Eric K. Walton, senior research scientist in Ohio State’s ElectroScience Laboratory, who along with his colleagues worked on the project, said the radar’s signal resembles random noise, which makes it almost invisible.

The radar worked by scattering very low-intensity signals across a wide range of frequencies 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. As such a receiver couldn’t detect the signal unless it knew exactly what random pattern to look for.

"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. 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. Due to this, a TV or radio tuned to any one frequency would nterpret the radar signal as a very weak form of static," Walton said.

Like traditional radar, the "noise" radar detects objects by bouncing a radio signal off them and detecting the rebound. However, it can also be tuned to penetrate solid walls, like radio and TV signals.

The radar’s most important characteristic is however, its ability to distinguish between many types of targets because of its ultra-wide-band characteristics.

As such the military could use it for surveillance and pick up enemy soldiers inside a building without the radar signal being detected. Traffic police could measure vehicle speed without setting off drivers’ radar detectors, and vehicle drivers could know what lay beyond a curb or a bush.

"There are thousands of everyday objects that look like humans on radar-even chairs and filing cabinets. So the shape of a radar image alone can’t be used to identify a human. What tends to give a human away is that he moves. He breathes, his heart beats, his body makes unintended motions. These tiny motions could be used to locate disaster survivors who ere pinned under rubble," he said.

"Other radar systems can’t do that, because they are too far-sighted-they can’t see people who are buried only a few yards away. The noise radar is inherently able to see objects that are nearby. It can see things that are only a couple of inches away with as much clarity as it can see things on the surface of Mars," he added.

Walton said that further development of the technology could even be used for medical imaging for mapping tumors, blood clots, and foreign objects in the body. It could also be used to measure bone density.