Data Modelling

GNSS (Global Navigation Satellite System) is a satellite system that is used to pinpoint the geographic location of a user’s receiver anywhere in the world. DGNSS (Differential GNSS) is an enhancement to GNSS that provides improved location accuracy and integrity.

DGNSS uses a network of fixed, ground-based reference stations to broadcast the difference between the positions indicated by the GNSS (satellite) systems and the known fixed positions. These stations broadcast the difference between the measured satellite pseudoranges and actual (internally computed) pseudoranges, and receiver stations may correct their pseudoranges by the same amount. The digital correction signal is typically broadcast over ground-based transmitters with ranges up to 250 km.

The DGNSS Station Almanac is a document published and maintained by IALA, which contains information about the worldwide DGNSS stations. The DGNSS Station Almanac Product Specification provides a common structure for the exchange of information about DGNSS stations. The product contains the station name, identification numbers of reference stations and transmitting station, positions, nominal range, operation status, transmitted message types, frequency, bit rate, remarks related to a DGNSS station.

The Product Specification can be used to exchange DGNSS station information in a consistent form between IALA, Lighthouse Authorities, Hydrographic Offices and other organizations (to include commercial and professional agencies). This information can also be provided as a document converted from the dataset