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GPS + LORAN-C: performance analysis of an integrated tracking system / J. Carroll in GPS world, vol 17 n° 7 (July 2006)

Public [article]  inGPS world > vol 17 n° 7 (July 2006) . - pp 40 - 47 Titre : GPS + LORAN-C: performance analysis of an integrated tracking system Type de document : Article/Communication Auteurs : J. Carroll, Auteur Année de publication : 2006 Article en page(s) : pp 40 - 47 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] GPS assisté pour la navigation (technologies) [Termes IGN] intégration de données [Termes IGN] LORAN (système) [Termes IGN] navigation à l'estime [Termes IGN] performance [Termes IGN] positionnement par GPS [Termes IGN] récepteur Résumé : (Editeur) Before GPS, even before satellites, there was LOng RAnge Navigation, or LORAN. Using terrestrial radio transmitters, it was developed during World War II for aircraft navigation. The wartime system evolved by the mid-1950s into the present day 100 kHz LORAN-C system. LORAN's standard principle of op-eration is hyperbolic positioning. A receiver measures the difference in times of arrival of pulses transmitted by a chain of three to six synchronized stations sep--arated by hundreds of kilometers. The time-difference measurement derived from the signals of two stations, when multiplied by the speed of propagation of the signals, forms a line of position (LOP); the receiver could be anywhere on this line and give the same measurement. The geometrical form of this LOP is a hyperbola. Measurements using a third station provide an-other hyperbola, which intersects the first at the position of the receiver. There are many LORAN chains around the globe. The LORAN system is being modernized to enhance its accuracy, integrity, availability, and continuity. Vacuum-tube transmitters are being replaced with solid-state designs and new primary frequency standards are being installed at transmitting stations. Manufacturers have developed compact LORAN receivers able to track multiple transmitters simultaneously and to automatically apply propagation bias corrections. Some receivers are integrated with GPS or other sensors. Receivers also feature improved antenna designs. Collectively, these improvements are known as Enhanced LORAN or eLORAN for short. Additionally, LORAN signals can be used to convey differential GPS corrections. Such a system is already operational in Europe. Supported by the Coast Guard and the Federal Aviation Administration in the United States, a goal of eLORAN is to provide non-precision approach for aviation users and harbor entrance and approach for marine users. Land users will benefit, too. Since LORAN has different signal characteristics from those of GPS, it can be used in locations where GPS cannot by itself or in conjunction with GPS and other sensors. In this month's column, we look at a system that combines eLORAN with GPS and dead reckoning to overcome some of the problems in navigating in big cities. Copyright Questex Media Group Inc Numéro de notice : A2006-567 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28290 [article]

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