Stealth radar system sees through trees, walls -- undetected
COLUMBUS, Ohio -- Ohio State University engineers have invented a radar system that is virtually undetectable, because its signal resembles random noise.
The radar could have applications in law enforcement, the military, and disaster rescue.
Eric K. Walton, senior research scientist in Ohio State's ElectroScience Laboratory, said that with further development the technology could even be used for medical imaging.
He explained why using random noise makes the radar system invisible.
"Almost all radio receivers in the world are designed to eliminate random noise, so that they can clearly receive the signal they're looking for," Walton said. "Radio receivers could search for this radar signal and they wouldn't find it. It also won't interfere with TV, radio, or other communication signals."
The radar scatters a very low-intensity signal across a wide range of frequencies, so a TV or radio tuned to any one frequency would interpret the radar signal as a very weak form of static.
"It doesn't interfere because it has a bandwidth that is thousands of times broader than the signals it might otherwise interfere with," Walton said.
Like traditional radar, the "noise" radar detects objects by bouncing a radio signal off them and detecting the rebound. The hardware isn't expensive, either; altogether, the components cost less than $100.
The difference is that the noise radar generates a signal that resembles random noise, and a computer calculates very small differences in the return signal. The calculations happen billions of times every second, and the pattern of the signal changes constantly. A receiver couldn't detect the signal unless it knew exactly what random pattern to look for.