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Comment by kirubakaran | Hacker News Reader

US vehicles have cell-phone jammers

What if they wire it to detonate on a jam? I hope the army has taken this into account (seems obvious that they would have.)

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The jamming equipment has a much larger effective range than an IED. They would go off well out-of-range. (Hopefully there are no civilians in-range!)

It's probably a lot cheaper and easier just to wire it directly and go find a house to camp out in until the vehicles pass.

Not all IDE's are designed the same way. Hence the "I".

The easiest one would just be 3-4 AT mines linked together. This one looks to be anti-personnel/light vehicle, as fuel/air won't really defeat most armour.

Yea, but then you would be nearby when a few dozen pissed off Marines jump off the other trucks in the convoy. Plus air support, tanks etc. The last thing insurgents want to do is be anywhere near the actual fight.

You'd be nearby looking like every other civilian.

And very few shots are fired during an IED strike unless there is the accompanying ambush (That does happen occasionally) inbound. Even Marines don't shoot randomly at things.

SOP on an IDE strike is to secure the area and evac the wounded. That won't involve shooting unless there is reason too.

All you have to do is sit there and relax.

Unless it's a suicide mission.

well you have to be fairly close anyway to make the call (further than a wire I guess, yes, but still)

Seems like that would entail something in the phone that could see if it's connection to the base stations had unexpectedly fallen to almost zero. Assuming this is how being jammed works. This is probably quite hard to do on any non-sdk'd phone, so it might not have come up yet. Iphone prices probably need to drop a bit more...

Cleary a dedicated radio detonator could be programmed to work like this, but then we are talking improvised here.

Radio detonators are not so easy to improvise. So you end up buying off the shelf parts. But since there are many fewer radio controlled devices, this means your signal is a lot easier to trace. The nice thing about cell phones, is that there are a lot of them. And activation can be on a ring. How do you distinguish a hostile call before it has even been answered?

You just need to temporarily setup the network to block incoming calls to the phones in the patrolled area. This does not mean the 'signal' will drop to zero at any time, from the phone point of view. The phone will have absolutely no way to tell a blocked call from a lack of calls.

An even better option: work with the cell providers, so that the US has a back door to deactivate cell towers, but not completely -- just keep them from ringing phones. Then, the US just needs to have software that deactivates ringing of phones hear convoys. If there aren't to many convoys, then this will only be a minor inconvenience.

So they'll find a new way - timer after loss of signal, FRS radio, long-range cordless phones, IR sensors, etc. Worse comes to worse, they'll do it manually and blow themselves up in the process.

This isn't the kind of problem that you can solve with technology - sure, you can make it more difficult, but the people who make these things do nothing else during a day but make IEDs; they'll find a new way to blow things up. Nothing encourages people to tinker with electronics like the perception that their country is being invaded and that they can fight back with bombs.

So take control of their cell system (which, by the way, will do wonders for the perception that the US doesn't run the country) if you want, but don't expect that to change much. The way to beat IEDs is to make it so they don't want to set IEDs, or at least so that you've got enough people who don't want them set that they can report when others are.

That would probably require a more advanced manipulation of the phone. When they trigger on ring, it's probably just using the power to the speaker or something built-in.

cell phones have this neat little 'buzzer' in them to alert you during meetings. It's a little motor with an excentric weight attached to them, when the motor spins the weight will cause the phone to vibrate.

This is almost tailor made to set stuff off by remote. Beta test using the ringer, when it's all good make it hot by switching your profile to 'silent'.

The favored method of IED detonation was just to have the attach a small spool of thread to the motor and have it pull a thread to activate something. Not sure what the favored method is now.

That was a pretty lucky guess then. I swear I never blew anything up, but I love to tinker with stuff. Hooking up a small relay to the motor outputs or using the motor directly seemed like the obvious thing to do.

Ah, good explanation! That certainly seems like the path of least resistance.

Well, won't some easily accessible electrical parameter about the phone change on a call getting cut? Voltage across the battery / speaker output / resistance of mic / something ? They can make a call after setting up the IED, they can just wait for the call to get cut for the IED to explode.

man that would suck if the call got broken early for some other reason...

"This is cingular, your credit is 0, terminating call"

What if the call gets cut off just because it's a bad line? What if the jammer takes effect 500m before the first vehicle? What if the phone runs out of battery, which it will within hours if it's active on a call? Not to mention that finding the IEDs would be much easier if they were radiating like a mobile phone.

All just guesses of course.

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