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Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements / German Olivares-Pulido in Journal of geodesy, vol 95 n° 11 (November 2021)  

Public [article]  inJournal of geodesy > vol 95 n° 11 (November 2021) . - n° 122 Titre : Ionospheric tomographic common clock model of undifferenced uncombined GNSS measurements Type de document : Article/Communication Auteurs : German Olivares-Pulido, Auteur ; Manuel Hernández-Pajares, Auteur ; Haixia Lyu, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction ionosphérique [Termes IGN] horloge du satellite [Termes IGN] mesurage par GNSS [Termes IGN] modèle ionosphérique [Termes IGN] phase [Termes IGN] positionnement ponctuel précis [Termes IGN] teneur totale en électrons [Termes IGN] tomographie par GPS [Termes IGN] voxel [Termes IGN] Wide Area Augmentation System [Vedettes matières IGN] Traitement de données GNSS Résumé : (auteur) In this manuscript, we introduce the Ionospheric Tomographic Common Clock (ITCC) model of undifferenced uncombined GNSS measurements. It is intended for improving the Wide Area precise positioning in a consistent and simple way in the multi-GNSS context, and without the need of external precise real-time products. This is the case, in particular, of the satellite clocks, which are estimated at the Wide Area GNSS network Central Processing Facility (CPF) referred to the reference receiver one; and the precise realtime ionospheric corrections, simultaneously computed under a voxel-based tomographic model with satellite clocks and other geodetic unknowns, from the uncombined and undifferenced pseudoranges and carrier phase measurements at the CPF from the Wide Area GNSS network area. The model, without fixing the carrier phase ambiguities for the time being (just constraining them by the simultaneous solution of both ionospheric and geometric components of the uncombined GNSS model), has been successfully applied and assessed against previous precise positioning techniques. This has been done by emulating real-time conditions for Wide Area GPS users during 2018 in Poland. Numéro de notice : A2021-776 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-021-01568-8 Date de publication en ligne : 13/10/2021 En ligne : https://doi.org/10.1007/s00190-021-01568-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98839 [article]

SBAS-aided GPS positioning with an extended ionosphere map at the boundaries of WAAS service area / Mingyu Kim in Remote sensing, vol 13 n° 1 (January-1 2021)  

Public [article]  inRemote sensing > vol 13 n° 1 (January-1 2021) . - n° 151 Titre : SBAS-aided GPS positioning with an extended ionosphere map at the boundaries of WAAS service area Type de document : Article/Communication Auteurs : Mingyu Kim, Auteur ; Jeongrae Kim, Auteur Année de publication : 2021 Article en page(s) : n° 151 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] correction [Termes IGN] correction ionosphérique [Termes IGN] décalage d'horloge [Termes IGN] GPS assisté pour la navigation (technologies) [Termes IGN] orbite [Termes IGN] positionnement par GNSS [Termes IGN] retard ionosphèrique [Termes IGN] Wide Area Augmentation System Résumé : (auteur) Space-based augmentation system (SBAS) provides correction information for improving the global navigation satellite system (GNSS) positioning accuracy in real-time, which includes satellite orbit/clock and ionospheric delay corrections. At SBAS service area boundaries, the correction is not fully available to GNSS users and only a partial correction is available, mostly satellite orbit/clock information. By using the geospatial correlation property of the ionosphere delay information, the ionosphere correction coverage can be extended by a spatial extrapolation algorithm. This paper proposes extending SBAS ionosphere correction coverage by using a biharmonic spline extrapolation algorithm. The wide area augmentation system (WAAS) ionosphere map is extended and its ionospheric delay error is compared with the GPS Klobuchar model. The mean ionosphere error reduction at low latitude is 52.3%. The positioning accuracy of the extended ionosphere correction method is compared with the accuracy of the conventional SBAS positioning method when only a partial set of SBAS corrections are available. The mean positioning error reduction is 44.8%, and the positioning accuracy improvement is significant at low latitude. Numéro de notice : A2021-075 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13010151 Date de publication en ligne : 05/01/2021 En ligne : https://doi.org/10.3390/rs13010151 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96813 [article]

Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites / Jeongrae Kim in GPS solutions, vol 19 n° 3 (July 2015)  

Public [article]  inGPS solutions > vol 19 n° 3 (July 2015) . - pp 423 - 431 Titre : Using ionospheric corrections from the space-based augmentation systems for low earth orbiting satellites Type de document : Article/Communication Auteurs : Jeongrae Kim, Auteur ; Young Jae, Auteur Année de publication : 2015 Article en page(s) : pp 423 - 431 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales [Termes IGN] correction ionosphérique [Termes IGN] données GRACE [Termes IGN] European Geostationary Navigation Overlay Service [Termes IGN] orbite basse [Termes IGN] orbitographie [Termes IGN] signal GPS [Termes IGN] système d'extension spatial [Termes IGN] teneur totale en électrons [Termes IGN] Wide Area Augmentation System Résumé : (auteur) For low earth orbit satellite global positioning systems (GPS) receivers, ionospheric delay corrections from space-based augmentation system (SBAS) can be considered for real-time use. Due to the different total electron contents between ground and low altitude orbits, a scaling factor is required to adjust the ionospheric corrections. After an analysis of the scale factor determination with GPS data from the NASA/DLR gravity recovery and climate experiment satellite is conducted, evaluations of WAAS, MSAS, and EGNOS ionospheric correction accuracies are performed. In terms of the ionospheric correction error in 2012, SBAS outperforms GPS broadcast with the reduction of 42 %. This SBAS ionospheric correction accuracy shows a high level of correlation with solar flux F10.7. Numéro de notice : A2015-462 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0402-8 Date de publication en ligne : 22/08/2014 En ligne : https://doi.org/10.1007/s10291-014-0402-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77138 [article]

The WAAS L5 signal: an assessment of its behavior and potential end use / H. Rho in GPS world, vol 20 n° 5 (May 2009)

Public [article]  inGPS world > vol 20 n° 5 (May 2009) . - pp 42 - 48 Titre : The WAAS L5 signal: an assessment of its behavior and potential end use Type de document : Article/Communication Auteurs : H. Rho, Auteur ; R.B. Langley, Auteur Année de publication : 2009 Article en page(s) : pp 42 - 48 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] signal GPS [Termes IGN] signal multidimensionnel [Termes IGN] test de performance [Termes IGN] Wide Area Augmentation System Résumé : (Auteur) The recent launch of the GPS Block IIR-20(M) satellite and the commissioning of its L5 demonstration payload herald the beginning of a bright new era in space-based positioning, navigation, and timing. The new satellite signal is anticipated to provide better-quality range measurements and possibly improve the tracking performance of a GPS receiver compared with current civil L1 and L2 signals through use of improved signal structures. The L5 signal will be standard on the future Block IIF and Block III satellites. However, some readers may be surprised to learn that L5 signals have been continuously transmitted by a pair of satellites for the past several years. The geostationary Earth-orbiting (GEO) satellites used by the U.S. Federal Aviation Administration's (FAA's) Wide Area Augmentation System to provide enhanced integrity and accuracy include not only an L1 payload but an L5 payload as well. While the WAAS L5 signals have been broadcast from space for some time, they did not come from a satellite in medium Earth orbit, and so it was necessary to include the demonstration payload on the GPS Block IIR-20(M) satellite to guarantee the L5 frequency filing with the International Telecommunication Union. There are some differences between the WAAS L5 signals and the future fully fledged GPS L5 signals. The WAAS L5 signals only use a single-channel carrier (there is no quadrature or Q channel) and the data rate is 250 bits per second (bps) rather than 50 bps. The WAAS signals are actually generated on the ground and relayed through the GEOs using a "bent pipe" approach. The FAA uses the L5 signals, in conjunction with the L1 signals, to compute ionospheric delays as part of the closed-loop control of the broadcast signals. Although the WAAS L5 signals are not yet intended for end users, can they be used now for positioning and navigation and, if so, are there any caveats? In this month's column, I am joined by one of my graduate students, Hyun-ho Rho, who has looked at the WAAS L5 transmissions, examining their signal strengths, multipath characteristics, and instrumental bias issues. Precise positioning performance of WAAS pseudoranges has also been assessed as an independent check on instrumental bias compensation by the WAAS control segment. The favorable results point to a future of the L5 signal, on both the WAAS satellites and the next-generation GPS satellites, which is bright indeed. Copyright Questex Media Group Numéro de notice : A2009-178 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29808 [article]

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Good, better, best: expanding the wide area augmentation system / T. Schrempp in GPS world, vol 19 n° 1 (January 2008)

Public [article]  inGPS world > vol 19 n° 1 (January 2008) . - pp 62 - 67 Titre : Good, better, best: expanding the wide area augmentation system Type de document : Article/Communication Auteurs : T. Schrempp, Auteur Année de publication : 2008 Article en page(s) : pp 62 - 67 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] navigation aérienne [Termes IGN] transport aérien [Termes IGN] Wide Area Augmentation System Résumé : (Editeur) Air travel promises to become safer and cheaper thanks to the Wide Area Augmentation System (WAAS). It assists or augments GPS by providing the increased accuracy, availability, continuity, and integrity necessary for aircraft navigation. Unaugmented, or standalone, GPS isn't accurate enough for some types of runway approach procedures. Using geostationary Earth orbit (GEO) communications satellites, WAAS provides corrections to the GPS satellite orbit and clock information in a satellite's navigation message as well ; as ionospheric delay information. These corrections permit a user's receiver to compute a more accurate position, often to better than 1 meter horizontally and 2 meters vertically, with a 95% confidence. WAAS also increases the availability and continuity of GPS for aircraft navigation by requiring fewer redundant observations for determining a valid position. Availability is also increased through the provision of the additional GEO ranging signals. But perhaps most importantly, WAAS provides the increased integrity needed for a safety-of-life navigation system. Within 6 seconds of a fault detection, an alarm message corrects the error or allows a safe transition to an alternative navigation procedure. The advantages of WAAS for aviation include greater runway capability, reduced separation standards which allow increased capacity in a given airspace without increased risk, more direct enroute flight paths, new precision approach services, reduced and simplified equipment onboard aircraft, and significant government cost savings due to the elimination of maintenance costs associated with older, more expensive ground-based navigation aids. But WAAS not only benefits GPS users in the sky. Many GPS users on terra firma are making use of the increased accuracy and availability afforded by WAAS. For example, according to the FAA, OnStar has added WAAS capability to the GPS receivers in General Motors 2008 product year vehicles. And even surveyors are making use of the WAAS ranging signals for improving real-time kinematic survey operation. While WAAS was already a much-valued addition to standalone GPS, significant improvements were made to WAAS over the past three years, including expansion of the reference station network and the commissioning of two new GEOs. 2008 will see even more enhancements. In this month's column, we take a look at WAAS's recent upgrades and take a peek into its future. Copyright Questex Media Group Inc Numéro de notice : A2008-161 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29156 [article]

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Mise en place d'une procédure de post-traitement GPS pour du lever cadastral massif / Fabien Coubard (2007)

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GNSS update: positive and negative developments / Huibert-Jan Lekkerkerk in Geoinformatics, vol 9 n° 5 (01/07/2006)

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Early results are in testing a prototype Galileo receiver / N. Gerein in GPS world, vol 16 n° 11 (November 2005)

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Applied satellite navigation using GPS, Galileo, and augmentation systems / R. Prasad (2005)

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Performance analysis of the real-time Canada-wide DGPS service (CDGPS) / M.E. Cannon in Geomatica, vol 58 n° 2 (June 2004)

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Navigation : principles of positioning and guidance / Bernhard Hofmann-Wellenhof (2003)

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Effect of ice loading of a GPS antenna / K. O'keefe in Geomatica, vol 54 n° 1 (March 2000)

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Compte-rendu de réunion "Civil GPS Service Interface Committee (CGSIC)", Kansas City, USA, 14-15 septembre 1997 / Pascal Willis (1997)

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