The reliability of the EPN is based on the redundancy of its components:
GNSS Tracking Network
The EPN tracking network consists of geodetic GNSS (Global Navigation Satellite Systems) receivers and antennae which are permanently observing GNSS signals and installed at stable geodetic markers. These permanently observing stations are operated on a best effort basis by National Mapping Agencies, Universities, Research Agencies, etc… all over Europe. Through a commitment letter they agree to operate their EPN stations following specific scientific guidelines and make the GNSS data freely available to EUREF and its users. These guidelines specify e.g. the GNSS signals to be observed, the maintenance of station meta-data, the procedure for uploading the data to EUREF (format, frequency, latency), etc...
Since the start of the EPN in 1996, the number of GNSS tracking stations delivering data to the EPN is steadily growing (plot) and several stations are presently in the process of being included in the EPN. Agencies wishing to include new stations in the EPN tracking network are invited to check "Procedure for Becoming an EPN Station".
The current status of the EPN tracking network is available from here : list, map.
In addition to the EPN stations, several hundreds of other permanent GNSS tracking stations exist in Europe. The observations of a large majority of these stations are analyzed by EPN analysis centres in order to densify the EPN. The data of these EPN densification stations are available under specific conditions defined by their operation agency.
The Operational Centres are the agencies (list) responsible for uploading GNSS data from one of more EPN tracking stations to the EPN data centres (for file-based data) and broadcasters (for real-time data). This data upload is done following agreed upon guidelines. The Operational Centres are also responsible for maintaining the meta-data of the EPN stations under their responsibility.
EPN Data Centres provide access to EPN station data and EPN products (only selected data centres).
Access to EPN station data is distributed, using an open data policy, through several Data Centres which receive the GNSS data from the Operational Centres and distribute them free of charge to the users:
- Daily and hourly EPN 30-sec. data in the RINEX format: Local Data Centres (mostly national, list) and Regional Data Centres (full EPN, list); data downloadable through anonymous ftp
- Daily historical EPN 30-sec. data in the RINEX format: Historical Repository (full EPN, list); data downloadable through anonymous ftp
- Real-time EPN data in the RTCM format: Local Broadcasters (mostly national, list) and Regional Broadcasters (full EPN, list); data streams available using Ntrip-Client software
- 15-min. near real-time 1 Hz. EPN data in the RINEX format: High Rate Data Centre (list) ; data downloadable through anonymous ftp
EPN Analysis Centres (list) analyse the data from EPN stations, following agreed upon standards, to contribute to the EPN products generated by several EPN Product Coordinators. They perform at least one of the following tasks:
- Estimate routinely daily and weekly station positions and station zenith tropospheric path delays for a part of the EPN stations. These solutions are used as input for the generation of the daily/weekly combined EPN positions and combined EPN troposphere solution comprising the full EPN tracking network.
- Analyse date from GNSS stations (including a defined set of EPN stations) to contribute to products generated by EUREF working groups (e.g. reprocessing, densification, monitoring,...) or EPN products which are still under development.
- EPN station positions and velocities:
- Daily position estimates, based on one day of GNSS data, updated daily ; used for station monitoring. Learn more
- Weekly position estimates, based on one week of data, updated weekly – occasional reprocessing is performed in order to align historical weekly solutions with present state-of-the-art results ; used as instantaneous realization of the ETRS89. Learn more
- Long-term position and velocities, based on all available EPN data, updated each 15 weeks ; used as EUREF’s official realization of the ETRS89. Learn more
- EPN zenith tropospheric path delay estimates. Learn more
- ETRS89 satellite orbit and clock correction streams. Learn more
These products support:
- Improving and providing access to the European Terrestrial Reference Frame (ETRS89)
- Monitoring the Earth troposphere
The day-to-day management of the EPN is done by the EPN Central Bureau managed by the EPN Network Coordinator. The EPN network coordinator forms together with several other Coordinators and Working Group Chairs the EPN Coordination Group.