Centre de documentation
scientifique

Evaluation of multipath mitigation performance using signal-to-noise ratio (SNR) based signal selection methods / Valanon Uaratanawong in Journal of applied geodesy, vol 15 n° 1 (January 2021)  

Public [article]  inJournal of applied geodesy > vol 15 n° 1 (January 2021) . - pp 75 - 85 Titre : Evaluation of multipath mitigation performance using signal-to-noise ratio (SNR) based signal selection methods Type de document : Article/Communication Auteurs : Valanon Uaratanawong, Auteur ; Chalermchon Satirapod, Auteur ; Toshiaki Tsujii, Auteur Année de publication : 2021 Article en page(s) : pp 75 - 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] classification par nuées dynamiques [Termes IGN] correction du trajet multiple [Termes IGN] positionnement statique [Termes IGN] précision du positionnement [Termes IGN] qualité du signal [Termes IGN] rapport signal sur bruit Résumé : (auteur) Satellite signal strength sometimes decreases when multipath exists. This effect reduces signal quality and can lead to a large static positioning error, even the survey-grade receivers are used. Three signal selection methods based on signal-to-noise ratio (SNR) measurements were proposed. The first was the conventional method, based on elevation-dependent average SNR, the second used a moving average of SNR fluctuation and the third method used NLOS exclusion based on SNR residual clustering by the K-means algorithm. To evaluate the positioning accuracy improvement, the static 1 Hz single-point positioning (SPP) test was performed in real-time in two different multipath environments using both dual and quad- constellation GNSS receivers. Trimble and CHC receivers were used at each point to examine the effect on each measurement. Results indicated that the three proposed methods mainly reduced multipath error in horizontal direction compared with the normal SPP. Numéro de notice : A2021-046 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2020-0045 Date de publication en ligne : 09/12/2020 En ligne : https://doi.org/10.1515/jag-2020-0045 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96774 [article]

First AGPS - now BGPS: instantaneous precise positioning anywhere / I. Petrovski in GPS world, vol 19 n° 11 (November 2008)

Public [article]  inGPS world > vol 19 n° 11 (November 2008) . - pp 42 - 48 Titre : First AGPS - now BGPS: instantaneous precise positioning anywhere Type de document : Article/Communication Auteurs : I. Petrovski, Auteur ; H. Hojo, Auteur ; Toshiaki Tsujii, Auteur Année de publication : 2008 Article en page(s) : pp 42 - 48 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] GPS assisté pour la navigation (technologies) [Termes IGN] lever mobile [Termes IGN] positionnement cinématique en temps réel [Termes IGN] réseau géodésique [Termes IGN] signal GPS Résumé : (Editeur) Instant GPS positioning appears to be at hand. For better or worse, we live in fast communications, and fast cars, and have come to expect instant responses when we want something. [...] After switching on our receiver, we typically have to wait for some time before we can start navigating. This time to first fix (TTFF) depends on the quality of the received signals and the age of the receiver's stored almanac and ephemerides used to determine the positions of the satellites. It's also affected by how well the receiver knows the exact time. So there are several kinds of TTFF. If a receiver has no knowledge of its last position, doesn't know the approximate time, and has no almanac, it starts searching for signals blindly. This called a cold start. Depending on signal quality and design to the receiver, it can take anywhere from 60 seconds to 12 minutes or more before the receiver acquires signals, obtains ephemeris data, measures pseudoranges and gets its first position fix. If the receiver knows the approximate time as well as its approximate position and has a recent almanac but not a current ephemeris, it can produce a position fix within about 30 seconds or so after it is switched on - the time required to receive orbit and clock data from the tracked satellites. This is called a warm start. A hot start occurs when a receiver is powered on with a current ephemeris (received within the past four hours). It can take up to 6 seconds or more before the first fix as the receiver must typically acquire times marks from the satellite navigation messages to resolve the pseudorange ambiguities. Assisted GPS, or AGPS, can reduce TTFF by suplying current ephemeris data and accurate time over a mobile phone network. In some situations, TTFF can be reduced to just a second or two. However, the receiver does need to be connected to an AGPS network and so cannot operate autonomously. Enter BGPS. In this month's column we learn about an innovative approach that can produce accurate fist fixes within one second and without a network connection ? Copyright Questex Media Group Inc Numéro de notice : A2008-449 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29518 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
067-08111	RAB	Revue	Centre de documentation	En réserve L003	Disponible