The gbin file name is based on the raw data.
The gbin is the gridded binary (gbin) file where all fields are gridded in time. The times in the instrument log file (e.g., raw/nb150/*.log) are the times that determine the grid, i.e., the Unix times of instrument pings. The Ashtech, GPS, seapath, heading, soundspeed are all interpolated to the Unix times of the pings and put into gbin files.
Now, the best time must be determined (decisions made to keep time monotonic increasing, and to track any other time corrections).
The results of this go into the files in the time subdir. *.tim.gbin has 3 rows containing: the Unix pingtimes, the “best” times, and the pc_sec-UTC difference. *.best.gbin is the gridded “best” values of position and heading, given that there are multiple sources for these.
The decision whether to use seapath or Ashtech, for example, or which is the primary navigation device, is NOT made by the program on the fly, but rather is set initially at the start of the cruise in procsetup_onship.py.