Instruction manual

Understanding CPD Page 37
Understanding
System Performance Optimization
CPD Solution Parameters
Table 3.2 lists the commands which are provided for optimizing the CPD operations.
Ambiguity Fix: $PASHS,CPD,AFP
The ambiguity fixing parameter can be set to different confidence levels between 95.0
and 99.9. Higher confidence levels result in longer search times but increase the
reliability of the ambiguity fixed solution.
The ambiguity fix mode can be set from 1 to 5. The default setting of 4 is
recommended for most static and kinematic surveying applications. Setting the mode
to 5 results in the highest reliability that the ambiguities are fixed correctly, but also
results in a longer time to resolve the ambiguities and give the fixed solution. Setting
the mode to 2 or 3 decreases the time to solve the ambiguities and give the fixed
solution, but also increases the chances that the ambiguities are fixed incorrectly.
Setting the mode to 1 results in the shortest time to resolve the ambiguities; however,
mode 1 also has the highest chance (typically 2.4%) that the ambiguities are fixed
incorrectly.
shows the test results for over 12,000 ambiguity fix test performed by Ashtech at
various baseline lengths up to nine kilometers. These test results indicate that at the
default setting (mode 4), the typical time to resolve the ambiguities is 60 seconds,
with a reliability of 99.9% At the fastest setting (mode 1) the results indicate that the
typical time to resolve the ambiguities is five seconds, with a reliability of 97.6%.
Table 3.2: CPD optimization commands
Command Description
$PASHS,CPD,AFP Selects the ambiguity fixing parameters
$PASHS,CPD,DYN Changes the Rover dynamics
$PASHS,CPD,FST Turns on/off fast CPD operation
$PASHS,CPD,MTP Changes the expected multipath in the system
$PASHS,CPD,PED Changes the DBEN output interval
$PASHS,CPD,PER Changes the CPD update interval
$PASHS,CPD,RST Reinitializes the CPD operation
$PASHS,CPD,UBS Selects which base station coordinates to use.