Eye in the Sky’s detection technology repeatedly located the position of this known smuggler’s tunnel between the United States and Mexico in Douglas, Ariz., even though it was 40 feet underground (entrance shown in inset photo).

That challenge was taken by a pair of small Southwest companies to help save the lives of those forces on the ground in Iraq and Afghanistan and now to support national security.

In the autumn of 2004 Advanced Ceramics Research (ACR) of Tucson, Ariz., teamed with Stolar Research Corp of Raton, N.M., to respond to a Phase I Small Business Innovative Research (SBIR) grant through the Office of Naval Research (ONR) to detect command detonation wires using ACR’s Silver Fox unmanned aerial vehicle (UAV). The challenge was not finding the technology to detect the wires. The challenge was transitioning the Stolar hand held gradiometer technology used in the mining industry, to an airborne device capable of locating IED wires and even tunnels.

The basic operating principle broadcasts a radio wave around an area of interest and then detects changes in the reflected field gradient due to the presence of conductors such as wires. The clever part of the technology allows the receiver system to filter out the original radio wave that can be thousands of times stronger, to trace the reflected signals from targets of interest that would otherwise be indecipherable from the original radio wave. The UAV-mounted gradiometer traverses the regions of interest detecting the reradiated field gradient and mapping the positions of IED detonation wires.

UAV history was made Dec. 10, 2004 when a team from Stolar joined the flight crew and technical team from ACR sponsored under a Navy SBIR program, for the first successful airborne wire detection demonstration near Tucson. In March 2005 the Silver Fox UAV fitted with an eight foot diameter transmitting antenna used a fiber optic link to tow a gradiometer array 70 feet behind it, successfully detecting a range of IED detonation wire gauges from low flying altitudes. This configuration demonstrated the ability of the transmitter and receiver to be flown together from a small tactical UAV.

The first flight success during the four-month ONR SBIR Phase I supported getting a NAVAIR Phase II SBIR award that allowed significant improvements to the technology and detection technique to be undertaken. Seven more development spirals were flown starting in March 2005. System improvements continued through 2005 into 2006 that enabled a tunnel detection demonstration in August 2006. During the tunnel detection demonstration the gradiometer was mounted directly onto a UAV and a ground-based transmitter was used to stimulate the tunnel. Several flights over the area of interest showed that the detection technology could repeatedly locate the position of a known smuggler’s tunnel between the United States and Mexico in Douglas, Ariz., setting another UAV industry milestone.

The continued need for improved border security made the technology attractive to the Department of Homeland Defense Science and Technology Directorate and in cooperation with the NAVAIR Commercialization Pilot Program (CPP) has sponsored continued development for 2007 and 2008.

Unfortunately, technologies that detect tunnels have met with limited success. Intelligence related information indicates that many tunnels exist but are undetected because technology has not reached significant maturity to identify voids in large geographic areas. Improvements to the detection system will result in a more compact and sensitive system allowing autonomous UAV surveillance of our borders to be demonstrated in coming months.

Technology demonstrations on the Silver Fox airborne gradiometer are ongoing, and results are being evaluated. Task Force Troy (Iraq) just recently completed a successful Military User Evaluation of the Silver Fox UAS in Baghdad has been requesting the UAS gradiometer-based IED wire detection technology for further evaluation.