Bernese GPS Software Version 5.0 - Bernese GNSS Software

10. Station Coordinates and Velocities
then refer to the middle epoch of the appearance of the station unless a different epoch is
explicitly demanded (option “Reference epoch for station coordinates” in panel “ADDNEQ2 3.1:
Options 1”).
When combining several normal equation systems, consistency is of utmost importance. If
the option “Notify station inconsistencies between NEQs” in panel “ADDNEQ2 3.2: Options 2” is
enabled, ADDNEQ2 reports all station equipment changes occurring in the processed time
span.
Station inconsistencies:
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Station First obs. epoch Last obs. epoch Receiver type Antenna type ...
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AUCK 50209M001 2005-10-08 00:00:00 2005-10-29 23:59:30 ASHTECH Z-XII3 ASH701945C_M ...
AUCK 50209M001 2005-10-30 00:00:00 2005-11-27 23:59:30 TRIMBLE NETRS TRM41249.00 ...
...
It should be carefully considered whether it is still valid to combine station coordinates
before and after a reported event. E.g., a receiver change is usually harmless whereas an
antenna change may cause a jump in the coordinates.
In the example above a completely new equipment has been installed at the station and
a jump in the coordinate time series may result. The station may be renamed (e.g., to
AUCK 50209M001B) and treated as a completely new station as of the point of equipment
change (see Section 10.3.5). ADDNEQ2 will then estimate two sets of coordinates, one for
station AUCK 50209M001 with the old equipment and one for AUCK 50209M001B with the
new equipment. By comparing these two coordinate sets it can be decided if the station can
still be combined despite the changes (the renaming can be undone in that case).
Apart from station equipment inconsistencies, the coordinate repeatabilities should be carefully
monitored. Jumps or outliers will most certainly degrade the quality of the results, the
more so if a reference station is affected. After computing the combined solution, program
ADDNEQ2 rereads each input NEQ and processes it individually with the same options if
“Compute and compare individual solutions” (see panel in Figure 9.6) is enabled.
Coordinate residuals of the individual solutions with respect to the combined solution are
computed in north, east, up and are reported in the output. In addition, they may be
written to a separate file specified in “Station residuals” in panel “ADDNEQ2 2: Output Files”.
The residuals allow to identify problems for individual stations or in individual input NEQs.
Because the geodetic datum for each individual solution is defined in the same way as for the
combined solution, residuals have to be interpreted carefully if the set of reference stations
changes from solution to solution or if solutions contain no reference stations at all.
The first two columns in the program output file (see Figure 10.3) give the first four characters
of the station name and the component. The third column gives the repeatability RMS
and the following columns the residuals for each input normal equation file. Values are given
in millimeters. Repeatability RMS values for each station may also be written to a “Weekly
summary file” if a filename is specified in the corresponding field in panel “ADDNEQ2 2: Output
Files”.
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