loran—A method of applying pulse techniques to navigation. The term is a contraction of the phrase long range navigation.” A pulsed transmitter (called “master station”) triggers one or more other pulsed transmitters (called “slave station”), which may be as much as several hundred miles away. A mobile receiver is provided, which can accurately measure the difference in time of arrival of the coded signals or pulses from the master and slave stations. If such a receiver is moved so as to keep a constant time difference, it will follow a hyperbolic path. A number of such paths can be drawn on a chart for each set or pair of the high-power, permanent, land-based stations used Several sets of stations make possible a chart containing many intersecting families of such hyperbolas. A ship or airplane equipped with the proper receiver can locate its position on a hyperbola for each of two or most sets of stations. By noting where these hyperbolas intersect on the charts, the position fix is found.

loran lines—Lines of constant time difference between signals from master and a slave loran station.

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Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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