The ETRS89 is maintained thanks to the creation of a European permanent GPS station network,
known as the EUREF permanent network (EPN).
This permanent network consists of part of the GNSS permanent tracking stations distributed over almost all
European countries. The EPN consists of the following components:
Tracking Stations (TS): They set up and operate the permanent GNSS tracking
receivers and antennae on suitable geodetic markers.
Operational Centres (OC): They perform data validation, conversion of raw
data to Receiver Independent Exchange Format (RINEX), data compression, and data upload to
a data centre through the Internet. For some stations the OC is identical with the institution
responsible for the respective station (i.e., the OC is identical with the TS).
Local Data Centres (LDC): They receive the data of all stations of a local
network and distribute them to the users (local and EPN). One or more of these stations
are part of the EPN network. For many of the local networks the LDC will be identical with
their Operational Centre.
Local Analysis Centres (LAC): They process a subnetwork of EPN stations
and deliver weekly free network solutions to the Combination Centre. All processing is done
following specific international guidelines. The subnetworks have been designed in such a
way that each station has minimally three analysis centres. Thanks to this redundancy errors
can be eliminated without any problems. This solution is available in the SINEX format
(Software Independent Exchange format).
A Combination Centre (CC): It combines the individual subnetwork solutions
into one official EPN solution including all tracking stations. This solution is send to
the IGS where it is integrated in the global GNSS network. Once a year a multi-year EUREF
solution is sent to the IERS, with as direct result that the EUREF stations become primary
A Central Bureau, which coordinates the activities of the tracking stations,
data centres and analysis centres. It distributes standards and guidelines. It maintains the
history information of all tracking stations, checks the individual coordinate time series
and notifies the EUREF user community when a station does not fulfil the standards or when
irregular behaviour is detected through a coordinate variation.