Search results for "GNSS"
showing 10 items of 88 documents
Monitoring Water Surface and Level of a Reservoir Using Different Remote Sensing Approaches and Comparison with Dam Displacements Evaluated via GNSS
2018
Remote sensing allowed monitoring the reservoir water level by estimating its surface extension. Surface extension has been estimated using different approaches, employing both optical (Landsat 5 TM, Landsat 7 ETM+ SLC-Off, Landsat 8 OLI-TIRS and ASTER images) and Synthetic Aperture Radar (SAR) images (Cosmo SkyMed and TerraSAR-X). Images were characterized by different acquisition modes, geometric and spectral resolutions, allowing the evaluation of alternative and/or complementary techniques. For each kind of image, two techniques have been tested: The first based on an unsupervised classification and suitable to automate the process, the second based on visual matching with contour lines…
Precipitable water vapour content from ESR/SKYNET sun-sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe
2018
The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration par…
First considerations on post processing kinematic GNSS data during a geophysical oceanographic cruise
2021
<p class="Abstract">Differential GNSS positioning on vessels is of considerable interest in various fields of application as navigation aids, precision positioning for geophysical surveys or sampling purposes especially when high resolution bathymetric surveys are conducted. However ship positioning must be considered a kinematic survey with all the associated problems. The possibility of using high-precision differential GNSS receivers in navigation is of increasing interest, also due to the very recent availability of low-cost differential receivers that may soon replace classic navigation ones based on the less accurate point positioning technique. The availability of greater plano…
A Kalman filter single point positioning for maritime applications using a smartphone
2020
Different positioning techniques have been largely adopted for maritime applications that require high accuracy kinematic positioning. The main objective of the paper is the performance assessment of a Single Point Positioning algorithm (SPP), with a Kalman filter (KF) estimator, adapted for maritime applications. The KF has been chosen as estimation technique due to the ability to consider both the state vector dynamic and the measurements. Particularly, in order to compute an accurate vertical component of the position, suitable for maritime applications, the KF settings have been modified by tuning the covariance matrix of the process noise. The algorithm is developed in Matlab environme…
Global Navigation Satellite Systems And Services
2008
This chapter introduces the concept of Satellite Navigation in the context of space infrastructures and technologies that can contribute for improvement of life on Earth. It includes a review of the motivations for developing a satellite navigation system, and the applications and services these systems have in daily life. Furthermore, currently existing Global Navigation Satellite Systems (GPS and GLONASS) and other GNSS systems under development (GALILEO) are described from different perspectives: from the technical and architectural aspects to the ways chosen to finance their development and operations. To round up this chapter, an analysis of the expected trends in GNSS systems is prese…
GeoNET: WebGIS of a GNSS Permanent Network
2009
In Sicily, from 2005 to 2007, a research group at the Dipartimento di Rappresentazione, DIRAP (University of Palermo) has realized a Global Navigation Satellite System (GNSS) network for real time positioning (Network Real Time Kinematic –NRTK), activity founded by “Minister of Instruction, University and Scientific Research” (MIUR) as “National Interest Research Program” PRIN2005 entitled "Networks of permanent GPS stations for the survey in real time control and use of emergency". The data-base contains different kind of information both general on the network and positional. Positional information can be useful for two types of survey applications: static survey with post-processing of d…
Compensazione Geodetica della rete siciliana UNIPA-NetGeo
2012
Come è noto un servizio di posizionamento GNSS materializza un sistema di riferimento e distribuisce all’utenza che opera nel settore geodetico dati, prodotti e stime delle coordinate nel medesimo sistema. Per questo motivo si rende necessaria un accurata e continua stima delle coordinate, delle stazioni permanenti che compongono la rete, effettuata attraverso opportuni processi di compensazione. A tal proposito, considerato il notevole incremento delle stazioni permanenti presenti nel territorio Italiano, l’inquadramento geodetico delle reti regionali dovrebbe essere effettuato nel sistema di riferimento globale, per non incorrere nelle notevoli differenze di coordinate stimate tra le reti…
Percorsi nel "Grande Cretto" di Alberto Burri in Gibellina Vecchia (TP)
2013
MONITORAGGIO DI OPERE STRATEGICHE MEDIANTE TECNICHE SATELLITARI: IL CASO STUDIO DELLA DIGA “CASTELLO SUL FIUME MAGAZZOLO”
2017
Il Global Navigation Satellite System (GNSS) e il telerilevamento sono stati utilizzati per determinare la relazione tra le deformazioni di una diga di terra e le variazioni di superficie e livello di invaso, durante il periodo di un anno. L’utilizzo di un ricevitore posto sul coronamento della diga e di una stazione permanente attivi durante l’arco della giornata ha permesso la determinazione della serie temporale degli spostamenti dell’opera nel periodo analizzato, riferiti ad un sistema di riferimento locale della diga. La componente ortogonale al coronamento è stata successivamente posta in relazione con le forze di natura idraulica che agiscono sull’opera. Per la determinazione dei liv…
Digital zenith camera for vertical deflection determination
2012
Recent accomplishments in advancement of accurate astrometric reference star catalogues, development of digital imaging technology, high accuracy tiltmeter technology, and geocentric coordinate availability provided by GNSS, have made possible accurate, fast and automated determination of vertical deflections using astrometric methods. Zenith cameras for this kind of measurements have been developed or are being developed by several research groups. The paper describes a research project by Institute of Geodesy and Geoinformation, intended to design a portable digital zenith camera for vertical deflection determination with 0.1” expected accuracy. Camera components are described, proposed d…