The GNSS observation data from the EPN are analysed by two different types of Analysis Centres:
EPN Analysis Centres (Only Post-processing)
In order to optimize the operational EPN data processing, the principle of distributed processing is used. In this approach the EPN is divided in well-defined subnetworks which are separately processed by different EPN Analysis Centres (ACs) following the rules and guidelines set up by the International GNSS Service and supplemented by the EUREF Governing Board. The AC estimate daily and weekly station positions and station zenith tropospheric path delays for a part of the EPN stations.
We distinguish between:
- Rapid products: available with a latency of 1 day and computed using rapid orbits/clocks provided by the IGS or one of its Analysis Centres.
- Final products: available with a latency of 2-3 weeks and computed using final orbits/clocks provided by the IGS or one of its Analysis Centres.
The ACs provide mandatory the following products:
- Final free-network position estimates (SINEX format): daily and weekly (availability).
- Final daily Zenith Path Delay estimates.
In addition, the AC are encouraged to submit in addition:
- Rapid daily position estimates.
- Final daily tropospheric gradients.
The solutions provided by the EPN Analysis Centres are combined:
- by the Analysis Combination Centre (ACC) to generate daily/weekly combined EPN position solutions tied to the latest ITRS realization
- by the EPN Troposphere Coordinator to generate the combined EPN troposphere solution
The weekly combined EPN position solutions are used by the Reference Frame Coordinator to issue 15-weekly updates of the multi-year EPN position/velocity solution and residual position time series.
Dedicated Analysis Centres
Dedicated Analysis Centres (DAC) analyse data from GNSS stations (including a defined set of EPN stations) to contribute to EPN products which are still under development, or products generated by EUREF working groups, e.g. reprocessing (EPN-repro1, EPN-repro2), densification, real-time analysis, ...