Towards the new Croatian terrestrial reference frame based on CROPOS--preliminary results/U susret novom Hrvatskom terestrickom referentnom okviru temeljenom na CROPOS-u--preliminary rezultati

Since the establishment of CROPOS, almost seven years have passed. Initial and also the last adjustment CROPOS network was carried out in 2008 using only seven 24h session data in GPS Week 1503 (ETRF2000 R05; e2008,83). In the recent period there have been significant changes--Croatian State Geodetic Administration (CSGA) signed an agreement on the exchange of data of national positioning systems neighboring countries: Slovenia (SIGNAL), Hungary (GNSSnet.hu), Montenegro (MontePOS), Federation of Bosnia and Herzegovina (FBiHPOS) and Republika Srpska (SRPOS). This paper presents the results of long-term stability of coordinates of CROPOS stations through absolute comparison of ETRF2000 coordinates from initial adjustment with the combined networked solution of CROPOS and nearby positioning systems, calculated on the basis of 1463 daily solutions for the time span of four years.