I wanted to share with you a bit more information regarding NAV file handling in Trimble Positions and why things may look different from PFO/GPSA.
With increasing numbers of satellite systems and base data providers, the task of managing base file URL address templates has become more complex. To better accommodate multiple GNSS systems (GPS, GLONASS etc…) the Trimble Positions Desktop addin allows users to associate up to three URL templates with a single base station.
During post processing the files referenced in the URL templates are downloaded and the Positions Desktop addin extracts the observation and navigation files before passing them to the differential correction engine.
- Observation files contain raw satellite measurements and are in Rinex or Dat formats.
- Navigation files contain satellite ephemeris data. This data is stored in separate Rinex files for GPS and GLONASS systems. Dat files contain both observations and ephemeris data.
If base files downloaded from a URL built from the “Base File Address Format” template do not contain ephemeris data, then “Nav File Address Formats” must be specified to reference files that contain GPS (and GLONASS, if required) navigation files. Most base station definitions provided by cbs_list.csv files will contain required address formats. You may add additional address formats if required. You may also use well-known sources of navigation data (e.g., ftp://garner.ucsd.edu/pub/nav/%YYYY%/%DDDDD%/auto%DDDDD%0.%YY%n.Z).