Multipurpose GNSS network operations
 Hanssen, R. I.
 
 Norwegian Mapping Authority, Honefoss, Norway
 
 Different requirements from different networks have led to various types
 of
 equipment, sample rates, locations, data formats etc. Moving towards an
 integrated GNSS network, where the same equipment can be used for various
 purposes, will reduce investments and operational costs and improve the
 overall data quality.
 
 The backbone in such a scenario is the physical network or the "real"
 network consisting of geographically distributed sites with monuments,
 antennas, GNSS receivers, atomic clocks, met-sensors, etc. Each site is
 controlled by a computer, a multipurpose GNSS Station (MGS) which controls
 all the equipment, carries out quality control of the data and provides
 for
 the formatting and distribution of the data.
 
 The application network are networks specified by various customers and
 may
 be geodetic networks, navigation network, meteorological network, tide
 gauge
 networks, etc, using parts or the complete physical network.
 
 Each application network defines constraints to the physical network that
 it
 utilises. The requirements may vary from one application network to
 another.
 Each site has to be compliant to all of the application network
 requirements
 that use that particular site.
 
 The MGS has to fulfil a number of requirements like handling multiple GNSS
 receivers and formats, be able to send data from the same receiver in
 different data streams to the same data centre or the same data to several
 data centres, handle redundancy requirements, error recovery by e.g. using
 locally stored data, be able to do local monitoring or quality control of
 the data in real-time (or in fixed periods) and sending status reports or
 local integrity monitoring data (LIM) to the data centre.
 
 To achieve the necessary flexibility, a receiver independent format has to
 be used to distribute the data. The format has to be able to handle
 various
 types of data like GPS, GLONASS, GEO, meteorological, tide gauge, gravity
 data, and in a simple way be able to handle other future types. The format
 needs also to identify the site information for each data set that is
 produced.
 
 An example of how this may be handled is the Norwegian Permanent GNSS
 network, which is currently being deployed and which is based on the
 Satref
 technology using the GDIMS (GNSS Data Integrity Monitor System).