Bernese GPS Software Version 5.0 - Bernese GNSS Software

5.6 Concatenation of Orbit Information and Orbit Comparison
files. Satellites with predicted positions will get lower priority. The priority may also be
controlled by the satellite-specific accuracy code specified in the precise file headers. The
program selects the satellite with lower accuracy code (better accuracy). The accuracy code
of satellites merged into the file may be set to zero (unknown). These options are particularly
useful to merge satellite positions extracted, e.g., from broadcast ephemeris files into
precise orbit files which do not contain all satellites. For details we refer to the help panel
of the program.
The program also allows to cut a precise file to a specific time interval, or session, selecting
the option “Concatenate files” and specifying a single input precise file. Because satellite
numbers in the output precise file are always stored in ascending order, the same option
allows to reorder the satellite entries. It is not recommended to concatenate successive
daily precise orbit files. They should be processed independently with program ORBGEN. If
concatenation is necessary, more than one precise file may be specified as input for program
ORBGEN.
5.6.2 Comparison of Satellite Orbits
Two programs are available to compare satellite orbits. The program ORBCMP (”Menu
>Orbits/EOP>Compare orbits>Precise orbits”) compares satellite orbits in different precise ephemeris
files. If you specify more than two files, the orbits from each file will be compared with the
orbits in all other files. A set of Helmert parameters between the orbits in different files
may be estimated. The comparison may be performed in the Earth-fixed or in the inertial
system. The precise ephemeris files are compared for orbit positions at common epochs.
The program STDDIF (”Menu>Orbits/EOP>Compare orbits>Standard orbits”) is used for study purposes
to create a table of coordinate differences of two standard orbit files. The coordinate
differences are listed in radial, along-track, and out-of-plane directions. Both programs are
very simple to use, the handling is fully explained in the corresponding help panels.
A third program, STDELE (”Menu>Orbits/EOP>Compare orbits>Osculating elements”), may be used to
compute orbit position differences at the middle epoch of the orbit overlap time interval.
The program provides differences of osculating elements, the position difference in radial,
along track and cross track directions, as well as the absolute values of the position and
velocity difference vectors. The program compares successive orbits if more than two input
orbit files are specified. Consult the on-line help for further information.
Bernese GPS Software Version 5.0 Page 99