GPS That Never Fails

Drive down a Manhattan street, and your car's navigation system will blink in and out of service. That's because the Global Positioning System (GPS) satellite signals used by car navigation systems and other technologies get blocked by buildings. GPS also doesn't work well indoors, inside tunnels and subway systems, or in caves--a problem for everyone from emergency workers to soldiers.

But in a recent advance that has not yet been published, researchers at Sarnoff, in Princeton, NJ, say their prototype technology--which uses advanced processing of stereo video images to fill in GPS gaps--can maintain location accuracy to within one meter after a half-kilometer of moving through so-called GPS-denied environments.

Technology Review: GPS That Never Fails