A new positioning system uses the same signals used by mobile phones, TVs, radios and WiFi rather than navigation satellites, its British developer says.

The Navsop technology by BAE Systems could complement or even replace current global positioning systems, could help find victims inside buildings during a fire or locate stolen vehicles hidden in underground parking lots, and could even be used in a war if the current satellite navigation system were turned off or damaged, researchers said.

The device works by picking up all the available signals nearby, heavily relying on medium-wave radio frequencies.

Mobile phones, radios and TVs use signals that are a lot more powerful than those from navigation satellites, since they are broadcast from only a few miles away and cannot be jammed.

"Let's be clear -- for Navsop to start learning, you have to have a GPS signal, to know where you are on the face of the Earth," Ramsey Faragher, principal scientist at the BAE Advanced Technology Centre, told the BBC.

However, he said, "The more the system is used the less it relies on GPS for further learning, and reaches the point where it doesn't need GPS at all to function or to carry on learning about new signals.

"We are not saying that our technology should necessarily replace GPS, but rather complement it," Faragher said.

"If the GPS signal is there, by all means, use it. If not, we say that with Navsop, you can determine your position anyway."