An improvised explosive device (IED), often rigged to detonate from a distance, may be the most common casualty producing weapon in Iraq, but if it uses a radio receiver, it could also be one of the easiest to override, say researchers at the University of Missouri-Rolla.
Radio receivers, such as those found in remote-controlled toys, wireless phones, cell phones, and wireless doorbells, are cheap, readily available devices that are often used to initiate the explosion in an IED, says Dr. Todd Hubing, professor of electrical engineering at UMR.
"At Fort Leonard Wood, Mo., we viewed IED training tapes and saw there are a lot of cases where command-initiated IEDs are placed on the side of the road in a very remote area," says Dr. Daryl Beetner, assistant professor of electrical engineering at UMR. "If a military convoy was able to detect the presence of a radio receiver on the side of the road up ahead, they would be able to react accordingly before it could pose a threat."
Hubing, Beetner and other researchers in the UMR Electromagnetic Compatibility Laboratory are internationally recognized for their ability to track down the sources of unintentional noise in electronic systems for the purpose of minimizing radio frequency emissions. They are now using some of those same tools to detect and identify radio receivers. One of the techniques Hubing and Beetner are using involves capturing the electromagnetic radiation from various radio receivers and slowing it down to make audio signals. Filtering, or pre-processing of the signals, is key to enhancing the sound of a particular receiver.
"It would be relatively easy to override these radio receivers if we could recognize them," Hubing says. "If we could identify the receiver, we could prevent an IED from ever receiving the initiation signal. In many cases, it would also be possible to send a signal that would set off the explosives before they could pose a threat."
Initially the researchers plan to develop a device that a passenger in the first vehicle of a military convoy could use to listen to, identify and locate radio receivers. "This would be similar to sonar detection on submarines, where you have a person who is listening to the sounds that are out in the ocean," Beetner says. Ultimately both researchers would like to provide the military with automated detection using an artificial neural network or other technique to recognize unusual sounds.
"There’s way too much information to play it back in real time," Hubing says. "Right now we’re capturing 100 milliseconds of data and we’re taking 10 seconds to play it back. But we are also looking at other ways of presenting the signal. For example, we could intelligently change the size of the sample by having the computer listen and only play back what it decides is interesting for us to hear."
The researchers believe that in a year, with funding, they could develop a system for soldiers to identify and locate radio receivers in remote areas. "Presumably we’d be able to hear anything electronic, particularly if it had a processor in it and there was a lot of electrical activity," Hubing says. "This project started as an effort to identify automobiles based on their radio frequency emissions. This turned out to be much easier than we anticipated. We shifted our focus to radio receivers when we learned of the urgent need in this area."