1,721,011 research outputs found
goGPS: open source software for enhancing the accuracy of low-cost receivers by single-frequency relative kinematic positioning
No full textgoGPS is a free and open source satellite positioning software package aiming to provide a collaborative platform for research and teaching purposes. It was first published in 2009 and since then several related projects are on-going. Its objective is the investigation of strategies for enhancing the accuracy of low-cost single-frequency GPS receivers, mainly by relative positioning with respect to a base station and by a tailored extended Kalman filter working directly on code and phase observations. In this paper, the positioning algorithms implemented in goGPS are presented, emphasizing the modularity of the software design; two specific strategies to support the navigation with low-cost receivers are also proposed and discussed, namely an empirical observation weighting function calibrated on the receiver signal-to-noise ratio and the inclusion of height information from a digital terrain model as an additional observation in the Kalman filter. The former is crucial when working with high-sensitivity receivers, while the latter can significantly improve the positioning in the vertical direction. The overall goGPS positioning accuracy is assessed by comparison with a dual-frequency receiver and with the positioning computed by a standard low-cost receiver. The benefits of the calibrated weighting function and the digital terrain model are investigated by an experiment in a dense urban environment. It comes out that the use of goGPS and low-cost receivers leads to results comparable with those obtained by higher level receivers; goGPS has good performances also in a dense urban environment, where its additional features play an important role
Uncovering a masterpiece of Roman engineering: The project of Via Appia between Colle Pardo and Terracina
No full textVia Appia, built around 312 BC, is an engineering masterpiece, its most striking feature being the segment between Colle Pardo and Terracina, which goes “straight” for about 61 km. We investigate this segment by GPS techniques: results lead to uncover that the original project of the road was based on a complex interplay between geometry and astronomy. The project was indeed carried out with the help of an orthogonal centuriation grid, with all probabilities starting from a node located at the south easternmost point of the grid itself. The road however does not run along the grid's diagonal: it was orientated astronomically to the setting of the star Castor at the time of construction. Since the Gemini twins were patrons of the Roman army, the project turns out to be a work entertained for both practical and symbolic reasons, during a key moment of the Roman history
High-precision GPS survey of Via Appia: Archaeoastronomy-related aspects
Full text linkVia Appia was built by the Romans around 312 BCE to connect Rome with Capua during the Samnite wars. The road is an astonishing engineering masterpiece. In particular, the segment which runs from Collepardo to Terracina – 61 km long – is renowned for being virtually straight; however this “straightness” was never investigated quantitatively. As a consequence, the techniques used by the ancient surveyors and their scope – whether it was only practical, or also symbolic – remain obscure. We report here a high-precision GPS survey of the road, performed with a u-blox receiver and further checked with a dual frequency receiver. We give a detailed analysis of the methods used and of the errors, which are shown to be less than 6’. To our knowledge it is the first time that such a long ancient manufactured structure has been surveyed with such a high accuracy. The results lead us to conclude that astronomy was certainly used in the construction of the road and in that of the associated grid, oriented to the setting of the star Castor and to the cardinal points respectively
Experimental study on low-cost satellite-based geodetic monitoring over short baselines
Full text linkThe use of geodetic techniques, in particular of the global positioning system (GPS), or other global navigation satellite systems (GNSS), for monitoring different kinds of deformations is a common practice. This is typically performed by setting a network of geodetic GPS/GNSS receivers, allowing accuracies in the order of millimeters. The use of lower-cost devices has been recently studied, showing that good results can be achieved. In this paper, the impact of the software used for the data analysis is also investigated to verify whether a fully low-cost monitoring system, i.e., both hardware and software, can be set up. This is done by performing a series of relative positioning experiments in which data are processed by different software packages. The main result is that by using a low-cost u-blox EVK-6T GPS receiver and analyzing its data with free and open-source software, movements of the order of a few millimeters can be detected when a short baseline with daily solutions is used
Geometry and astronomy in the project of ancient straight roads: the case of Regina Viarum
No full textIntegrating low-cost RTK positioning services with a web based track log management system
No full textLocation-based collaborative platforms are proving
to be an effective and widely adopted solution for geo-spatial
data collection, update, and sharing. Popular collaborative
projects like OpenStreetMap, Wikimapia, and other services
that collect and publish user-generated geographic contents
have been fostered by the increasing availability of locationaware
devices. These instruments include global positioning
system (GPS)-enabled phones and low-cost GPS receivers,
which are employed for quick field surveys at both professional
and nonprofessional levels. Nevertheless, the data collected
with such devices are often inaccurate. To alleviate this
drawback, an integration of modern web technologies and
online services with an advanced positioning technique is
implemented. A web-based prototype for quality-based data
selection of GPS tracks, managing track logs and point of
interests is integrated with the goGPS software. This combined
system applies the principle of real-time kinematic
(RTK) positioning to low-cost single-frequency receivers.
The workflow consists of acquiring the raw GPS measurements
from the user’s receiver and from a network of GPS
stations, processing data by RTK positioning through the goGPS Kalman filter algorithm, sending the accurate positioning
data to the web-based system, performing further
quality enhancements, and logging and displaying the data.
Tests were performed in open areas and various dense urban
environments, comparing the results obtained by standard
GPS devices and by goGPS RTK positioning. Results were
promising and suggest that the integration of web technologies
with advanced geodetic techniques applied to low-cost
instruments can be an effective solution to collect, update, and
share accurate location data on collaborative platforms
Enhanced satellite positioning as a web service with goGPS open source software
No full textProviding enhanced satellite positioning as a web service can be an effective way to enable low-level GPS receivers to perform surveys with a good accuracy and to reduce hardware cost, by removing computation capability and embedded proprietary software. goGPS is an open source application for achieving sub-meter accuracy with low-cost GPS receivers by exploiting real-time kinematic positioning, Kalman filtering, aid from a digital terrain model, and in general by integrating GPS data with other sources of information. Since goGPS directly processes raw GPS observations, it provides a means to substitute black-box processing components (e.g., GPS chipsets) with open source positioning software. goGPS can work either in real-time or post-processing, by acquiring raw GPS data in input and providing positioning (i.e., coordinates) in output. Though originally developed in MATLAB, goGPS was recently ported to Java in order to have the possibility to provide it as a web service, thus allowing a wider user base to develop and use it. Since real-time GPS positioning heavily relies on fast matrix computation, a careful selection of Java matrix libraries was carried out in order to obtain optimal performances. An Open Geospatial Consortium standard Web Processing Service (WPS) implementation of goGPS by means of ZOO WPS framework was developed and tested in order to let lightweight clients just acquire raw GPS data, send them to a server for processing, and receive back the accurate positioning
GeoGuard: un nuovo servizio di monitoraggio geodetico per l’osservazione di segnali geodinamici
No full text- …
