Search results for "Gnss"
showing 10 items of 88 documents
Phase lock loop false lock avoidance in presence of global navigation satellite system signal
2009
In this paper we analyse the operation of a fully digital Phase Lock Loop (PLL) in a false lock regime, using real data. The issue has been noticed while we were testing performance of our software receiver in a moving user scenario. While the phenomenon of false lock has been described in other papers about PLLs, our intent is to describe a practical, and in our opinion interesting, issue we encountered and how we got over it.
A Review on Multi-GNSS for Earth Observation and Emerging Applications
2022
Global Navigation Satellite System (GNSS) has drawn the attention of scientists and users all over the world for its wide-ranging Earth observations and applications. Since the end of May 2022, more than 130 satellites are available for fully global operational satellite navigation systems, such as BeiDou Navigation Satellite System (BDS), Galileo, GLONASS and GPS, which have been widely used in positioning, navigation, and timing (PNT), e.g., precise orbit determination and location-based services. Recently, the refracted, reflected, and scattered signals from GNSS can remotely sense the Earth’s surface and atmosphere with potential applications in environmental remote sensing. In this pap…
An integrated geodetic and InSAR technique for the monitoring and detection of active faulting in southwestern Sicily
2020
We present the results of the analysis of GNSS (Global Navigation Satellite System) and InSAR (Interferometric synthetic-aperture radar) data collected in the frame of a project financed by the “Struttura Terremoti” of INGV (Istituto Nazionale di Geofisica e Vulcanologia). Combined investigations pointed out for potential seismogenic sources for destructive earthquakes recorded in southwestern Sicily, including the 1968 Belice earthquake sequence and that supposed to have destroyed the Greek city of Selinunte which, according to geoarcheological data experienced two earthquakes in historical times. Our approach is aimed to evaluate the current deformation rate in SW Sicily and to improve th…
Investigating effects in GNSS station coordinate time series
2014
The vertical and horizontal displacements of the Earth can be measured to a high degree of precision using GNSS. Time series of Latvian GNSS station positions of both the EUPOS®-Riga and LatPos networks have been developed at the Institute of Geodesy and Geoinformation of the University of Latvia (LU GGI). In this study the main focus is made on the noise analysis of the obtained time series and site displacement identification. The results of time series have been analysed and distinctive behaviour of EUPOS®-Riga and LatPos station coordinate changes have been identified. The possible dependences of GNSS station coordinate distribution on EPN station problems, seismic activity of some area…
Development of the One Centimeter Accuracy Geoid Model of Latvia for GNSS Measurements
2015
There is an urgent necessity for a highly accurate and reliable geoid model to enable prompt determination of normal height with the use of GNSS coordinate determination due to the high precision requirements in geodesy, building and high precision road construction development. Additionally, the Latvian height system is in the process of transition from BAS- 77 (Baltic Height System) to EVRS2007 system. The accuracy of the geoid model must approach the precision of about ~1 cm looking forward to the Baltic Rail and other big projects. The use of all the available and verified data sources is planned, including the use of enlarged set of GNSS/levelling data, gravimetric measurement data and…
The Near Real Time Ionospheric Model of Latvia
2015
A highly accurate ionosphere model is necessary to enable a fast and reliable coordinate determination with GNSS in real time. It is a partially ionized atmospheric region ranging up to 1,000 km height, affected by spatial variations, space weather, seasonal and solar cycle dependence. New approaches and algorithms of modelling techniques are sought to provide better solutions in the territory of Latvia. Ionospheric TEC value has large differences in Western Latvia and Eastern Latvia. Actual ionospheric map should be calculated and delivered to the surveyors near real time and published on the WEB. Delivering actual map to rover GNSS devices in a field will provide the surveyors with ionosp…
Rilievo ed elaborazione di dati laser acquisiti con sistemi MMS in un parco urbano
2013
Questo articolo riassume l'esperienza acquisita tra il 2012 e il 2013 dal Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale e dei Materiali dell'Università degli Studi di Palermo per l'indagine integrata del Parco Ninni Cassarà a Palermo, Italia, e la successiva sperimentazione di metodi, strumenti e tecniche basate su ricerche in corso, per quanto riguarda l'acquisizione e l'elaborazione dei dati GNSS e laser Scanner. Il lavoro è stato affrontato al fine di selezionare le tecniche meno costose e veloci da applicare in fase di acquisizione. Dopo la prima monumentazione di sedici punti di controllo distribuiti all'interno del sito e rilevati con ricevitori GNSS, la è stata pianific…
Distributed GNSS-Based Time Synchronization and Applications
2016
The paper deals with synchronization standards, applications and challenges in the modern packet switched telecommunication networks. In recent years, the number of time-dependent services and systems only increases with the development of such areas as Internet of Things (IoT), industrial Internet, remote automation and robotics, precise positioning etc. In the paper, these emerging applications are discussed. An alternative way to the traditional centralized synchronization infrastructure is proposed. Compact and low-priced devices equipped with a Global Navigation Satellite System (GNSS) receiver and a reliable internal clock can be installed specifically in the places where they are nee…