By listening to the complexity of radio signals that pervades the human environment, BAE Systems thinks its new positioning system is as accurate as, but more secure than, GPS. Because its Navigation via Signals of Opportunity (NAVSOP) system uses a wide range of signals such as Wi-Fi signals and radio and TV broadcasts, it's resistant to the jamming or spoofing of individual signals to which GPS is vulnerable.

The use of radio, especially medium wave, means that NAVSOP can be used where GPS cannot, inside large buildings specifically. Perhaps more surprisingly, BAE claims NAVSOP will also work in the Earth's most remote locations, including the Arctic, by picking up signals from satellites in low Earth orbit.

However, its main advantage, according to BAE, is that all the infrastructure required to make use of it already exists. No additional transmitters are necessary. NAVSOP learns as it goes, so even unidentified radio signals can be added to its database. BAE claims that even the signals of GPS jammers could be used for navigational purposes.

"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," BAE's Dr. Ramsey Faragher told the BBC while demonstrating a large NAVSOP system in the back of a car. This isn't necessarily a problem, though, as BAE envisages NAVSOP technology would be built into navigation devices along with GPS in order to complement or replace it in the event of satellite signals becoming unreliable or unavailable.

Faragher argues that NAVSOP's potential as a backup to GPS is enormous. "The European Commission determined that €800 billion (US$1 trillion) of the European economy is dependent on either precision navigation or precision timing from GPS," he told the BBC. "The aviation industry, the shipping industry, agriculture, telecommunications, all need GPS to function."

By the time its commercially available, NAVSOP equipment should shrink to a size comparable to GPS receiver, and Faragher suggests the technology may be of interest to countries developing other satellite navigational systems such as China (Beidou) and Russia (Glonass).

Unsurprisingly, BAE has military applications in mind, "from aiding soldiers operating in remote or dense urban areas to providing improved security for Unmanned Aerial Vehicles, which could face attempts to disrupt their guidance systems." Civilian applications are also envisaged, including the possibility that NAVSOP could help fire departments navigate smoke-filled buildings.

A commercial launch date has not yet been tabled.

Sources: BAE Systems, BBC