5.1.3 National GPS Network (OGPSH)
The reference system was classified for decades in Hungary, even the information on the projection system was not available for users outside of Hungary. To meet the requirements of the domestic and international professional commun-ity, these pieces of information were released for public use in the last four years. Recently, based on earlier results achieved in IAG and CERCO WG VIII, a Description Directory of Hungarian Reference and Projection Systems (4th revised Edition) June 1995 has been issued by FÖMI. The paper gives an overview on the EOV (Unified National Projection) parameters, the HD72, the Hungarian vertical system and the relation of HD-72 to the WGS-72 and EUREF-89 (WGS-84) systems.
- 5 sites of EUREF Networks (as Hungarian part of EUREF completed in 1991)
- 19 sites of zero-order GPS Network (completed in 1991)
- 24 sites of the OGPSH have been completely measured, both in HD72 and three dimensional,
- 1138 sites of the OGPSH (east to the river Danube (total 50% was completed in 1995-96)
- The 3D spatial coordinates of the GPS sites are referred to the EUREF-89 reference frame.
This Directory enables the user (e.g. the MEGRIN Data Service Centre) to perform per point coordinate transformation between the systems mentioned (EOV to EUREF-89 and WGS and vice versa). This capability provides a wide range of interdisciplinary utilisation in geo-referencing, spatial data handling and GIS applications even in regional and continental level. (To obtain a copy of the document in Hungarian or English please write Dr. Sz. MIHÁLY, Scientific Vice Director, FÖMI, Bosnyák tér 5, 1149 Budapest, Hungary). The Description Directory is aimed to be introduced as Hungarian Standard. A centralized Geodetic Point Database of horizontal, vertical and 3D networks of Hungary has been elaborated and introduced by FÖMI. Loading the data into the database has already been started and is expected to be finished in 1997.
Some of the recent and anticipated follow-on activities are:
Upon the call of IAG/EUREF subcommission of 1994 Hungary has prepared data expressed in geopotential index numbers for the purpose of connecting the Hungarian vertical network to the UELN frame. The Hungarian IAG/EUREF contact person, Dr. József Ádám handed over the data to Prof. Augath on the Subcommission's Technical Working Group meeting on 15-16 December, 1994 in Germany.
- Finishing the vertical network using GPS technology and levelling,
- Some major actions to connect the Hungarian geodetic fundamentals to EUREF and UELN,
- Densification of the National Zero-Order GPS Network in order to obtain the 1138-site National GPS Network,
- National GPS Observation Service for use in different applications,
- Maintaining and analysing the Hungarian GPS Deformation Network,
- Participating the International GPS Geodynamic Service,
- Adapting GPS technologies for application in different survey tasks.
- Using the Hungarian 10 year-old Gödöllő standard baseline for national and international calibrations
- Participating in the European Vertical GPS Reference Network (EUVN) observation campaign
- Improving of the present geoid solution for GPS-heighting applications
Talks have been held with Croatian and Slovenian colleagues on works of connecting the neighbouring national vertical frames.
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