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Definition: Loran from Philip's Encyclopedia

(Long range navigation) Radio system of navigation for ships and aircraft. Pairs of transmitters emit signal pulses that are picked up by a receiver. By measuring the difference in time between the signals reaching the receiver, the vessel's position can be plotted.


Summary Article: loran
from The Columbia Encyclopedia

(lôr'ăn´´), long-range, accurate radio navigational system used by a ship or aircraft to confirm or to determine its geographical position. The term loran is derived from the words long-range navigaton. Loran, operating in the 1,700-kHz range, measures the time-of-arrival difference between two signals transmitted from two geographically separated ground stations. The pulse from the first station, called the master, triggers the second station, called the slave, into transmitting a similar pulse after a set time delay. Knowing the elapsed time difference, the navigator refers to a loran chart and selects his line of position. The chart contains groups of hyperbolic curves of constant time differences between particular station pairs. The position of the receiver (ship or airplane) will be somewhere along the curve that corresponds to the measured time difference. By taking a similar time-difference reading from a second pair of stations whose curves intersect those of the first pair, a definite geographic fix may be obtained.

The Columbia Encyclopedia, © Columbia University Press 2018

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