Uniform National Horizontal Network (EOVA)

The EOVA is based on the Hungarian Datum 1972, the network orientation is provided by 40 Laplace-points and the scale is maintained by 23 EDM lines.

Parameters connecting the Hungarian control network to the EUREF-89 and ED-87 systems have already been measured, computed and finalised.

For high order scaling, a 864-m long Standard Baseline at Gödöllő town (about 30 km from Budapest) has been measured with Väisälä interferometric method and Kern Mekometer in co-operation with Finnish Geodetic Institute in 1987 and re-measured in 1999. This very stable baseline with 5 pillars is accredited for EDM calibrations for national and international use.

Fig. 2.
Sites of the 1st order Uniform National Horizontal Network

The network (Fig. 2.) consists of:

• 163 sites of 1st order (146 points within Hungary and 17 points in the neighbouring countries),
• 1974 sites of 3rd order,
• 4307 sites of principal 4th order,
• 43780 sites of 4th order exist in EOVA.

The 1st, 3rd and principal 4th order sites have 10306 orientation sites. 6080 orientation sites have co-ordinates.

An EOVA Database was created and is operated by FÖMI, containing the positional and descriptive data of horizontal control sites (1^st, 3^rd and 4^st order) as well as their sketching. It contains: the number of the sites, the vertical and horizontal co-ordinates of the sites in the EOV and old projection systems, the location of the sites (county, settlement, sheet number), the date of determination and checking actions, sketch of approach ( Fig. 3.).

Fig. 3.
Example printout from EOVA Database