Projects / Programmes
Development of methodology and system for verification of GNSS permanent networks and stations
| Code |
Science |
Field |
Subfield |
| 2.17.00 |
Engineering sciences and technologies |
Geodesy |
|
| Code |
Science |
Field |
| P515 |
Natural sciences and mathematics |
Geodesy |
| Code |
Science |
Field |
| 2.07 |
Engineering and Technology |
Environmental engineering
|
GNSS, continuously operating GNSS station, network of continuously operating GNSS stations, coordinate system, reliability
Researchers (11)
Organisations (2)
Abstract
According to the Property Registration Act of 2008, all procedures in Slovenia related to the registration of real estate must be managed in the new national coordinate system ETRF89/TM and D96/TM, respectively. National coordinate system is realized with a network continuously operating reference stations (CORS) GNSS stations SIGNAL (Slovenia-Geodesy-NAvigation-Location) and a network of numerous passive geodetic points GNSS EUREF on the territory of Slovenia. The SIGNAL network has been operating since 2001 and consists of 16 permanently operating stations located allover Slovenia. SIGNAL network additionally contains also stations from all four neighboring countries for enhancing the quality of services in the border regions of Slovenia. In 2016 a combined geodetic net of 0. order was established, but it is currently not directly used for the realization of the reference system of Slovenia.
Realization of national coordinate system is done with SIGNAL network and since it is also used-defined network, it represents the simplest and fasters connection to the national coordinate system. Users may determine coordinates of new geodetic points on a basis of SIGNAL in national coordinate system in real-time as well as in post-processing mode. Real-time positioning is possible continuously (365/25/7) on a basis of transmitted observations from single CORS (RTK method) as well as on a basis of network services (VRS - Virtual Reference Station and MAC – Master-Auxiliary Concept). In case of post-processing mode, users may get RINEX files of any CORS as well as for manually determined VRS point from web portal of SIGNAL network. Using post-processing mode for positioning generally results with higher quality compared to real-time mode, and on the other hand, it allows SIGNAL network to ensure its products even in case when real-time mode is not possible in field survey when the connection to the network is not possible.
Geospatial data determined on a basis of SIGNAL network are determined in national coordinate system with high quality, regardless of location and time. However, this is possible only with appropriate control over the operation of the network and individual stations, with appropriate data distribution, as well as with appropriate determination of stations’ coordinates, that are monitored in near real-time. Geospatial data of appropriate quality, particularly geospatial data related to national spatial data infrastructure, represented in unique coordinate system are the basis for qualitative spatial state policy.
However, CORS of SIGNAL and combined geodetic network or 0. order are not the only CORS on the territory of Slovenia. For the purposes of real estate registering and other geospatial projects, private sector also uses CORS, network of CORS or geodetic points, forming the passive geodetic network, that are not part of state determined GNSS networks. These are stations, networks and geodetic points, established by private companies that are used for positioning with adequate relative precision, but with questionable precision and accuracy within the national coordinate system. Currently, private stations and networks are being established on a basis of private sector needs and without any pre-determined procedure and criteria in order to ensure high quality agreement with national coordinate system. The quality level of private CORSs determined coordinates and their agreement with national coordinate system may currently only be speculated. Due to the lack of knowledge of the situation, we may also only speculate about the quality and reliability of private CORSs establishment and maintenance. This only means that the Surveying and Mapping Authority of the RS has no control over the quality of stations or networks as well as over the positioning in the national coordinate system.
Geospatial data are useful only when presented in unique coordinate system of high quality, so it is only reasonable that all C
Significance for science
Definition, realization and maintenance of the national coordinate systems is guided by the Sub Commission EUREF - 1.3 Regional Reference Frames of the IAG (International Association of Geodesy) Commission 1 Reference Frames. Its objectives are theoretical and applied research activities to assure qualitative positioning in 3D space. One of the EUREF competences is reviewed use of privately owned GNSS continuously operated reference stations (CORS) and network CORS, together with the supervision of its daily activities. Aim of such a scientific support at the global level is establishment of the conditions, infrastructure and activities for the spatially oriented data acquisition with respect to conditions and occurrence. The majority of human activities take place in the physical space, so in order to be able to master the space around us, quality spatial data are essential.
Nowadays, GNSS continuously operated reference stations (CORS) networks, either public or private, are the key infrastructure for the spatially oriented data acquisition. With its support, users can obtain quality coordinates in the national or global coordinate system rather easily. In Slovenia, there are two public GNSS CORS networks, network SIGNAL and Zero order combined geodetic network. Both represent realization of the Slovenian horizontal coordinate system. They enable continuous observations of the national coordinate system condition as well numerous factors causing effects on its condition. Besides these two networks there are more than ten privately owned GNSS continuously operated reference stations and at least one CORS network. Practical usage of GNSS technology demands linkage and merge of these stations and network into one united CORS network, organized in the hierarchical sense. This new network should enable positioning at the whole territory of the state at suitable quality level.
One of the main roles of Geodesy is the determination of the Earth's surface geometry and its temporal variations. In such respect, one treats the Earth as a deformable body, burdened with global, regional and local geodynamic processes. Slovenia is located at the geologically, tectonically and seismically very interesting part of the Eurasian tectonic plate. It lies at the convergent boundary of the Adratic microplate, Dinarides and Panonnian basin. Geodynamics of its territory is extremely complex, so modelling the activities in this region presents one of the most challenging tasks in the field of Geology and Tectonics.
Among numerous factors influencing the condition of the national coordinate system, Geodynamics is the most important. Data from privately owned GNSS reference stations and networks could improve our knowledge about the geodynamic processes at the territory of Slovenia, making the research area wider thus extending the number of investigating stations. There is of course necessity these private stations to be realized in accordance with scientifically approved requirements. Temporal changes of coordinates are the basis for determination of geokinematic processes. Time series analysis is the basis segment in estimation of geodynamic and tectonic activities as well in decision making of introducing time-dependent national coordinate system. Analysis of data from the private stations could be used in solving specific geodetic problems as well wider problems regarding the geokinematic and geodynamic processes in order to set up suitable tectonic models, which are the key input for improving the seismic hazard assessment of the country.
One of the products of the analysis of CORS measurements is also the estimation of the tropospheric refraction, enabling studies of spatial and temporal distribution of water vapour in the troposphere. This could be valuable information for meteorological models for the weather forecasts. CORSs enable monitoring of the ionosphere, which is related to the various processes on the Sun. In both cases, the rel
Significance for the country
At the turn of the millennium, establishment of regional and national networks of continuously operating reference GNSS stations (CORSs) presented a new milestone for measuring and modelling the space. GNSS networks served for rapid and reliable geo-referencing by providing homogeneous accuracy, regardless of a location of measurements. The use of CORSs optimized the organization of the fieldwork and the performance of geodetic services accelerated drastically. Consequently, the entire process resulted in positive economic and financial effects. However, the nature of the GNSS data acquisition (prior only by GPS) with the foundation in relative positioning also required a large financial contribution from the users. At first, users had to dispose of at least two instruments to perform quality positioning. Therefore, to save on cost of purchasing of two instruments, the idea of setting up a CORS was successfully implemented. Several CORSs were later connected to the networks, which were originally established under the national auspices. In Slovenia, the national CORS network SIGNAL started to be established in 2000, while its full-operational epoch refers to 2006. In 2016, the CORS infrastructure enlarged by the combined geodetic network, also called the zero-order network, which is superior to the SIGNAL, but not directly accessible to the users. Since it was established to monitor the quality of the SIGNAL network, its primary purpose is to provide reliable data to acquire quality positioning in the national reference coordinate system by the use of SIGNAL that could be further used in different economics sectors.
While the SIGNAL as well as the zero-order network are owned by the state, other CORSs remain in the private ownership. In the past, they were established mainly for the geodetic purposes. Some private individuals or companies have established their CORSs already prior of the SIGNAL era or at the time when the national CORS network was in its construction phase, but yet not fully operating. Private CORSs were mostly established due to the excessive distance from the national stations, since in order to achieve a high quality of positioning, the rule applies that the measurement can be carried out at a distance of up to 15 km from the reference station. However, in the recent past, when the SIGNAL network was already operating, the reasons for setting up private CORSs have changed. Mostly they were due to the non-optimal coverage with the mobile phone signal, through which the real-time data flow is transmitted in the SIGNAL. In some areas, the real-time measurements could not be performed due to a lack or complete failure of mobile-signal reception. Therefore, the private CORS ensured real-time data transmission differently, i.e. by the use of radio link.
The insight into the transparent process of the private CORSs establishment as well as the management of their data (including the possibility of real-time data flow) in national records will affect both, the owners/managers of private CORSs or networks as well as their users. In the problematic areas, where the problem of mobile signal reception remains, the users will be able to use private CORS services through the data transmission by the radio link. In the current project, acquired knowledge could be transferred or exchanged between various economic subjects. Therefore, it is important to present a methodology, which will enable the users of private CORSs/networks to perform high quality geodetic measurements to acquire data in accordance with the national reference coordinate basis, or in such a way that the data will not affect the local geometry of the national reference coordinate system. For this, the supervision of the establishment and operation of private CORSs/networks and the national records of their metadata establishment is of key importance for the quality performance their services to be used in different strategic solutions.
Enhancing
Most important scientific results
Most important socioeconomically and culturally relevant results
Annual report
2019,
2020
