  1.  NAME

  gps - Compare position from different navigation devices

  2.  USAGE

  gps

  3.  DESCRIPTION

  This Matlab script reads navigation data from two different files,
  assuming that these result from two different navigation devices.
  Typically, this could be the navigation positions stored in a CODAS
  database, and an external GPS device.

  Input files must have the following columns:

  1. Time in decimal days

  2. Longitude in degrees

  3. Latitude in degrees

  This script is quite crude and could be improved easily.

  4.  PARAMETERS

  The following parameters must be edited:

     year_base
        Base year used in input files.

     nav_file
        Name of first navigation file.

     gps_file
        Name of second GPS data file.

     avg_time
        Ensemble average time in seconds. This parameter is used to find
        common positions and gaps between both input files.

     plot_title
        Title for plot.

     note
        Additionnal string to print on the plot.

  5.  FILES

  o  gps.ps

  6.  AUTHORS

  Pierre Jaccard, Geophysical Institute, University of Bergen, 1999

