Bernese GPS Software Version 5.0 - Bernese GNSS Software

9.4 The Program ADDNEQ2
Before pre-elimination
After pre-elimination
Figure 9.9: Option “Except for boundaries”.
a priori values and constrained. It is possible to pre-eliminate the parameters from all
normal equations except for those explicitly enumerated in the field “except for files”.
This option allows it, e.g., to pre-eliminate the troposphere parameters of the first and
last but not the middle of three daily normal equations by specifying the number ”2”.
The troposphere results from the middle of a three-days solution are then written to
the output file. Instead of a comma-delimited list also ”F” (first) and ”L” (last) may
be used.
AFTER STACKING: Parameters are pre-eliminated after reading of all input normal equation
files and stacking of the parameters but before computing the solution and saving of
the output normal equation. The parameters thus do not appear in the solution nor
in the output normal equation or SINEX file. The option may be used to reduce the
size of the resulting normal equation file.
EXCEPT FOR BOUNDARIES: This interesting option can be applied to parameters describing
a piece-wise linear function of time such as troposphere, global ionosphere, or Earth
orientation parameters. It allows it to pre-eliminate all parameters before stacking
except of those located at the beginning and at the end of the validity time interval of
a normal equation (see Figure 9.9). As a consequence only parameters at the boundaries
of the normal equations remain in the equations such that the parameters from
successive normal equations can be stacked. Thus, contrary to the pre-elimination before
stacking, e.g., the troposphere representation at the normal equation boundaries
remains continuous.
The operation is performed before stacking, i.e., individually for each input normal
equation, and can be used to pre-eliminate a large number of parameters and nevertheless
stack the parameters from normal equations adjacent in time. After the operation,
isolated parameters at former normal equation boundaries remain in the resulting normal
equation that may be removed by an additional ADDNEQ2 run. Option “except
for files” allows it to exclude individual files from the pre-elimination in the same way
as described above for option BEFORE STACKING above.
DELETE: This option allows to fix parameters to their a priori value before eliminating
them from the system. The option is preferable over a strong constraining followed
by a pre-elimination because numerical problems caused by strong constraints are
avoided. The operation is performed individually for each input normal equation after
transformation of the parameters to new a priori values.
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