What is M3G
M3G stands for “Metadata Management and distribution system for Multiple GNSS Networks”. M3G allows to upload, validate, and distribute GNSS station metadata such as IGS-style site logs, information about local networks, DOIs, nominal data provision, data licenses attached to the daily RINEX data, etc... It has been primarily developed to support the EPOS, EPN, and EPN densification GNSS networks. M3G is developed and maintained by the Royal Observatory of Belgium (ROB).
Using M3G

To edit metadata, it is necessary to login in to M3G. All agencies maintaining EPN or EPN densification stations metadata (the so-called Operational Centres) have received their login by email. Agencies maintaining metadata of EPOS stations will be sent a login as soon as we receive the completed and signed EPOS-GNSS supplier letter from the station owner. Visit the Guidelines section for the responsibilities of Data Supplier and Operational Centre.

Site log updates
Site log updates of EPN (or EPN densification) stations will automatically flow to the EPN Central Bureau. Site log updates of EPOS stations will automatically flow to the EPOS GNSS Data Gateway (DGW).

Networks and projects

Stations whose metadata are integrated in M3G can belong to GNSS networks and/or GNSS projects.

A GNSS network regroups continuously operating GNSS stations

  • whose station managers committed to manage the stations according to a well-defined set of guidelines e.g., use of common standards for site monumentation, receiver and antenna equipment, data exchange format, etc.
  • whose observation data flow and data availability are regulated by rules established within the GNSS network.
A network manager (or coordinator) has the authority to include new stations in the GNSS network as soon as the GNSS stations comply with network-specific rules.

A GNSS project regroups GNSS stations

  • whose GNSS observation data are used in the products generated within the context of a scientific project or, in other words, whose observation data were collected by the GNSS analysis centers contributing to the project.
Contrary to GNSS networks, the GNSS station managers have not committed to contribute to a project and, consequently, cannot propose to include their GNSS stations in an M3G project. Examples of M3G projects are the E-GVAP project (generating tropospheric products) or the EPN Densification project (generating station positions and velocities).