Determining the position of vessels

Shipping requires increasingly greater precision to determine, for instance, the position of a vessel.

Navigation systems using radio-electric waves measure the travelling time of these waves which propagate at the speed of light. The Loran-C system, which works by means of terrestrial transmitters, can determine a position to within 30 metres, which is equivalent to a time signal accuracy of 1/10,000,000th of a second. An even more sophisticated navigation system called GPS (Global Positioning System) relies on a series of satellite-based transmitters.