Thoughts on IEDs
Off-topic, but always hoping somebody in DARPA or suchlike would pick up an idea I've had.
From what I hear, most IEDs are detonated by cell phones or walkie-talkies. Thus if you had a detector for these, you would have a passable IED detector.
Radio receivers actually radiate a bit. Processing the signal requires moving it up and down in frequency (some functions are best handled at high frequency, some at low). You have crystals generating a radio signal and mix it with the incoming signal. This means that the receiver also transmits. I seem to remember that shortwaves gave off 455 h or maybe khz. This is, btw, why they make you turn off cells at takeoff. A cellphone should thus give off a characteristic frequency, as would a walkie-talkie (dunno if they'd be the same). I also believe a cell gives off some signal so that the stations can keep track of just where you are in case there's an incoming call. That signal would be fairly powerful. There are also very broad spectrum receivers that search for ANY radio emissions nearby at any frequency. They're used to search for bugs and are cheap (since they have no tuning section).
Simplest proposal: detector on a pole, like a long metal detector. Use it to probe suspicious packages. If the guy detonates it, at least you're 10-20 ft away rather than opening it.
More elaborate: a directional Yagi antenna can focus reception and improve range by a factor of ten to twenty. At high frequencies like this, it'd be quite small. You might be able to spot a cell phone from a good distance, and know its direction (just sweep back and forth, listening for the strongest signal). Might even have enough range to spot the phone of the guy waiting to set it off. A continuous sweep could spot anything in the road ahead. Might be able to get ranges of hundreds of yards, if cell phones emit signals to tell the system where you are. Cost of antenna is under a hundred bucks, mfrg cost probably five bucks.
Or mount the detector on a toy remote controlled car, and run it up to the package.It'd be close enough to spot radiation from a walkie-talkie in that event.
UPDATE in light of comment: you could probably reduce false positives. The local detector on a pole or remote control toy car could be set to only alert if a cell is within five or ten feet. Sensitivity of one connected to an antenna could be set to alert only if a cell is in the direction the antenna points and within, say, fifty yards. If the antenna is pointed at a person when it alerts, it probably is a false positive. If it's pointed at empty road or a trash bag by the side of it... bingo. The rig could be built for a lot cheaper than a cell phone jammer. (I note the Warlock systems jammers look like they cost $15,000 each. This could be made for around a hundred. And wouldn't just jam the system while a convoy is near it, but would alert you to its location).
Further nasty thought: for the cell to tell its tower where it is, the signal it sends must identify itself. If you could intercept that signal, with help from the wireless phone co. you could determine its number. Post someone to watch it. When someone comes to retrieve it for relocation, dial the number.
FURTHER update: I found a British company that sells a cellphone detector for about $200. Says its good to 40 ft., and you could extend that greatly with the right directional antenna. Here's another, said to have a range up to 30 meters. With regard walkie-talkies ... I think they have a limited number of frequencies. Rig a transmitter that will sweep across these, link to a directional antenna, and you might be able to detonate the bombs ahead of you. At least until they start putting in countermeasures, requiring that the detonating signal convey some information, etc.
While I'm at it, a tip from Vietnam days. Chain link fence does great against RPGs, but they ought to invent something to defeat them. All it takes is a small dent in the nose cone. RPGs detonate when a piezoelectric crystal in the nose is crushed on impact and sends out an electrical signal. The signal passes via the outer casing to the detonator, then back via the inner shell. Dent the outer shell a bit and it shorts out. Stop it without anything hitting the nose and it doesn't function. I've wondered if an armored vehicle couldn't be protected by narrow metal slats pointing outward, maybe a couple of inches apart. If the RPG hits a slat square, it'll still detonate, but if it hits between them it might short. I've tried to figure out how to send a radio/magnetic pulse that would detonate one (now wouldn't that be fun--set off any RPG round in the launcher) but don't have the expertise to figure a way around the fact that it's basically two coaxial conductors, which is pretty resistant to a pulse.
Slat armor is already being employed on armored vehicles. You can see it on this pictures from StrategyPage. It wouldn't be that hard to produce something that could detect a cell phone in the area, the problem is the number of false positives would be very high. Cell phones operate anywhere from 900MHz to 1900MHz, depending on the system. I think 900MHz is more common overseas. These frequences are in the microwave range. You wouldn't even really need something as sophisticated as a device to detect the minute RF output of a reciever, since cell phones also have a transmitter in them that's in constant communication with the cell base.
The solution that we seem to be employing is just to jam all cell phones withing a given area of American patrols. This is probably effective, though it would probably not be hard to make an IED trigger on the signal emitted by the jamming equipment, but presicion detonation would be a problem.
Posted by: Sebastian at April 4, 2006 03:46 PM
Warlock Green and Red already exist.
Posted by: Phanatic at April 4, 2006 05:31 PM
All very good ideas. The problem I see is when we get fixated on one solution. Don't underestimate the enemy, they are very adaptive. We've got to play to our strengths. I think those are our training, resilliency, and will to bring the fight to them.
Posted by: Jared McLaughlin at April 4, 2006 08:59 PM
Cell phones definitely transmit a "heartbeat" signal several times a minute at all times when the power is turned on (regardless of whether or not there is a call going on). This heartbeat signal is picked up by the nearest cell towers, and based on signal strength determines which tower will be used to transmit & recieve call data to your phone.
Frequencies used are standardized so that your cell phone will work no matter where you go.
So yes, it should be easily possible to build a detector that looks for the heartbeat signals, and use the signal to help locate IEDs.
Posted by: Rick at April 5, 2006 08:44 AM
Another thought on the great cell debate. Remote voting of Cell Towers. As a convoy or patrol rolls through an AO, they can either jam, or somehow remote disconnect a specific cell tower or series of towers to cut the receiving phone's reception. Yeah, calls would be dropped, but they ain't paying for it anyway. This would be especially great for SF Teams when they do ops by limiting Mr. Murphy's chance appearance. Chances are, the insipient little Ahmed the Assassin will be nearby, thus causing him to adapt his methods.
Tom Clancy wrote about something similar in "Rainbow Six," but it required an on site operator. If there were a way to update all towers with specific programming, a mission commander could simply disable all phones in the area but phones recognized by the software. That could help other alphabet agencies, contract security, and KBR types trying to use the cell phone infrastructure for their comms.
Posted by: shooter at April 5, 2006 10:07 AM
Comments (second hand information - son was in Iraq)-
He had a cell phone jammer in his humvee. So, they never had a cellphone-detonated IED go off near them. Unfortunately, almost every IED was controlled by a simple timer (to delay arming it until the setter was out of range) and triggered by a $20/pair Motorola FRS radio, and they had a few of those.
Probing suspicious objects with a signal sniffer is good, but RBF is the usual method.
You have to identify the object as suspicious. A little gas on the asphalt to make it brittle, bust it out, dig a hole and bury the IED in it, throw the chunks of asphalt back in to make it look like the start of a pophole. Have any idea how many potholes there are in Iraqi roads? It makes (pick east-coast city to make fun of) look good.
Another problem is the ROE; IED goes off, a hundred yards away, some bird pops up and runs away across a field. Tackling him (with a hundred yard head start!) is ok, plugging the little b******d is a sure ticket to a court-martial and DD.
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Posted by: bud at April 5, 2006 02:05 PM
Couple of years ago, when the IDF was fully involved with Hamas and Al-Aqsa Brigades, it seems that they developed a device that could trigger ANY IED remotely. Trouble was, it used megawatts of power, and could only be carried in the heaviest of large helis or on a 10-ton military vehicle. It also had the tendency to fry things in it's vicinity.
It worked, though, and many IEDs were detonated while still in bomb-factories, or cars being transported.
I believe the device worked on the principle of induction into the firing-squib circuits, reliably introducing a firing current into any electrically-detonated device (all of them, no one lights fuses anymore).
In any case, the IDF's loss rate due to IEDs dropped off to nothing, and very soon, the slopes abandoned using IEDs at all.
Posted by: Rivrdog at April 6, 2006 12:22 AM