Quality spatial data registries are an important part of every national spatial data infrastructure. The most important part of the national spatial data infrastructure is national geodetic reference system since all national spatial data registries must be referenced to it. Furthermore, it is also used for majority of surveying and other geodetic tasks. Slovenian national geodetic reference system consists of separate horizontal and vertical component.
Horizontal component of Slovenian national coordinate system is realised by sixteen permanent GNSS (Global Navigation Satellite System) stations of Slovenian national GNSS permanent network named SIGNAL (Slovenia-Geodesy-NAvigation-Location). Furthermore, the SIGNAL network is also a public network. It provides access to the national horizontal coordinate system to different public users, which use it for obtaining accurate positions of objects and phenomena on the Earth’s surface. The SIGNAL network has been operating since 2000. SIGNAL’s data are used by users for RTK (Real-Time Kinematic) positioning as well as for post-processing positioning. RTK positioning can be done as Single Base RTK (user receives data from only one permanent station) or as network RTK (user receives one of the supported network product). The SIGNAL network supports two network products – VRS (Virtual Reference Station) and MAC (Master-Auxiliary Concept). For the purpose of post-processing users can order RINEX files, which are stored in RINEX archive. Post-processing positioning has higher accuracy compared to RTK and makes possible to obtain accurate coordinate even in case when SIGNAL’s real-time products are not accessible due to some failure.
Recently, the modernisation of Slovenian national spatial data infrastructure has been carried out. One of the most important things that has been done within this project is establishment of the zero order CGN (Combined Geodetic Network). The main goal of the zero order CGN is realisation of Slovenian national horizontal and vertical coordinate system. A part of it is also GNSS permanent network that consists of six permanent GNSS stations and is used for continuous monitoring of possible deformation of the national coordinate system. The SIGNAL network remains a public network while the zero order CGN is not meant to be a public network. The zero order CGN is also used as a part of SIGNAL’s quality control.
Given the importance of both networks (the SIGNAL network and the zero order CGN) it is necessary that they operate continuously without major interruptions and provide GNSS observations, products and services of the highest quality. In reality, both networks are sometimes facing several different problems, which are causing interruptions of their operation and affecting the quality of their products and services.
Reasons for interruptions in operation of considered networks are different, some are predictable (hardware/software upgrades), others are not (hardware/software failures and other problems). In addition to mentioned problems the SIGNAL network is faced also with problems of individual users and (user) problems that are not directly related to the SIGNAL network but still affect the quality of acquired position.
The starting point of the project are the following problems of the SIGNAL network and the zero order CGN:
- problems that are causing interruptions in operation of the SIGNAL network and/or affecting the quality of its products and services (e.g. hardware/software problems),
- problems of the individual users of the SIGNAL network (e.g. network connection problems, lost passwords, wrong rover settings)
- problems that are not directly related to the SIGNAL network (e.g. incorrect execution of RTK/post-processing positioning, faulty GNSS instrument) but users usually first consider that they have problems with the SIGNAL network and therefore unnecessarily contact the technical support
- problems that are causing interruptions in operation of the zero order CGN and/or affecting the quality of its products (e.g. hardware/software problems).
A detailed review of the SIGNAL network and the zero order CGN operation will be done. Therefore, two analyses will be carried out first:
- analysis of technical problems of the SIGNAL network and the zero order CGN,
- analysis of SIGNAL’s user problems and user experiences.
Then, based on our own research and with help of good practices from comparable foreign networks, a methodology for upgrading the quality control of the SIGNAL network and the zero order CGN, solving technical problems in the operation of those two networks and solving user problems of the SIGNAL network. Developed methodology will consist of several suggestions for new quality control procedures, troubleshooting procedures, updated manuals for network administrators and some additional user guidance along with training courses proposal for proper use of the SIGNAL network and proper execution of GNSS surveying. To assess the adequacy of the proposed methodology excessive testing will be performed. Based on acquired results necessary modifications of the developed methodology will be done. As the final result of the project a proposal for implementation of developed methodology into the operation of the SIGNAL network and the zero order CGN will be made. Throughout the course of the project, the end users of the project will be informed about all ongoing activities and results on regular basis. The results of the project will also be published in various scientific and professional journals and presented on different conferences.
The final goal of the project is therefore to give The Surveying and Mapping Authority of Republic Slovenia new proposal for the implementation of the methodology into the operation of the SIGNAL network and the zero order CGN. This will ensure systematic control, thus improving the reliability and quality of the operation of those two networks and the quality of their products. Those networks would consequently provide a positioning of higher quality in the national coordinate system.
The project will be implemented by partners the Geodetic Institute of Slovenia (GI) and the Faculty of Civil and Geodetic Engineering of the University of Ljubljana (UL FGG) who regularly collaborate in different research and development projects related to the establishment and realization of the national coordinate system in Slovenia, the establishment and development of the SIGNAL network and the zero order CGN, the development of methodology and software solutions for the transformation of coordinate systems in geodesy, the determination of the land and sea geoid model, and a number of conceptual, development and practical tasks related to the use of GNSS technology in different practically fields of geodesy.
Through the introduction of more extensive quality control of the operational processes of the SIGNAL network and the zero order CGN, which we will propose in this project, we will in the long run provide a more stable state coordinate system, which is also important for the economy. In this way, all measurements of objects in the space, carried out by either surveyors or other profiles, will be measured more accurately.