However, to do the same to the Loran system, you'd need a 40ft tower -- and around 25kW of juice to power it.

ENGADGET

Just one year ago, the Bush administration announced it would keep the ground-based LORAN system operational to serve as a backup for the satellite-based global positioning systems, which are becoming ubiquitous in cars, planes and ships.

CNN: Navigation system, aid to farmers among budget cuts

It's always nice to see an old tech stage a comeback and this time it's happening around the coasts of Europe, with nine low-frequency radio transmitters substituting for GPS' satellite-based system. eLoran's radiowave-based system is stronger than satellite signals and less jammable, based on the Loran system that was previously used for shipping navigation by both the British and US navy over 50 years ago.

ENGADGET

Having LORAN in reserve makes the GPS satellite system a less attractive target for terrorists, they say.

CNN: Navigation system, aid to farmers among budget cuts

Each probe can pick up GPS signals and signals from eLoran, an enhanced version of Loran, the ground-based terrestrial radio-navigation system first used by the American and British navies during the second world war.

ECONOMIST: GPS jamming