The directory rawnav contains the raw navigation collected
using a differential GPS system (Ashtech). These files represent the raw data
recorded on floppy disk aboard ship. The data are in NEMA format. WARNING:
These data have not been checked for errors. Use
To aid viewing of the original raw navigation data, each data entry was reformatted
(removing the NEMA codes) by filtering the raw data files through a UNIX awk script..
Every navigation fix from the original data has been preserved however.
The navigation is stored in ASCII files using six fields separated by tabs, with
each file representing a separate julian day (i.e. feb04.txt). Navigation fixes
are at 10 second intervals. The start and end of each line is marked within each
reformatted navigation file. These files are located in the rawnav sub-directory
of the nav directory.
- Field 1: date and time (julian day:hour (GMT):minute:second)
- Field 2: Latitude (decimal degrees)
- Field 3: Longitude (decimal degrees)
- Field 4: Speed (in knots, computed from the navigation)
- Field 5: Heading (in degrees, computed from the navigation, i.e.
course made good)
- Field 6: Water Depth (derived from a Furuno digital echo sounder).
Depths are in meters, but have not been corrected for the depth of the transducer,
which was about 1 m below the sea surface