Loran, LAWR an, stands for long range navigation. It is a system of radio navigation that helps ships and aircraft find their positions. A master station and two or more secondary stations continually send out radio signals. The ship or aircraft receives these signals with special equipment. The equipment measures the time interval between the pulses that it receives from the stations. The difference in time between receiving the signals from one pair of stations places the ship or the aircraft at some point on a loran line of position on a chart. The chart is marked to show the position of the ship or the aircraft according to the difference in time between the signals.