C Commands Summary

84 MiLLennium Command Descriptions Manual

FIX HEIGHT
This command configures the GPSCard in 2D mode with its height constrained to a given value. The command
would be used mainly in marine applications where height in relation to mean sea level may be considered to be
approximately constant. The height entered using this command is always referenced to the geoid (mean sea level,
see the PRTKA/B log in Chapter 4 and Appendix D) and uses units of metres. The FIX HEIGHT command will override
any previous FIX HEIGHT or FIX POSITION command and disables the output of differential corrections. The
receiver is capable of receiving and applying differential corrections from a reference station while FIX HEIGHT is
in effect. Use the UNFIX command to disable the current FIX command. No special solution status is reported in
the POSA/B or PRTKA/B logs for a 2 dimensional solution. This mode is detected by the standard deviation of the
height being 0.001m.
Syntax:
Example:
fix height 4.567
REMEMBER: Any error in the height estimate will cause an error in the position computed of the same order
of magnitude or higher. For example, if the user fixed height to zero and the antenna was installed on a 20
metre mast, the position can be expected to be in error by 10 to 60 metres, depending on the geometry of the
satellites. This command should only be used when absolutely necessary, i.e., when only three satellites are
visible.
NOTE: This command only affects pseudorange corrections and solutions, and so has no meaning within the
context of RT-2 and RT-20.
FIX HEIGHT height

[auto]

Syntax Range Value Description Default
FIX HEIGHT - Command unfix
height -1,000.0 to 20,000,000.0 Height in metres above mean sea level
auto The receiver will automatically fix the height at the last calculated value
if the number of satellites available is insufficient for a 3-D solution, to
provide a 2-D solution. Height calculation will resume when the number
of satellites available returns to 4 or more. The use of the UNFIX
command, or a different FIX command will disable the automatic fix
height mode. It is disabled by default.