Flexible methods for generation of GNSS navigation data

The disclosed technology teaches simulating new satellite messages for a GNSS simulation, providing a configuration file and programming script file, neither of which is pre-compiled into GNSS simulation code, that specify format for a message for a satellite and message format combination not yet operational or not yet compiled into the GNSS simulation code. Included is reading and applying the configuration file and running a script from the programming script file to generate navigation data for simulating positioning messages during the GNSS simulation and using the navigation data for simulating positioning signals during the GNSS simulation and testing of a GNSS receiver against the satellite and message format combination. The disclosed technology also teaches determining message format and values to use when simulating position signals by combining field format and field data values from a combination of the configuration files, almanac, ephemeris and related data, and the programming script files.