Original URL: http://www.theregister.co.uk/2012/07/02/bae_navsop/

BAE proposes GPS-less location

Beat the jammers and spoofs

By Richard Chirgwin

Posted in Science, 2nd July 2012 21:59 GMT

Whether or not Iran used GPS spoofing to down a US drone last year, there’s no doubt that GPS spoofing is both real and easier than the military would like. Now, BAE Systems is proposing a positioning technology that works without GPS.

The defence company says its NAVSOP system – Navigation via Signals of Oppurtunity – allows devices to calculate position based on the mass of signals that already surround us.

This, the company says, makes NAVSOP resistant both to GPS jamming, and to spoofing attacks of the kind recently demonstrated by Todd Humphreys (University of Texas, Austin, press release here). In that attack, Humphreys demonstrated a drone takeover using about $1,000 of kit.

By using available signals – from mobile phone towers, fixed broadcast locations like TV and radio, air traffic control radars, and where location data is available, WiFi routers – BAE Systems claims its proposed system isn’t subject to the problems that face GPS navigation.

As NewScientist explains, the company says the heavy regulation applied to signals like broadcasts, radio and radar means both their frequency and the signal strength at the transmitter are known.

That makes them suitable for location calculation by triangulation – and the variety of regulated transmitters means that each signal source can be used to correct errors in others. For example, while mobile base station locations are regulated, it’s not unknown for carriers to move a rooftop base station by a few meters without updating the public record.

By taking advantage of lower-frequency signals that penetrate the mass of concrete of a city location – something that causes problems for GPS – BAE says it can also provide a location fix where GPS units lose sight of their satellites.

BAE notes that the public infrastructure required already exists – so NAVSOP can be rolled out without an expensive build. BAE’s announcement is here. ®