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Bernese GPS Software Version 5.0 - Bernese GNSS Software

Bernese GPS Software Version 5.0 - Bernese GNSS Software

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9.4 The Program ADDNEQ2<br />

Before pre-elimination<br />

After pre-elimination<br />

Figure 9.9: Option “Except for boundaries”.<br />

a priori values and constrained. It is possible to pre-eliminate the parameters from all<br />

normal equations except for those explicitly enumerated in the field “except for files”.<br />

This option allows it, e.g., to pre-eliminate the troposphere parameters of the first and<br />

last but not the middle of three daily normal equations by specifying the number ”2”.<br />

The troposphere results from the middle of a three-days solution are then written to<br />

the output file. Instead of a comma-delimited list also ”F” (first) and ”L” (last) may<br />

be used.<br />

AFTER STACKING: Parameters are pre-eliminated after reading of all input normal equation<br />

files and stacking of the parameters but before computing the solution and saving of<br />

the output normal equation. The parameters thus do not appear in the solution nor<br />

in the output normal equation or SINEX file. The option may be used to reduce the<br />

size of the resulting normal equation file.<br />

EXCEPT FOR BOUNDARIES: This interesting option can be applied to parameters describing<br />

a piece-wise linear function of time such as troposphere, global ionosphere, or Earth<br />

orientation parameters. It allows it to pre-eliminate all parameters before stacking<br />

except of those located at the beginning and at the end of the validity time interval of<br />

a normal equation (see Figure 9.9). As a consequence only parameters at the boundaries<br />

of the normal equations remain in the equations such that the parameters from<br />

successive normal equations can be stacked. Thus, contrary to the pre-elimination before<br />

stacking, e.g., the troposphere representation at the normal equation boundaries<br />

remains continuous.<br />

The operation is performed before stacking, i.e., individually for each input normal<br />

equation, and can be used to pre-eliminate a large number of parameters and nevertheless<br />

stack the parameters from normal equations adjacent in time. After the operation,<br />

isolated parameters at former normal equation boundaries remain in the resulting normal<br />

equation that may be removed by an additional ADDNEQ2 run. Option “except<br />

for files” allows it to exclude individual files from the pre-elimination in the same way<br />

as described above for option BEFORE STACKING above.<br />

DELETE: This option allows to fix parameters to their a priori value before eliminating<br />

them from the system. The option is preferable over a strong constraining followed<br />

by a pre-elimination because numerical problems caused by strong constraints are<br />

avoided. The operation is performed individually for each input normal equation after<br />

transformation of the parameters to new a priori values.<br />

<strong>Bernese</strong> <strong>GPS</strong> <strong>Software</strong> <strong>Version</strong> <strong>5.0</strong> Page 201

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