/lawr"an, lohr"-/, n.
a system of long-range navigation whereby the latitude and longitude of a ship or airplane are determined from the time displacement between radio signals from two or more fixed transmitters.
Also, Loran.
[1940-45, Amer.; lo(ng) ra(nge) n(avigation)]

* * *

abbreviation of long-range navigation

A land-based system of radio navigation in common use over the continental United States and in its coastal waters.

It was developed during World War II for the U.S. military. A civilian version, Loran-C, was developed in the 1950s. Loran-C can be used to determine position within about 30 ft (10 m) by comparing signals from multiple stations. Loran-like systems operate in many coastal waters around the world. However, the availability of the global positioning system (GPS), with a typical accuracy of 3 ft (1 m), has begun to relegate loran to backup status.

* * *

▪ radio navigation
abbreviation of  long-range navigation 

      land-based system of radio navigation, first developed at the Massachusetts Institute of Technology during World War II for military ships and aircraft located within 600 miles (about 970 km) of the American coast. In the 1950s a more accurate (within 0.3 mile [0.5 km]), longer-range system (over 2,000 miles [3,200 km]), known as Loran-C, operating in the 90–110 kilohertz range, was developed for civilian use, and the original loran (renamed Loran-A) was phased out. Eventually, Loran-C was extended to cover most of the continental United States and, in cooperation with Canada and Russia, Canadian waters and the Bering Sea. Numerous other countries have deployed loran-like systems as well. It is still used by many marine craft, but the precision (typically within 30 feet, or 10 metres) of satellite-based navigational aides, such as the global positioning system (GPS) (GPS), is increasingly relegating land-based navigational systems to the status of backup systems.

      Loran is a pulsed hyperbolic system. This means that hyperbolic lines of position are determined by noting differences in time of reception of synchronized pulses from widely spaced transmitting stations, primary and secondary. A primary station broadcasts an uninterrupted series of pulses of fixed duration and at a fixed rate (e.g., of 50 microseconds' duration at a rate of 25 pulses per second). A secondary station, 200–300 miles (320–480 km) away, automatically transmits its own signals, maintaining a frequency and pulse duration in accord with those of the primary station. The secondary station maintains a fixed time difference between its reception of the primary signal pulse and the sending out of its own. The noted time difference of arrival of the two pulses locates the craft somewhere on a curve (hyperbola) every point of which is located at a constant difference in distance between the stations (e.g., is three miles farther from the primary than from the secondary). Tuning in another secondary station locates the craft on another hyperbola, so that its position can be fixed at the intersection of the two.

* * *

Universalium. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • loran — loran …   Dictionnaire des rimes

  • LORAN — (LOng Range Aid to Navigation) is a terrestrial radio navigation system using low frequency radio transmitters that uses multiple transmitters (multilateration) to determine location and/or speed of the receiver. The current version of LORAN in… …   Wikipedia

  • LORAN-C — LORAN (Long Range Navigation) ist ein Funknavigationssystem, das vorwiegend zur Navigation in der Seefahrt und in der Luftfahrt verwendet wird. LORAN C Mast in Rantum auf Sylt …   Deutsch Wikipedia

  • LORAN — (Long Range Navigation) ist ein Funknavigationssystem, das vorwiegend zur Navigation in der Seefahrt und in der Luftfahrt verwendet wird. LORAN C Mast in Rantum auf Sylt …   Deutsch Wikipedia

  • Loran-C — LORAN Pour les articles homonymes, voir Loran (homonymie). Le LORAN (LOng RAnge Navigation) est un système de radionavigation utilisant les ondes d émetteurs terrestres fixes pour établir une position. Il s agit du seul système hauturier à base… …   Wikipédia en Français

  • LORAN — (англ. LOng RAnge Navigation)  радионавигационная система наземного базирования. Система LORAN была разработана Альфредом Лумисом (en:Alfred Lee Loomis) и широко использовалась кораблями ВМС США и Великобритании в годы Второй мировой… …   Википедия

  • LORAN —   [Abkürzung für englisch long range navigation »Langstreckennavigation«], während des Zweiten Weltkrieges in den USA entwickeltes Hyperbelnavigationsverfahren, das nur relativ wenige Sendestationen erfordert, um in einem großen Gebiet, wie z. B …   Universal-Lexikon

  • loran — [ lɔrɑ̃ ] n. m. • 1946; mot angl., acronyme de Long Range Aid to Navigation « aide à grande distance à la navigation » ♦ Techn. Système de radionavigation utilisé dans la marine et l aviation, fondé sur la détection de l occurrence de signaux… …   Encyclopédie Universelle

  • loran — LORÁN s.n. (Nav.) Sistem de radionavigaţie pentru distanţe mari, constând în determinarea poziţiei unei aero(nave) cu ajutorul semnalelor emise de două perechi de staţii terestre ale căror coordonate sunt cunoscute. – Din engl., fr. loran. Trimis …   Dicționar Român

  • Loran — can refer to one of the following:*LORAN, the terrestrial radio based navigation system. *Loran (cassette), a brand of blank audio cassette made out of Lexan plastic. *Sir Loran of Trollpyre Keep, a fictional character in the World of Greyhawk… …   Wikipedia

  • Loran — Lor an (l[^o]r [a^]n or l[=o]r [a^]n), n. [Acronym, from LOng RAnge Navigation] (Naut., aviation) A system of electronic navigation in which a vessel or aircraft determines its latitude and longitude by measuring the time differences between low… …   The Collaborative International Dictionary of English

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”