M3G stands for “Metadata Management and distribution system for Multiple GNSS Networks”. It is a software developed by the Royal Observatory of Belgium (ROB). ROB runs M3G on https://gnss-metadata.eu/ where registered agencies can upload, validate, and distribute GNSS station metadata. The GNSS station metadata comprise IGS-style site log files, but also information about local networks, DOI, nominal data submissions, etc...
M3G has been developed primarily to serve the EPOS, EPN, and EPN densification GNSS networks.
Collected Metadata
  • The information in the so-called IGS site log
  • The local/national/virtual/international networks in which the station is integrated
  • The nominal types of RINEX data that the station is submitting (RINEX version and upload frequency)
  • The license on the data (only for EPOS stations)
  • The embargo time on the data (only for EPOS stations)
If the submitted metadata is part of the metadata in the site log, then
  • the updated site log of EPN or EPN densification stations will automatically flow to the EPN Central Bureau. It will take up to 15 minutes for the updated site log to show up at the EPN Central Bureau.
  • the updated site log of EPOS stations will automatically flow to the EPOS GNSS Data Gateway.
For IGS stations, M3G will send a notification to the IGS Central Bureau informing them that the site log was updated. However, the Operational Centre (or station manager) will still have to submit the site log to the IGS.
Not yet, but it is on our to-do list. An example is to provide web services to update firmware versions. Suggestions are welcome.
M3G collects the license on the data and its embargo time only for the stations included in the EPOS network. EUREF is presently not requesting this information for the EPN and EPN densification stations. Consequently, the registered agency will be requested to provide this information only for the EPOS stations that it manages.
All agencies responsible for maintaining GNSS station metadata of EPN, EPOS, or EPN densification stations have a login account for M3G. M3G calls them the “Registered Agencies”. Each registered agency has one unique login/password.
The registered agency that maintains the metadata does not necessarily have to be the station owner. If both are different agencies, then it is expected that the station owner has formally agreed that the registered agency maintains its station metadata in M3G. For EPN or EPN densification stations, we do not need to see this agreement. However, for EPOS stations, we need that the data owner indicates who is maintaining the station metadata in M3G. This information is provided by the data owner through the EPOS-GNSS data supplier letter.
Logging in to M3G is only required when you want to update metadata of your stations, agency, associated agencies, networks, ....
Your LOGIN ID is the unique identification code of your agency. You can find it from Registered Agencies under the column "Unique agency ID". If your agency is not in the list, then contact the M3G team.
Once you inserted your LOGIN ID, you need to provide your password. If you do not remember your password, then use the button “Reset Password” and all the contacts listed in User agency will get an email allowing to reset the password. You now have all information to log in to M3G.
After pushing the "Reset Password" button, all the contacts set up in the User agency will get an receive an email to reset the password of your agency. If you are not receiving this email, then this can be due to your spam filter or because you are not listed in M3G as one of the agency contacts (and consequently do not have permission to reset the password). In this case, you need to contact one of your colleagues who is included in the contact list, ask him/her to reset the password, log in to M3G, and add you to the list of agency contacts.
You will get access to the agency-specific menu with the following sub-items:
  • "Stations” allows to edit all information related to the stations, e.g. site log, nominal data provision, networks to which the station belows, data licenses, etc….
  • “User Agency” is used to set up your own agency and its contact persons. New contact persons can be added by clicking on the +.
  • “Associated Agencies” is used to set up all agencies (and their contact persons) which are involved in the operation of your stations. They can be the on-site agencies, the agencies managing the local networks to which the station contributes, etc…. New associated agencies can be added by clicking on the +.
  • “Managed Networks” shows all the networks that you have created in M3G. Additional networks can be added by clicking on the +.
Note that ALL agencies and contact persons used later on in the site log, must be defined in the "User Agency" of "Associated Agencies" submenus.
My station list
  • Login to M3G
  • Go to the agency-specific section and click on "Stations" -> "Add new station(s)"
  • Follow the on-line help (by clicking on ? in the title of the page)
First, update the site log by entering the removal date of the equipment in "Date Removed" in the last receiver and antenna sections. Save and submit the site log. Then send an email to the M3G team to inform us that the station has been decommissioned. We will then swith the status of your station from ACTIVE to FORMER.
Note that decommissioned stations must not be removed from the station list of the User Agency (or Operational Center) because the metadata of these stations are still valuable for reprocessing of historical data.
  • Send an email to the M3G team listing the stations that will be handed over to another agency. Put the agency that will take over in copy.
  • The M3G administrator will check if the other agency has a login in M3G, if not, a login will first be created.
  • The M3G administrator will remove the stations from your User agency.
  • The M3G team will invite the other agency to add the stations to be transfered to its own User agency station list.
For EPOS stations, the data owner needs in addition to send us an updated EPOS-GNSS data supplier letter to indicate the new agency taking care of the metadata management in M3G.
  • the station name (9-char ID, e.g. BRUX00BEL)
  • the network to which you want to propose the station (EPN, EPN densification, or EPOS network)
  • the RINEX data types that you will provide. At the moment, it is mandatory to provide at least RINEX 2 data
  • for EPOS stations only: indicate the type of license and the embargo time on the data
The only reason for removing a station from your agency in M3G is: your agency is not responsible anymore for maintaining the metadata of the station and the station might need to be attributed to another agency. For security reasons, starting with M3G v1.0, users cannot remove stations anymore from list of stations. If you wish to remove a station, then send an email to the M3G team with the list of stations to be removed from your network together with the motivation why you wish to remove them.
A registered agency can define local or national networks in M3G , using the the “Managed Networks” section in the agency-specific section, available after login.
When defining a new network, you need to provide the following information:
  • the network abbreviation (must be unique throughout M3G)
  • the network name
  • the name of the agency that is responsible to include stations in the network (with a primary and secondary contact). The agency name is selected from a list of agencies that the user has set up already set up in M3G. This can be the user agency or another agency that has been defined as associated agency.
  • the DOI associated with the network
After the definition of the networks, a registered agency can associate each of its stations with one (or more) of the local/national networks that have been setup in M3G. For that purpose, the networks defined by all the M3G users can be selected.
International and virtual networks can only be setup by the M3G administrator.
Site log
After login, go to the agency-specific section, click on "Stations" and then go to the “Station Overview” table. Click on one of the icons in the column “Update” for the station that you are considering and follow the instructions.
M3G can only validate site logs for stations that are proposed to at least one of the international networks (EPN, EPN densification, or EPOS) that M3G is serving. The reason is that M3G needs to know which metadata validation rules it has to apply. To attribute your station to a international network, login, goto “Stations” (in the agency-specific section available after login) and click on “Edit networks”. Once the new page loads, propose the station to at least one international network.
In order to comply with GDPR, M3G is linking all the agency/contact information in the site logs with the information entered in "User Agency" and "Associated Agencies" in the agency-specific section of M3G.
  • Reponsible agency: For own stations, only your own agency can be selected in the site log. For third party stations, one of the associated agencies can be selected.
  • On-Site, Point of Contact Agency: Your own agency or one of the associated agencies can be selected.
  • The primary and secondary contacts can be selected from the predefined contacts in the selected agency. If the contact you wish to use is not in the list, then click on the last item in the dropdown menu "Add contact to profile" and complete the information of the new contact.
  • Login into M3G and go to "User Agency" in the agency-specific section
  • Click on "Modify" near the contact with new phone number
  • Change the phone number and save
  • The site logs of all stations listend under "Used in" will be updated
In the present version of M3G, site log updates can only be done by inserting the information on line in the Site log form. The reason for this choice is twofold:
  • GeodesyML: The M3G database is GeodesyML-compliant and GeodesyML metadata contains the full history of all what was done with the site log (e.g. when a site log section was deleted and replaced by another one, then also the deleted sections are kept in GeodesyML). Uploading a full site log for a station where we already have metadata in our GeodesyML-compliant database will presently cause a loss of the historical information in the database.
  • GDPR: To allow contact persons to decide if they agree to make their personal data publicaly available or not, M3G manages the permission/rejection of each contact person in a central database separately from the site logs. The permission/rejection is however applied to each of the site log where this contact person is mentioned. To link the site log with the centralised GDPR information, it is necessary to check all the contacts in the site log when the site log is updated the first time in M3G. This has to be done just once for each contact used in the site logs.
Edit, validate and submit your site log changes in M3G. After the submission, save your site log to your local disk. Go to the IGS Site Log Manager and upload the site log that you just saved.
The source of the problem is that station is known in M3G as a station that is owned by your agency. Therefore the site log can only indicate your own agency as responsible agency.
If your own agency is not the owner of station, then you will have tell M3G that the station is a third party station.
This can be done by doing the following steps:
First you need to insert the information on the owner agency in the your user profile. You can do that by:
  • Log in to M3G and select "Associated Agency" in to your agency menu
  • Click on the + (top right) of the table, enter the information for the agency owning the station, and save
Then you need to indicate that the station is a third party station and change the agency information. This is done by
  • Go again to the your agency menu, then "Stations" submenu and select "Edit agency information". In that table activate "Third party station" for the station, indicate the responsible agency (the agenc of the station owner that you just entered as an associated agency), contact info (at the agency of the station owner) and on site point of contact (probably your own agency). Save.
Personal data
M3G does not require any personal data. It needs however contact information for the agencies that are registered or set up in M3G. This contact information is entered in M3G by the registered agencies themselves (through the “User agency” and “Associated Agencies” submenus in the agency-specific section). The agencies can decide themselves to only use generic contact information (e.g. email aliases pointing to a team) instead of personal data. Mandatory information are the agency name (and abbreviation), address, name of the team (or person) and its email.
Please check ROBs general privacy policy and the specific Privacy policy of M3G. M3G manages the personal data centrally in order to comply with the EU General Data Protection Regulation (GDPR). Each of the contact persons that is entered in M3G will be asked by email if he/she agrees that his/her contact information is made publicly available without restrictions. If the person declines, then his contact information will not be exported (in e.g. site logs) and will be replaced by the general contact information of his/her agency (if available).
Someone has entered your personal contact information in M3G. M3G now asks you if you agree that M3G makes this information publicly available without restrictions. As long as you do not reply to this email, M3G will continue sending you emails. If you decline the request to publicly make available your personal data, then M3G will remove your personal data from all the metadata it makes publicly available and replace it with general agency contact information.