Loran-C is a
hyperbolic radio navigation system which allows a receiver to determine its position by listening to
low frequency radio signals transmitted by fixed land-based
radio beacons. Loran-C combined two different techniques to provide a signal that was both long-range and highly accurate, traits that had formerly been at odds. The downside was the expense of the equipment needed to interpret the signals, which meant that Loran-C was used primarily by militaries after it was first introduced in 1957.