Mobile phone 'sniffer'

Idunno · 4th May 2002, 18:22

Here's an interesting little gizmo. Found it in a magazine called "How to wind up a moderator". The website is www.crayola.com and the full plans for the instrument are available on their website under the 'mini projects' link.

Could be very useful to pilots! Anyone know how much it would cost to get one built? I'm not an electronics person myself. Any volunteers to build one?

Quote:

Mobile Phone Sniffer
track down mobile phones using this handy directional finder
Design by B. Kainka

In some situations and locations, the use of a mobile phone is forbidden. You may be discussing sensitive information in a closed meeting or holding important exams. How can you be sure that a concealed phone is not being used to pass information outside? Maybe you’re just curious and would like to know if someone nearby is using a phone. This neat unit will not only detect the presence of mobile phone activity (voice or text), it can home in on the culprit!

If you are not familiar with the characteristic RF pulses sent out by a mobile cell phone just go over to an FM radio and switch the mobile on or off while holding it close to the radio aerial. These radio frequency (RF) pulses are an annoyance to amateur radio enthusiasts because they always seem to be picked up by sensitive input stages and you sometimes hear them on Outside Broadcast television programmes where people close to the presenter are using a mobile.
Detecting these pulses is not difficult;

edited by What_does_this_button_do?

SpinSpinSugar · 5th May 2002, 09:49

Such devices exist, Southland, I believe they are illegal in the UK though, unfortunately. If I remember correctly they are configured for such areas (resteraunts, cinemas, etc.) where mobiles are an extreme annoyance, and work by intercepting and returning each network request to a local phone with a "this phone is switched off" signal.

Would be nice to have a belt sized unit sometimes

Soddit · 5th May 2002, 10:59

Total cost should not exceed €10.Source : Maplin Electronics current catalogue. Construction appears straightforward and should take less than 5 hours depending how long it takes you to etch the pcb.

Idunno · 5th May 2002, 22:18

Soddit, (nice handle), can you make them? Or do you know someone who can perhaps?

Maybe we could arrange a 'group order' to make it worth your while.

I'll have one for starters!

gofer · 6th May 2002, 15:24

Anybody ever thought of using something like that in a walk through archway as people go down the catwalk to the plane - so that all those bloody things can be switched off !!!

Especially as they will then take so much longer to switch back on when needed in the ultimate case of highjacking or saying goodbye to the loved ones.

Just a thought....

GeneralElectric · 7th May 2002, 15:37

Looks easy enough to construct once you get the PCB template made. Not really a job for the hobbyists favourite - VeroBoard!!

Just a couple of thoughts.... it only works with EITHER 950 OR 1800MHz phones as it stands (you'd have to cut the antennae down by half to get the higher frequency). Slight annoyance!

Also what about the tri-band phones too? Can't remember the freq range used in the States so it may not work for all.

Maybe you could fix 2 antennas of different lengths and use a toggle switch to select either antenna.

gofer · 7th May 2002, 15:45

The US frequency is 1900 - because they think they are 100% better.

X-QUORK · 7th May 2002, 16:54

You'd be on very shaky ground legally if you start interfering with cellphone frequencies. Here in the UK it is illegal to do so, and with the litigation culture of the US you'd be playing with fire.

I agree that cellphones can be very annoying when they're left on in restaurants, cinemas, etc, but the answer isn't to start jamming the signal.

What_does_this_button_do? · 22nd May 2002, 20:16

I'm watching.....

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