ESTPOS is the Estonian Permanent GNSS (Global Navigation Satellite System) Reference Station Network. The first CORS (Continously Operating Reference Station) in Suurupi (SUR4) was established already in 1996. In 2007-2008, a network of 9 GNSS permanent stations was established. In 2014-2016, the network was densified with 19 new CORS and upgraded with modern equipment and software. As of 2019, the ESTPOS network consists of 29 GNSS permanent stations which are distributed homogenously throughout the territory of Estonia. In addition to the 29 permanent stations operated by the Land Board, data from the Finnish and Latvian GNSS permanent stations as well as from the stations operated by the Estonian Maritime Administration are used. Therefore, the border areas of Estonia have a much better coverage. Four ESTPOS stations are included in the EUREF Permanent GNSS Network (EPN).
All rerefence stations are equipped with Leica Ring Choke antennas (AR25) and GNSS receivers (GR25) that can access signals from a variety of constellations: GPS, GLONASS, Galileo and Beidou. However, due to software limitations only GPS, GLONASS and Galileo can be utilized in post-processing and network RTK solutions.
The ESTPOS network is necessary for monitoring the components of the Estonian reference system, first and foremost for tracking changes in horizontal and vertical deformations, as Estonia is located on the periphery of the Scandinavian post-glacial rebound area. A modern GNSS permanent station network also ensures the availability of precise spatial data in the country and allows real time point positioning with an accuracy of 2-3 cm.
ESTPOS is widely used by the Land Board and other governmental institutions in Estonia, and for educational and research purposes. ESTPOS is currently not availble for commercial use.