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Evaluation of single frequency GPS precise point positioning assisted with external ionosphere sources / Reza Ghoddousi-Fard in Advances in space research, vol 57 n° 10 (May 2016)  

Public [article]  inAdvances in space research > vol 57 n° 10 (May 2016) . - pp 2154 - 2166 Titre : Evaluation of single frequency GPS precise point positioning assisted with external ionosphere sources Type de document : Article/Communication Auteurs : Reza Ghoddousi-Fard, Auteur ; François Lahaye, Auteur Année de publication : 2016 Article en page(s) : pp 2154 - 2166 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] couche atmosphérique [Termes IGN] ionosphère [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur bifréquence [Termes IGN] récepteur monofréquence [Termes IGN] teneur totale en électrons Résumé : (auteur) Single frequency code and single frequency code and phase GPS precise point positioning scenarios using various ionospheric sources are evaluated by assessing their performances with respect to dual frequency solutions. These include Canadian regional and global vertical total electron content (VTEC) maps produced by Natural Resources Canada and different International GNSS Service (IGS) coordination or analysis centres. Furthermore, two of the most commonly used single layer ionospheric mapping functions applied for conversion of VTEC to slant TEC are evaluated with each and every one of the ionospheric VTEC sources. Results show that the quality of code only solutions depends on ionospheric activity level, and the TEC map and mapping function selected. Code and phase single frequency solutions are also improved when assisted with an external ionosphere source. Numéro de notice : A2016-270 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2016.02.017 En ligne : http://dx.doi.org/10.1016/j.asr.2016.02.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80804 [article]

Online precise point positioning: a new, timely service from Natural Resources Canada / Y. Mireault in GPS world, vol 19 n° 9 (September 2008)

Public [article]  inGPS world > vol 19 n° 9 (September 2008) . - pp 59 - 64 Titre : Online precise point positioning: a new, timely service from Natural Resources Canada Type de document : Article/Communication Auteurs : Y. Mireault, Auteur ; P. Tetreault, Auteur ; François Lahaye, Auteur ; et al., Auteur Année de publication : 2008 Article en page(s) : pp 59 - 64 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] Canada [Termes IGN] positionnement ponctuel précis [Termes IGN] serveur web [Termes IGN] temps réel [Termes IGN] traitement de données GNSS Résumé : (Editeur) Meliora sequamur - let us strive to improve. The words that the Roman poet Virgil wrote some 2,000 years ago could well be the watchwords of those scientists and engineers who today work to improve the accuracy, coverage, and timeliness of GPS-based positioning. They are particularly appropriate for those seeking to improve the technique of precise point positioning or PPP. PPP is a single-receiver positioning technique just like conventional pseudorange-based positioning, which takes place inside a receiver. However, the similarity stops there. PPP uses the receiver's very precise undifferenced carrier-phase observations together with very precise (and accurate) satellite orbits and clocks to achieve positioning accuracies at the few centimeter level or better. And unlike differential techniques such as real-time kinematic (RTK) positioning, all of the physical phenomena affecting the measurements must be very accurately modeled. These include solid earth tides, ocean-tide loading, transmitting and receiving antenna phase-center offsets and variations, carrier-phase wind-up, relativistic effects, and so on. With differential techniques, such effects are greatly reduced and typically become insignificant, especially on short baselines. PPP can be used to process data collected at a fixed (static) site or along a trajectory in kinematic mode or a mixture of the two - "stop and go" PPP. Although introduced in the late 1990s, PPP has only become more commonplace in the past few years, thanks, in part, to continued PPP development in government and university research labs. Several PPP processors are even available online. The precise satellite orbits and clocks required are provided by the International GNSS Service (IGS) and its worldwide tracking network and analysis centers. These products are supplied with some latency resulting in PPP normally being used as a post-processing technique with observations being processed some time after they are collected. However, over the past year or so efforts have been made to reduce the latency of some high-precision products. In particular, the ultra-rapid orbit and clock product of the Geodetic Survey Division of Natural Resources Canada (NRCan) is now being produced with a delay of only 90 minutes. Coupled with NRCan's online PPP engine, it provides positioning accuracies almost as good as the IGS final product, which is only available with a delay of about two weeks. In this month's column, we take a look at this new, timely service from the Great White North. Copyright Questex Media Group Inc Numéro de notice : A2008-384 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29377 [article]

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GPS time transfer: using precise point positioning for clock comparisons / François Lahaye in GPS world, vol 17 n° 11 (November 2006)

Public [article]  inGPS world > vol 17 n° 11 (November 2006) . - pp 44 - 49 Titre : GPS time transfer: using precise point positioning for clock comparisons Type de document : Article/Communication Auteurs : François Lahaye, Auteur ; D. Orgiazzi, Auteur ; P. Tavella, Auteur ; G. Cerretto, Auteur Année de publication : 2006 Article en page(s) : pp 44 - 49 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] Global Positioning System [Termes IGN] mesurage de pseudo-distance [Termes IGN] phase GPS [Termes IGN] positionnement ponctuel précis [Termes IGN] récepteur bifréquence [Termes IGN] récepteur GPS [Termes IGN] temps atomique international Résumé : (Documentaliste) Les auteurs relatent les résultats d'une expérience menée avec la méthode de transfert de temps "Precise Point Positioning PPP" de post-traitement des données GPS par comparaison avec les mesures de transfert de temps et fréquence du satellite par 2 voies (Two-Way Satellite Time and Frequency Transfer TWSTFT). La méthode PPP permet une précision au niveau de la nano-seconde, sans avoir recours au réseau des stations. Numéro de notice : A2006-474 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28198 [article]

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Monitoring GPS receiver and satellite clocks in real time: a network approach / François Lahaye in GPS world, vol 12 n° 11 (November 2001)

Public [article]  inGPS world > vol 12 n° 11 (November 2001) . - pp 44 - 50 Titre : Monitoring GPS receiver and satellite clocks in real time: a network approach Type de document : Article/Communication Auteurs : François Lahaye, Auteur ; P. Collins, Auteur ; Pierre Héroux, Auteur ; J. Popelar, Auteur Année de publication : 2001 Article en page(s) : pp 44 - 50 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] contrôle métrologique [Termes IGN] Global Positioning System [Termes IGN] poursuite de satellite [Termes IGN] récepteur GPS [Termes IGN] satellite GPS [Termes IGN] temps atomique international [Termes IGN] temps réel Résumé : (Auteur) The Global Positioning System is made possible, in large part, by the use of atomic frequency standards onboard the satellites and at the tracking stations here on the ground. These standards, both rubidium vapor cells and cesium beam tubes, control the timing and frequency of the signals emitted by the satellites. They possess the required characteristics of very high stability and high accuracy. Once set to the correct time, clocks driven by these standards maintain the correct time to within tiny fractions of a second for long periods. But no clock, not even an atomic one, is perfect. The performance of individual clocks in the satellites and at tracking stations is compared against GPS System Time which is a synthetic or"paper"time scale derived from the clocks in all of the satellites as well as those at the GPS Control Segment tracking stations. This time scale is kept closely aligned to Coordinated Universal Time (UTC) as maintained at the US. Naval Observatory (ignoring UTC leapseconds). In addition to the use of GPS for the monitoring and maintenance of the system clocks, GPS is used by the wider precise time and time interval community for synchronizing clocks and frequency standards around the globe. In this article, a team of researchers from the Geodetic Survey Division of Natural Resources Canada describes a technique they have developed for monitoring the performance of both GPS receiver and satellite clocks in real-time using a regional network of tracking stations. Numéro de notice : A2001-129 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21825 [article]

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