A cutting-edge radar system has begun providing early warnings of icebergs to the Hibernia oil rig off the East Coast of Canada. The unique technology, more than a decade in the making, will soon be guarding against drug smugglers, illegal immigrant traffickers, foreign fishing vessels - potentially, even terrorists - lurking far out to sea on Canada's Atlantic seaboard. The radar uses the ocean's salty surface as an electronic conduit to track vessels and aircraft as far as 370 kilometres into the North Atlantic.

The so-called "surface wave" hugs the curvature of the earth, reaching to the very edge of Canada's 200-nautical-mile economic zone, unlike traditional radar technology, which is limited to lines of sight less than a quarter that distance. The system has limits - electromagnetic interference at night reduces the range and high waves can mask the presence of smaller vessels, such as fishing trawlers. Surface-wave radar is also ineffective over Arctic ice. At the same time, the signals are not affected by weather and the system provides real-time tracking, with updates of vessel locations every five minutes or so. The system can even be used to measure distant ocean currents to help build a clearer picture of the ocean environment. Raytheon Canada and National Defence build two unmanned research installations in Newfoundland.

These Newfoundland stations are already tracking threatening icebergs for the operators of the Hibernia oil rig. Surface-wave radar installations cost about $5 million each to build and less than $200,000 a year to operate. Meanwhile, National Defence has been given $43.1 million to build as many as six additional sites on both the East and West coasts, with construction expected to begin in the summer of 2005.

The concept of surface-wave radar has its origins in Britain during the Second World War, but the concept was impractical until the advent of powerful computers that can decipher the signals.