Novatel OM-20000041 用户手册

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Commands Summary
MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1
97
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 meters. 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
or
fix height auto
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 meter mast, the position can be expected to be in error by 10 to 60 meters, 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
value
Syntax
Range Value
Description
Default
FIX HEIGHT
-
Command
unfix
value
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.