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Wide-area ionospheric delay model for GNSS users in middle- and low-magnetic-latitude regions / An-Lin Tao in GPS solutions, vol 20 n° 1 (January 2016)  

Public [article]  inGPS solutions > vol 20 n° 1 (January 2016) . - pp 9 - 21 Titre : Wide-area ionospheric delay model for GNSS users in middle- and low-magnetic-latitude regions Type de document : Article/Communication Auteurs : An-Lin Tao, Auteur ; Shau-Shiun Jan, Auteur Année de publication : 2016 Article en page(s) : pp 9 - 21 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse comparative [Termes IGN] Asie (géographie politique) [Termes IGN] modèle ionosphérique [Termes IGN] Quasi-Zenith Satellite System [Termes IGN] retard ionosphèrique [Termes IGN] station permanente [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) A useful ionospheric delay model to compensate for the effect of ionospheric error on GNSS service over continent-wide areas or oceans is the Satellite-Based Augmentation System’s wide-area thin-shell planar fit ionospheric grid model. In order to implement a proper wide-area ionospheric delay model in the Asia-Pacific region to reflect the variation introduced by local ionospheric activity, the present study develops a proper ionospheric delay model to correct ionospheric error in middle- and low-magnetic-latitude regions. Specifically, the proposed ionospheric delay model uses several dual-frequency GNSS reference stations distributed in Taiwan, South Korea, Japan, and China as grid points in place of the conventional grid points generated by ionospheric pierce points. The ionospheric delays observed at the reference stations are processed and provided to the user, who can then construct the ionospheric delay model using weighted least squares with the distances between the user and the stations as weights. This proposed ionospheric delay model lowers the computation load by eliminating the conversion of delays at the ionospheric pierce points to those at the grid points and provides good descriptions of dynamic variations due to the ionospheric activities. Also, a simplified model is developed to further reduce its computation load while providing almost the same service as that of the original proposed model. A selection mechanism between the original proposed model and its simplified version is developed as well. The details of the proposed ionospheric delay model are explained, and experiments conducted using data collected from the reference stations in the Asia-Pacific region are presented. The effectiveness of the proposed model is validated by comparison with the conventional wide-area thin-shell planar fit ionospheric grid model provided by the Japanese Multi-functional Satellite Augmentation System under both nominal and disturbed ionospheric conditions. Numéro de notice : A2016-601 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0435-z En ligne : http://dx.doi.org/10.1007/s10291-014-0435-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81787 [article]

Tight integration of ambiguity-fixed PPP and INS: model description and initial results / Shuai Liu in GPS solutions, vol 20 n° 1 (January 2016)  

Public [article]  inGPS solutions > vol 20 n° 1 (January 2016) . - pp 39 - 49 Titre : Tight integration of ambiguity-fixed PPP and INS: model description and initial results Type de document : Article/Communication Auteurs : Shuai Liu, Auteur ; Fuping Sun, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 39 - 49 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] ambiguïté entière [Termes IGN] centrale inertielle [Termes IGN] couplage GNSS-INS [Termes IGN] positionnement ponctuel précis [Termes IGN] précision centimétrique [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) The traditional PPP/INS system is still not used as widely as the DGNSS/INS system in precise applications, although no local reference stations are required. The main reason that prevents its use is that the traditional PPP/INS system is based on the float ambiguity solution, which leads to long convergence period and unstable positioning accuracy. We propose a tightly coupled ambiguity-fixed PPP/INS integration. First, the derivation of the observation model of the ambiguity-fixed PPP at the single-difference level using integer phase clock products from Center National d’Etudes Spatiales is presented in detail. Then the inertial navigation system model is presented. With these two models, the tightly coupled model of the PPP/INS integration is established. Finally, two carborne tests are used to evaluate the performance of the tight integration of ambiguity-fixed PPP and INS. Experimental results indicate that the proposed ambiguity-fixed PPP/INS integration is able to reach stable centimeter-level positioning after the first-fixed solution and its overall performance is comparable to that of the DGNSS/INS integration, and rapid re-convergence and re-fixing are achievable after a short period of GNSS outage for the PPP/INS integration. Numéro de notice : A2016-602 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0464-2 En ligne : http://dx.doi.org/10.1007/s10291-015-0464-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81788 [article]

Adaptive GPS/INS integration for relative navigation / Je Young Lee in GPS solutions, vol 20 n° 1 (January 2016)  

Public [article]  inGPS solutions > vol 20 n° 1 (January 2016) . - pp 63 - 75 Titre : Adaptive GPS/INS integration for relative navigation Type de document : Article/Communication Auteurs : Je Young Lee, Auteur ; Hee Sung Kim, Auteur ; Kwang Ho Choi, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 63 - 75 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] covariance [Termes IGN] filtre de Kalman [Termes IGN] GPS-INS [Termes IGN] intégration de données [Termes IGN] navigation Résumé : (Auteur) Relative navigation based on GPS receivers and inertial measurement units is required in many applications including formation flying, collision avoidance, cooperative positioning, and accident monitoring. Since sensors are mounted on different vehicles which are moving independently, sensor errors are more variable in relative navigation than in single-vehicle navigation due to different vehicle dynamics and signal environments. In order to improve the robustness against sensor error variability in relative navigation, we present an efficient adaptive GPS/INS integration method. In the proposed method, the covariances of GPS and inertial measurements are estimated separately by the innovations of two fundamentally different filters. One is the position-domain carrier-smoothed-code filter and the other is the velocity-aided Kalman filter. By the proposed two-filter adaptive estimation method, the covariance estimation of the two sensors can be isolated effectively since each filter estimates its own measurement noise. Simulation and experimental results demonstrate that the proposed method improves relative navigation accuracy by appropriate noise covariance estimation. Numéro de notice : A2016-603 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0446-4 En ligne : http://dx.doi.org/10.1007/s10291-015-0446-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81801 [article]

Improving MEMS-IMU/GPS integrated systems for land vehicle navigation applications / S. Sasani in GPS solutions, vol 20 n° 1 (January 2016)  

Public [article]  inGPS solutions > vol 20 n° 1 (January 2016) . - pp 89 - 100 Titre : Improving MEMS-IMU/GPS integrated systems for land vehicle navigation applications Type de document : Article/Communication Auteurs : S. Sasani, Auteur ; Jamal Asgari, Auteur ; Ali Reza Amiri-Simkooei, Auteur Année de publication : 2016 Article en page(s) : pp 89 - 100 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] attitude and heading reference system AHRS [Termes IGN] filtre de Kalman [Termes IGN] GPS-INS [Termes IGN] microsystème électromécanique [Termes IGN] orientation de véhicule Résumé : (Auteur) The cost of inertial navigation systems (INS) has decreased significantly during recent years using micro-electro-mechanical system technology in production of inertial measurement units (IMUs). However, these IMUs do not provide the accuracy and stability of their classical mechanical counterparts which limit their applications. Hence, the error control of such systems is of the great importance which is achievable using external information via an appropriate fusion algorithm. Traditionally, this external information can be derived from global positioning system (GPS). But it is well known that GPS data availability and accuracy are vulnerable to signal-degrading circumstances and satellite visibility. We introduce a standalone attitude and heading reference system (AHRS) algorithm which employs the IMU and magnetometers data in an averaging manner. The averaging method is different from a simple smoothing procedure, since it takes the rotations of the platform (during the averaging interval) into account. The proposed AHRS solution is further used to provide additional attitude updates with adaptive noise variances for the integrated INS/GPS system during GPS outages via a refined loosely coupled filtering procedure, making the error growth well restrained. Functionality of the algorithm has been assessed via a field test. The results indicate that the proposed procedure outperforms the traditional integration scheme in different situations, while the latter almost loses track of the movements of the vehicle after 60-second GPS outages. Numéro de notice : A2016-604 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0471-3 En ligne : http://dx.doi.org/10.1007/s10291-015-0471-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81803 [article]

Effectiveness of observation-domain sidereal filtering for GPS precise point positioning / Christopher Atkins in GPS solutions, vol 20 n° 1 (January 2016)  

Public [article]  inGPS solutions > vol 20 n° 1 (January 2016) . - pp 111 - 122 Titre : Effectiveness of observation-domain sidereal filtering for GPS precise point positioning Type de document : Article/Communication Auteurs : Christopher Atkins, Auteur ; Marek Ziebart, Auteur Année de publication : 2016 Article en page(s) : pp 111 - 122 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] correction du trajet multiple [Termes IGN] phase [Termes IGN] positionnement ponctuel précis [Termes IGN] propagation ionosphérique [Termes IGN] séisme [Termes IGN] variance d'Allan [Vedettes matières IGN] Traitement de données GNSS Résumé : (Auteur) Sidereal filtering is a technique used to reduce errors caused by multipath in the positioning of static receivers via the Global Positioning System (GPS). It relies upon the receiver and its surrounding environment remaining static from one day to the next and takes advantage of the approximately sidereal repeat time of the GPS constellation geometry. The repeating multipath error can thus be identified, usually in the position domain, and largely removed from the following day. We describe an observation-domain sidereal filter algorithm that operates on undifferenced ionospheric-free GPS carrier phase measurements to reduce errors caused by multipath. It is applied in the context of high-rate (1 Hz) precise point positioning of a static receiver. An observation-domain sidereal filter (ODSF) is able to account for the slightly different repeat times of each GPS satellite, unlike a position-domain sidereal filter (PDSF), and can hence be more effective at reducing high-frequency multipath error. Using 8-h long datasets of GPS measurements from two different receivers with different antenna types and contrasting environments, the ODSF algorithm is shown overall to yield a position time series 5–10 % more stable, in terms of Allan deviation, than a PDSF over nearly all time intervals below about 200 s in length. This may be particularly useful for earthquake and tsunami early warning systems where the accurate measurement of small displacements of the ground over the period of just a few minutes is crucial. However, the sidereal filters are also applied to a third dataset during which two short episodes of particularly high-frequency multipath error were identified. These two periods are analyzed in detail and illustrate the limitations of using sidereal filters with important implications for other methods of correcting for multipath at the observation level. Numéro de notice : A2016-605 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0473-1 En ligne : http://dx.doi.org/10.1007/s10291-015-0473-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81806 [article]