I see it.
It's not just everytime you get a call or text message. Sometimes I hear that sound even though I don't receive a call or a message. It might have something to do with the phone changing from one cell tower to another or something, or simply being polled by the cellular operator.
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.
Now if they could only invent something so that when i'm using a cell the person on the other end of the call can actually hear me and not just static and noise... You won't need a fancy device to find me... I'll have one finger in my ear and be screaming profanity throughout the duration of the call... You'll hear me from way more than 30 meters away!
All the torrents you could want.
I'm DEAF, you insensitive clod!!!!!
...mobile phone holders that had flashing led's that sold for £1.99
If you have nothing useful to say post as AC.
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
A detector will tell you that a phone is being used in a restricted area, but it won't help you find it that easily - especially if there are several in a room. The easiest solution for something like an exam room is a cellphone jammer. In saying that, this will only remedy exchange of information via cellphone. It will not prevent people from using their phones as calculators or as notebooks. So if you want to ensure that there is absolutely no cheating in an exam where no calculators are allowed, I would suggest an EMP grenade :)
"Seems like a perfect /.er hack project, and as initiator I get 5% of gross profits."
How about.. no.
This message was brought to you by the death of 30 brain cells.
Whoa! I completely misunderstood this based on the headline. I thought it would detect which cell phones were cheap.
once i tried to record a voicemail message using a tape recorder held to the earpiece of my cell phone.
(yeah stupid, but what you gonna do?)
"yeah CLICK we're gonna CLICK go to jack in the CLICKox and we're going to CLICK pick up some more beer... you'd better CLICK not be in lab CLICK or i'm gonna kick your CLICK..."(end message)
detecting that RF bullCLICK should be easy.
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http://www.hellection.com
How selective is this thing anyway? I cannot see anything which might be a filter on the board, so does it only pick out cell phone frequencies? Or also wireless headphones, wireless (non cellular) telephones, wireless car locks,...
Z
My guitar amp, if turned up loud enough, makes clicking noises when I have a cell phone in the room, and it starts buzzing and clicking a few seconds before my cellphone rings. I wonder if this is related.
It's annoying because it does this even if the ringer is off (obviously), and has ruined more than a couple recording sessions.
Detecting active conencted phone is not so difficult. This still does not apply to phone at airplane detection.
Wish they could find a way to detect phone that is not in call.
It is a fair warning, but doesn't seem likely that in the next 10 years phones will be able to transmit movies over 'multi-megabit networks', if only because of power constraints. Having you phone ring during the movies is a bad idea already...
Z
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
The fact that such detectors give out a strength reading that can be used to determine distance gives the opportunity for three or more to be used together in a theater setup. A phone wouldn't even have to ring, just the session establishing contact with the towers is enough, at which point the circles could be drawn to find their intersect point and they'd know where to send an usher to prevent the mid-show interruption before it happens.
Now when my phone is in the glove box and someone trys to call or sends a text I'm going to get arrested.
thank God the internet isn't a human right.
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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It will not detect a off device. A bad guy who wants to sneak in and start calls from a secured facility can simply turn off his fone, put it inside a coke can and then turn it on when apropiate.
[]'s Victor Bogado da Silva Lins
^[:wq
I think a cheap detector for cell phones is meant.
And now having exhausted the day's ration of pedantry, to work.
Panurge has posted for the last time. Thanks for the positive moderations.
How is this news? People have been selling cheap decorative bands for mobile phones, pens and other items that light up moments before a cell phone lights up.
It's quite popular with the ladies over here and they are onlyh about RM$5 - 20 each.
So these kids put in 4 LEDs instead of 1. Big deal.
Sometimes I wish I was a plumber, then I'd know how to deal with other people's shit.
Actually I have two - my mp3 player and my walkman. Every time I'm listening to one and my cell phone is about to ring (or another one nearby is) I hear a very distinct pattern of interference in my headphones.
or about 750 chicken eggs.
1 chicken egg == 4cm
or about 166,67 SEDS
1 SEDS (Standard European Dick Size) == 18cm
...you're still going to need a damn camera, and be filming with it. I doubt they'll be able to integrate that in the phone with a usable quality, and even if they did it wouldn't be in your pocket. That would pretty much be a give-away even if there's no recording. Combined with some testimony from whoever caught you, I don't think the defense will fly...
Kjella
Live today, because you never know what tomorrow brings
Since every cell phone tower consists of an array of antennas, you can simply measure on which antenna the signal is strongest for an approximate direction. Combined with the distance measurement (from signal strength), this gives quite a nice accuracy (~100m).
Except that signal strength is dynamically altered by GSM and all other advanced mobiles - you don't want the mobile transmitting at full strength all the time, just the minimum amount to get through reliably because:
1. Your battery life will be pitiful if max power is used
2. You will "Jam" one frequency/timeslice over the whole radius of your transmission.
The big advance of GSM over Analog phones (similar with CDMA I believe) is that they could work well with high basestation densities, and they do this by keeping the power down, not up.
So signal strength does not tell you how far away the phone is.
Michael
There is no cryptographic solution to the problem where the intended receiver and the attacker are the same entity.
Wasn't there a remotely detonated bomb using a cellphone a while back? Bomb squads could use the device to sniff out transmitters.
Too bad I got the patent on rolling money. But for $699... ah forget it.
ANYTHING that works by broadcasting a signal can be detected. Cellphone, cordless phone, spark-ignition, even your PC's emissions. That's life; deal with it.
If you don't want "snoopers", don't broadcast. So there's a solution to your concerns: turn off your cellphone when you're not actively talking. Periodically check voicemail, preferably while in a crowded area, where "they" can't track you down.
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Another proof of the superiority of CDMA over GSM for cheating :-). GSM uses a modulation scheme that is easy to detect with relatively simple electronics. CDMA phones output a signal that looks like wideband white noise at a very low power level. It's difficult to detect or jam.
Mea navis aericumbens anguillis abundat
As a teacher's assistant, I would love to have one of these for those pesky cheaters using text messages.
...it's called an unshielded speaker. Whenever any data is being transmitted by my phone, my speakers go nuts.
Based on the distance from the speaker (or wire), I can tell how far away the phone is.
On a serious note, the device is simple. The complex part comes in if they can triangulate the actual 2D or even 3D position of the phone, not just the radial distance. Then I'll be impressed...
It's called a field strength meter, and can be made with a diode, capacitor and typically an analog meter. When the needle deflects, you have electromagnetic energy in the area. Add one or more tuned circuits to it and you narrow it down to the cell phone band(s).
Move along. Nothing to see here.
I have one somewhere...actually it's a pen/cell phone dectector/black light...it's slow to pick up my GSM phone but CDMA pops the light on in about 3 seconds...
That happens on our telephone and TV as well. More of a soft popping sound.
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I don't know anything about cell phone protocols, but if phones send some sort of indication of current power level the tower could still make some kind of estimate. In fact, given all the hoopla about this technology, I wouldn't be surprised to find that cell phones do apprise the tower of their power output.
The higher the technology, the sharper that two-edged sword.
Of course, this quip made him lose the business competition. If he was a real businessman he would have patented it and charged a 50% licensing fee.
If you were within 30m of them to begin with. If you think that's a privacy concern, you need help. I mean, you can hear someone's ringtone further than that - are they privacy concerns too??
My crappy speakers make a noise 2 seconds before my phone or my neighbor's cell phone starts ringing.
This whole "signal strength" strength is a boat load of red herrings.
I don't know how the tracking software works per se, but you can bet your backside that it probably employs:
1. Which cell [antenna cluster] you're logged into
2. Which sector of the cell you're using (around here, there's usually three, and they are directonal)
3. What the TDMA transmit delay is
3 is a little less obvious -- GSM uses TDMA to divvy up the channel. The phone and the tower need to know how far apart they are, for speed-of-light reasons -- this is why cellular switches are all run off atomic clocks.
Since we know the time for the signal to reach the phone, we know how far away it is. We also know the direction (down to 120 degrees).
Finally, GSM phones keep tabs on up to six nearby towers, and the GSM network must know which ones the phones can see in order to do tower handoff.
So, now we have a several approximate vectors and distances. It shouldn't be hard to come up with their intersections. I think it can be done with two angles and two distance measurements.
Do daemons dream of electric sleep()?
Asymetric attacks. Most of these are set off by cell phones. Granted this doesn't really give you much of a warning.
Can you detect a phone that isn't being used?
seems like it could cause some definite privacy concerns.
Well the target is using a device that broadcasts a signal on common frequencies. If you are using a device that broadcasts a signal, there can be no privacy concerns relative to emission. Thats like telling the other team the exact play with _no_ encryption before the snap and getting pissed when they acknowledge it. If you are that nuts about privacy, dont talk or type and stay home.
Are you intolerant of intolerant people?
Yeah, me too, but it's not only during a call or text. Apparently, my phone (a Nokia 6340i on Cingular) periodically contacts the network -- either it's auto-setting its clock or just checking in with Big Brother. For a while, at first, I had no idea why I was hearing these weird little chirps from my speakers, until I noticed they also happened right before I received a call.
I can see this technology being implimented in the classroom where most mobile devices are prohibited, especially in high-schools. Professors get sooo agitated when someones cell goes off... This may help them in detecting if students are messaging during class... or even worse... a test.
A hundred dollars or so.
Evenif it was illegal.
Why would you need this. I can detect a cell phone without it. Look at a person... cell phone detected. Everyone has one now, including 6 year old kids.
Civil Aviation Authority's experimental results for cell phone usage.
The CAA is the British equivalent of the FAA. The FAA has not done the same tests for itself. Instead it has relied on the CAA's data and erred on the side of caution.
And not all of the avionics are located on the flight deck. The avionics, especially things like flight control computers, are distributed throughout the aircraft in a redundant system.
"We can't solve problems by using the same kind of thinking we used when we created them." -- Albert Einstein
Hard to tell from the pictures, but it's unlikely to be a very selective receiver. Which suggests it's going to have a large false-trgger rate from nearly any RF emitter, such as wireless doorbells, wireless thermometers, wireless lightswitches, old flourescent bulbs, police and fire radios, gas meter telemeters, garage door openers, wireless headphones, and even wireless network hot spots. Needs a little work.
"works by picking up the bursts of radio frequency activity"
Wow they invented the radio receiver.
And automatically shoot the bastards.
<^>_<(ô ô)>_<^>
It got them a win in the competition.
You just need to look for the person with the backpack-sized battery....
Such a phone would video a movie from a pocket, and there would be no evidence, because it would be transmitted away.
But why would anyone want full-motion stabilized video of the inside of my pocket?
~Idarubicin
Friends don't help friends install M$ junk.
and usually people can detect it. About 30 seconds into the conversation, they'll ask, "Are you in the car?".
But sometimes they'll say that while I'm simply walking outside and trying to not get hit in a parking lot...
THIS THING CAN TURN ON A DIME, MACROSSZERO STYLE ALSO FUCK BETA, ~NYORON
Now if only they had hooked it up to a really distracting flashing bunch of LEDs...
Then, as its so cheap and easy to manufacture, they could start putting them into everything... like cellphone antennas and stickers and such...
Then you could sell them at the cell phone booths at mall for $20.
gee.
Just about any set of self-amplified multimedia speakers can detect cell-phone transmission bursts if the phone is held reasonably close (within a foot or so).
Designing an RF section to cover the cell bands would easily give the thing range in the 10's of meters.
So it's obvious, and you get nada.
...why the TV starts buzzing a couple seconds before my phone rings?
I mod down pyramid schemes in sigs.
It might have been off topic but it was not flamebait. There is a law in the US that won't allow jammers. Every time a cell phone goes off in a movie there are another 50 - 100 people that want that law changed. There are places where they are banned already, let it sound off in a court room and find out what contempt of court is. The inconsiderate behavior of cell users is what causes the problem.
Professional Politicians are not the solution, they ARE the problem.
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I am currently working in Shanghai, China... And considering the amount of mobile phones around here I really wonder how efficient this device would be here! I mean there's probably something like an average of 3 mobile phones every square meter... So I would imagine the device would just panic and blow up or something!!
Yeah. Would you choose a neurosurgeon who pokes around people's brains in his spare time? I wouldn't.