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Measuring phase scintillation at different frequencies with conventional GNSS receivers operating at 1 Hz / Viet Khoi Nguyen in Journal of geodesy, vol 93 n°10 (October 2019)  

Public [article]  inJournal of geodesy > vol 93 n°10 (October 2019) Titre : Measuring phase scintillation at different frequencies with conventional GNSS receivers operating at 1 Hz Type de document : Article/Communication Auteurs : Viet Khoi Nguyen, Auteur ; Adria Rovira-Garcia, Auteur ; José Miguel Juan, Auteur ; et al., Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] artefact [Termes descripteurs IGN] filtre passe-haut [Termes descripteurs IGN] glissement de cycle [Termes descripteurs IGN] horloge du récepteur [Termes descripteurs IGN] ionosphère [Termes descripteurs IGN] mesurage de phase [Termes descripteurs IGN] oscillateur [Termes descripteurs IGN] phase GNSS [Termes descripteurs IGN] récepteur GNSS [Termes descripteurs IGN] retard ionosphèrique [Termes descripteurs IGN] scintillation [Termes descripteurs IGN] teneur totale en électrons [Termes descripteurs IGN] zone équatoriale Résumé : (auteur) Ionospheric scintillation causes rapid fluctuations of measurements from Global Navigation Satellite Systems (GNSSs), thus threatening space-based communication and geolocation services. The phenomenon is most intense in equatorial regions, around the equinoxes and in maximum solar cycle conditions. Currently, ionospheric scintillation monitoring receivers (ISMRs) measure scintillation with high-pass filter algorithms involving high sampling rates, e.g. 50 Hz, and highly stable clocks, e.g. an ultra-low-noise Oven-Controlled Crystal Oscillator. The present paper evolves phase scintillation indices implemented in conventional geodetic receivers with sampling rates of 1 Hz and rapidly fluctuating clocks. The method is capable to mitigate ISMR artefacts that contaminate the readings of the state-of-the-art phase scintillation index. Our results agree in more than 99.9% within ± 0.05 rad (2 mm) of the ISMRs, with a data set of 8 days which include periods of moderate and strong scintillation. The discrepancies are clearly identified, being associated with data gaps and to cycle-slips in the carrier-phase tracking of ISMR that occur simultaneously with ionospheric scintillation. The technique opens the door to use huge databases available from the International GNSS Service and other centres for scintillation studies. This involves GNSS measurements from hundreds of worldwide-distributed geodetic receivers over more than one Solar Cycle. This overcomes the current limitations of scintillation studies using ISMRs, as only a few tens of ISMRs are available and their data are provided just for short periods of time. Numéro de notice : A2019-609 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01297-z date de publication en ligne : 01/10/2019 En ligne : https://doi.org/10.1007/s00190-019-01297-z Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94792 [article]

Is the Jason-2 DORIS oscillator also affected by the South Atlantic Anomaly? / Pascal Willis in Advances in space research, vol 58 n° 12 (15 December 2016)  

Public [article]  inAdvances in space research > vol 58 n° 12 (15 December 2016) . - pp 2617 - 2627 Titre : Is the Jason-2 DORIS oscillator also affected by the South Atlantic Anomaly? Type de document : Article/Communication Auteurs : Pascal Willis , Auteur ; Michael B. Heflin, Auteur ; Bruce J. Haines, Auteur ; Yoaz E. Bar-Sever, Auteur ; Willy I. Bertiger, Auteur ; Mioara Mandea, Auteur Année de publication : 2016 Article en page(s) : pp 2617 - 2627 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] anomalie de Bouguer [Termes descripteurs IGN] Atlantique Sud [Termes descripteurs IGN] co-positionnement [Termes descripteurs IGN] données DORIS [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] Jason [Termes descripteurs IGN] oscillateur [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] résidu [Termes descripteurs IGN] série temporelle [Termes descripteurs IGN] station permanente Résumé : (auteur) We analyzed time series of daily DORIS and GPS station coordinate estimates derived from Precise Point Positioning (PPP). The DORIS coordinates were estimated using Jason-2 precise orbits based on GPS data only, implying that the station positions from the two techniques are expressed in the same GPS-based terrestrial reference frame. Comparisons of 3-D vectors of such co-located stations show systematic biases in position around South America when compared to local geodetic ties. We conclude that these results could be explained by a sensitivity of the Jason-2/DORIS oscillator to radiation when the satellite passes over the South Atlantic Anomaly (SAA). The effect for Jason-2 manifests mainly as an offset in station coordinates, though there is also evidence of a drift at the start of the mission that diminishes in time. This contrasts with the experience on Jason-1, wherein large, persistent drifts were observed for stations in this same (SAA) region. The spurious drift is much (∼90%) smaller for Jason-2, which may be attributable to the steps taken prior to launch to harden the oscillator. Analysis of DORIS Doppler residuals may indicate some small degradation after 2009 for these stations. Numéro de notice : A2016--178 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2016.09.015 date de publication en ligne : 21/09/2016 En ligne : https://doi.org/10.1016/j.asr.2016.09.015 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91806 [article]

Identifying a low-frequency oscillation in Galileo IOV pseudorange rates / Daniele Borio in GPS solutions, vol 20 n° 3 (July 2016)  

Public [article]  inGPS solutions > vol 20 n° 3 (July 2016) . - pp 363 - 372 Titre : Identifying a low-frequency oscillation in Galileo IOV pseudorange rates Type de document : Article/Communication Auteurs : Daniele Borio, Auteur ; Ciro Gioia, Auteur ; Neil Mitchison, Auteur Année de publication : 2016 Article en page(s) : pp 363 - 372 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] étalonnage en vol [Termes descripteurs IGN] Galileo [Termes descripteurs IGN] horloge atomique [Termes descripteurs IGN] mesurage de pseudo-distance [Termes descripteurs IGN] oscillateur [Termes descripteurs IGN] performance [Termes descripteurs IGN] vitesse Résumé : (Auteur) Galileo, the European global navigation satellite system, is in its in-orbit validation phase and the four satellites which have been available for some months now have allowed a preliminary analysis of the system performance. Previous studies have showed that Galileo will be able to provide pseudorange measurements more accurate than those provided by GPS. However, a similar improvement was not found for pseudorange rate observations in the velocity domain. This fact stimulated additional analysis of the velocity domain, and, in particular, an unintended oscillatory component was identified as the main error source in the velocity solution. The magnitude of such oscillation is less than 10 cm/s, and its period is in the order of few minutes. A methodology was developed to identify oscillatory components in the Galileo IOV pseudorange rate observables, and it was verified that the measurements from Galileo IOV PFM and Galileo IOV FM2 are affected by a small oscillatory disturbance. This disturbance stems from the architecture adopted for combining the frequency references provided by the two active clocks present in the Galileo satellites. The issue has been solved in Galileo IOV FM3 and Galileo IOV FM4, and the oscillatory component has been eliminated. We also propose a methodology for removing this unwanted component from the final velocity solution and for determining the performance that Galileo will be able to achieve. The analysis shows that Galileo velocity solution will provide a root-mean-square error of about 8 cm/s even in the limited geometry conditions achieved using only four satellites. This shows the potential of Galileo also in the determination of user velocity. Numéro de notice : A2016-630 Thématique : POSITIONNEMENT Nature : Article En ligne : http://dx.doi.org/10.1007/s10291-015-0443-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81833 [article]

Optimizing Indoor GPS performance: receiver frequency standards / L.D. Vittorini in GPS world, vol 14 n° 11 (November 2003)

Public [article]  inGPS world > vol 14 n° 11 (November 2003) . - pp 40 - 48 Titre : Optimizing Indoor GPS performance: receiver frequency standards Type de document : Article/Communication Auteurs : L.D. Vittorini, Auteur ; et al., Auteur Année de publication : 2003 Article en page(s) : pp 40 - 48 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] oscillateur [Termes descripteurs IGN] positionnement en intérieur [Termes descripteurs IGN] positionnement par GPS [Termes descripteurs IGN] récepteur GPS Résumé : (Editeur) While orbiting GPS satellites use atomic frequency standards to generate the ranging sig-nals, most GPS receivers can determine position using only a simple frequency standard: a quartz crystal oscillator. Mass-produced quartz crystal oscillators are found in virtually every piece of electronic equipment, from wristwatches to GPS receivers. Oscillators contribute only a fraction of a receiver's manufacturing cost and have helped reduce consumer cost for a basic receiver to less than $100.The common consumer GPS product sold today, however, will generally not function indoors and will have difficulty dealing with signal blockage from buildings and foliage. In recent years, engineers have developed receivers that will perform satisfactorily even with multipath-corrupted and severely attenuated signals such as those found indoors. This month's column examines the quartz crystal oscillator's role as a frequency standard in a GPS receiver and how certain characteristics of these mass-produced devices can limit per-formance for indoor use. Copyright Advanstar Communications Numéro de notice : A2003-439 Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26518 [article]

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Instrument of GRACE: GPS augments gravity measurements / C. Dunn in GPS world, vol 14 n° 2 (February 2003)

Public [article]  inGPS world > vol 14 n° 2 (February 2003) . - pp 16 - 28 Titre : Instrument of GRACE: GPS augments gravity measurements Type de document : Article/Communication Auteurs : C. Dunn, Auteur ; et al., Auteur Année de publication : 2003 Article en page(s) : pp 16 - 28 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] champ de pesanteur terrestre [Termes descripteurs IGN] géoïde altimétrique [Termes descripteurs IGN] géoïde terrestre [Termes descripteurs IGN] GRACE [Termes descripteurs IGN] gravimétrie aérienne [Termes descripteurs IGN] instrument de mesure [Termes descripteurs IGN] levé gravimétrique [Termes descripteurs IGN] nivellement par GPS [Termes descripteurs IGN] orbitographie [Termes descripteurs IGN] oscillateur [Termes descripteurs IGN] pesanteur terrestre [Termes descripteurs IGN] précision centimétrique Résumé : (Editeur) Using GPS timing to calibrate a microwave ranging system, the GRACE twins will improve knowledge of the Earth's geoid height from the current meter level. In doing so, the system determines the 200-kilometer separation between the two orbiting satellite to the width of a human blood cell. Copyright Questex Media Group Inc Numéro de notice : A2003-081 Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22377 [article]

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Technical documentation for shipboard receivers / National security industrial association of usa (1967)

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