Bernese GPS Software Version 5.0 - Bernese GNSS Software

Comparison of Individual Solutions:
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10.3 Coordinate and Velocity Estimation in Practice
BRUS N 0.49 -0.26 0.11 -0.45 -0.46 -0.26 0.47 0.79
BRUS E 0.49 -0.38 0.24 0.56 0.34 0.33 -0.03 -0.83
BRUS U 2.53 -2.39 -2.82 -1.85 1.54 3.16 2.92 0.74
ZIMM N 0.37 0.67 0.11 -0.18 -0.22 -0.33 -0.30 0.29
ZIMM E 0.50 -0.50 -0.25 -0.23 -0.37 0.24 0.58 0.77
ZIMM U 2.91 -2.06 -3.87 -2.56 0.16 3.20 3.78 0.76
Figure 10.3: Coordinate residuals in the ADDNEQ2 program output file.
If option “Compute and compare individual solutions” in panel “ADDNEQ2 3.1: Options 1” is set to
HELMERT a seven-parameter Helmert transformation is applied to compare each individual
solution with the combined solution. The corresponding Helmert parameters are listed in
the program output file.
In panel “ADDNEQ2 4: Comparison of Individual Solutions” threshold values for residuals and for
repeatability RMS values may be specified as well as a minimum number of contributing
input normal equation files. These options allow it to automatically generate a list of stations
for which the coordinate comparison indicates anomalous behavior. If outliers are found
they are reported directly below the comparison output section. Enabling the options does,
however, not have any influence on the results but only notifies possible outliers in the
program output. It might be a good idea to repeat the ADDNEQ2 run and pre-eliminate
the misbehaving stations before stacking. This can easily be achieved by a corresponding
entry in the station information file.
10.3.4 Velocity Estimation
If the multi-session solution covers a reasonable long time interval, e.g., one year or more,
it is possible to estimate station velocities with ADDNEQ2. The technicalities of velocity
estimation are described in Section 9.3.8.1.
Velocity estimation is activated by the option “Set up station velocities” in panel “ADDNEQ2 3.1:
Options 1”. Estimated velocities are not automatically given in the geodetic datum defined for
the station positions. As a consequence the datum has to be defined separately for positions
and velocities. The corresponding panel “ADDNEQ2 6: Datum Definition for Station Velocities”
is similar to the coordinate related panel and offers the same options (cf. Figure 10.1).
It is recommended to introduce a priori velocities (option “Station velocities” in panel
“ADDNEQ2 1: Input Files”) and define the velocity datum using a no-net-translation condition
on the velocity vectors (sum of improvements constrained to zero) for the reference sites.
Alternatively, velocities may be tightly constrained if good a priori velocities are known.
For small networks and for not too large displacements in the considered time interval it is
possible to use a priori coordinates propagated to the middle epoch of the analyzed time
period, specify no a priori velocities, and constrain the velocity vector of one site. The estimated
velocities of the other sites then are relative to that specific site. In no case station
coordinates should be fixed if velocities are estimated.
Bernese GPS Software Version 5.0 Page 223