With both the US and Russia researching Global Positioning System (GPS) jamming, it's heartening to see boffins working on navigation systems that don't rely solely on satellite signals.
Research led by the University of California Riverside (UCR), and presented at a navigation system conference in mid-September, demonstrated how far the world has come in using all the other radio signals that surround us.
The researchers note that current GPS navigation, even supplemented by inertial navigation systems (like gyroscopes), isn't accurate or reliable enough for fully-autonomous vehicles.
Working with assistant professor Zak Kassas, UCR PhD candidate Joshua Morales supplemented an inertial-plus-satnav system with receivers that get a fix on ambient radio signals – Wi-Fi, AM/FM radio, mobile phone signals, TV transmissions and the like.
Using these “signals of opportunity” (SOOs) is challenging, however. The navigation system can't assume it knows their exact location, so instead, as the UCR paper explains (PDF), the on-board receivers learn the signals' timing. If the vehicle moves, the timing of the ambient wireless signals changes – and that can provide enough information to maintain accurate positioning information even if the navigation system temporarily loses sight of the GPS satellites.
A second paper demonstrates an SOO system specifically focussing on using LTE base stations, which provide more structured timing and location data.
The Register notes that the organisation which runs GPS standardisation, The Aerospace Corporation, is factoring external location sources into the design of GPS 2.0. ®