Bernese GPS Software Version 5.0 - Bernese GNSS Software

15.3.2 Orbit Combination with ADDNEQ2
15.3 Orbit Improvement
Orbital parameters, if saved in normal equation files, can be manipulated by program
ADDNEQ2. It is in particular possible to change the constraining of parameters or to combine,
e.g., one-day arcs to longer arcs. The theory for this longarc combination may be found
in [Beutler et al., 1996].
Manipulation of orbital elements in ADDNEQ2 is initiated by supplying one or several normal
equation files that contain orbital parameters and to enable option “Orbital parameters”
in panel “ADDNEQ2 3.2: Options 2”. Additional panels are then activated that allow for the
definition of orbit-specific options. Figures 15.3 and 15.4 show the panels designed for specifying
the constraints for osculating elements as well as of dynamical and pseudo-stochastic
parameters.
Option “Long-arc computation” in the first panel enables long-arc combination of arcs if a
sequence of consecutive normal equation files is provided as input that contain orbital
parameters. The output is then a series of orbital element files. In addition, new pseudostochastic
parameters may be set up at the boundaries of the normal equation files with
option “Stochastic pulses at NEQ boundaries”. Combination of arcs at particular boundaries of
the normal equation files for specific satellites (e.g., for badly modelable orbits) may be suppressed
by supplying a satellite problem file containing corresponding splitting information
(see Section 22.4.6) as input file to ADDNEQ2.
If normal equation files of different sessions are combined (e.g., to compute long arcs), the
output of program ADDNEQ2 is a sequence of orbital element files, one for each input normal
equation file. In this case you have to use wildcard characters (either % or ?) in the output
file name in the field “Orbital elements”. The wildcard characters are then replaced by the
corresponding characters of the a priori standard orbit file name used to create the normal
equation files. To give an example, let us assume that the a priori standard orbit files used
to generate three 1-day normal equation files were named G1 06061.STD, G1 06062.STD,
Figure 15.3: Panel for defining orbit estimation options in ADDNEQ2.
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