It combines a conventional global positioning system (GPS) signal with those of other sensors - accelerometers and gyroscopes - to pinpoint a car's location to within 2m (6ft 6in).

BBC: Spanish scientists develop more accurate sat-nav system

The Air Force learned how to take out any enemy it could find a generation ago when it began deploying munitions that could utilize the very accurate military signal transmitted by Global Positioning Satellites.

FORBES: Air Force Positions For Resurgence In Pacific Era

Inside, Williams explains, is a receiver tailored to make use of a signal from an atomic clock carried by a global positioning system satellite.

FORBES: Magazine Article