Adjustment and transformation strategies of ItalPoS permanent GNSS network

A private network of 133 Global Navigation Satellite Systems (GNSS) permanent sites, named ItalPoS (Italian Positioning Service) and uniformly covering the entire Italian territory, was established in April 2006 by the Italian Division of Leica Geosystems S.p.A. This network also involves several GPS stations of the INGV (Italian National Institute of Geophysics and Volcanology) RING (Real-time Integrated National Gps) network and GPS stations from other public and private bodies. Indeed Leica Geosystems contributed with its experience and its products to these networks which currently fulfil the national coverage where there are no ItalPoS stations. For instance, the purpose of the ItalPoS network is mainly GNSS data distribution in terms of real time corrections and RINEX files for the post-processing. In order to compute and distribute to private and scientific users a set of adjusted coordinates of the ItalPoS network in the IGS05 and ETRF89-2000 reference frames, a dataset of RINEX of about 120 GPS permanent sites was created and processed, using the distributed sessions approach, by means of Gamit/Globk 10.3 GPS data processor, also using some SOPAC (Scripps Orbits and Permanent Array Center) and EUREF (European Permanent Network) solutions to improve the reference frame definition and the internal constraints. This paper describes all the strategies adopted to estimate coordinates and velocities of the ItalPoS Network in IGS05 and in ETRF89-2000 reference frames in the whole Italian territory.