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Improved wavelet neural network based on change rate to predict satellite clock bias / Xu Wang in Survey review, vol 52 n° 372 (May 2020)  

Public [article]  inSurvey review > vol 52 n° 372 (May 2020) Titre : Improved wavelet neural network based on change rate to predict satellite clock bias Type de document : Article/Communication Auteurs : Xu Wang, Auteur ; Hongzhou Chai, Auteur ; Chang Wang, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] courbe de Gauss [Termes descripteurs IGN] erreur systématique interfréquence d'horloge [Termes descripteurs IGN] estimation de précision [Termes descripteurs IGN] ondelette [Termes descripteurs IGN] ondelette de Shannon [Termes descripteurs IGN] prévision [Termes descripteurs IGN] réseau neuronal artificiel Résumé : (auteur) To develop a high-accuracy method for predicting SCB based on the analysis of the shortcomings of the wavelet neural network (WNN) model, an improved WNN model to predict SCB is proposed herein. The activation function of the WNN is constructed by combining the advantages of Shannon and Gauss ‘window’ functions to improve the WNN. Finally, the improved WNN model is used to predict SCB. The results show that the proposed model has the highest prediction accuracy, stability, and robustness. Moreover, it effectively predicts long-time SCB data. Therefore, the proposed model can predict SCB with high accuracy. Numéro de notice : A2020-289 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2020.1758999 date de publication en ligne : 24/05/2020 En ligne : https://doi.org/10.1080/00396265.2020.1758999 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95117 [article]

Performance analysis of BDS/GPS precise point positioning with undifferenced ambiguity resolution / Min Wang in Advances in space research, vol 60 n° 12 (15 December 2017)  

Public [article]  inAdvances in space research > vol 60 n° 12 (15 December 2017) . - pp 2581 - 2595 Titre : Performance analysis of BDS/GPS precise point positioning with undifferenced ambiguity resolution Type de document : Article/Communication Auteurs : Min Wang, Auteur ; Hongzhou Chai, Auteur ; Yu Li, Auteur Année de publication : 2017 Article en page(s) : pp 2581 - 2595 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes descripteurs IGN] données BeiDou [Termes descripteurs IGN] données GPS [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] méthode des moindres carrés [Termes descripteurs IGN] positionnement ponctuel précis [Termes descripteurs IGN] résolution d'ambiguïté Résumé : (auteur) The undifferenced ambiguity resolution has been proved to be an effective method to shorten the initialization of precise point positioning (PPP) solution and improve the positioning accuracy. Several techniques were proposed for undifferenced ambiguity resolution with GPS observations. However, for BeiDou navigation satellite system (BDS), the satellite-induced variation in pseudorange observation changes the characteristics of Melbourne-Wűbbena (MW) combination observation, which leads to unacceptably low fixing rate of undifferenced ambiguity. Besides, the characteristics of satellite-induced variations in BDS observations vary with orbit type of satellite, which should be considered in correction effort. In this paper, the BDS fractional cycle biases (FCBs) are estimated with least-squares estimation method using the float undifferenced ambiguity collected from the network of reference stations. Based on the analysis of weekly stability of widelane FCBs and the distribution of fractional ambiguity parts, it is proven that the satellite-induced variation correction is necessary for the FCB estimation for IGSO and MEO satellites. Contaminated by relatively large orbit error, the ambiguities of GEO satellites should be skipped for ambiguity resolution attempt. Resolving BDS ambiguities in BDS/GPS combined PPP could significantly shorten the time needed for the first correct ambiguity resolution (FCAR). The experiment results of static PPP demonstrate that 90.6% of all sessions accomplish FCAR within 1350 s with only GPS observations. Meanwhile, by adding BDS ambiguities to the subset of ambiguity resolution, 91.9% of all sessions accomplish FCAR with only 870 s. Numéro de notice : A2017-752 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2017.01.045 En ligne : https://doi.org/10.1016/j.asr.2017.01.045 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89037 [article]