Bernese GPS Software Version 5.0 - Bernese GNSS Software

5. Preparation of Earth Orientation, GNSS Orbit, and Satellite Clock Information
a list of GPS RINEX navigation files or a list of GLONASS RINEX navigation files. A
third possibility is to merge GLONASS and GPS RINEX navigation message files before
conversion. In this case it is recommended to process one pair of files in one program run.
Each input file (or pair of input files) will be converted into one output precise file.
In the resulting SP3 file the Earth-fixed positions of each satellite and its clock values
are stored in time intervals specified by the user. Normally a time interval of 15 minutes
is appropriate. The program checks the broadcast information for plausibility using the
criteria explained in Section 5.3.3.
The program RXNPRE allows to exclude GLONASS satellites showing a shift in the navigation
messages (e.g., due to a maneuver) from being written to the output precise orbit
file. Shifted GPS satellites are skipped in any case (see Section 5.3.3).
In order to process GPS and GLONASS data simultaneously, the orbit and clock information
needs to refer to the same reference system and to the same time scale. The GLONASS
broadcast ephemerides are therefore transformed to ITRF and GPS system time. For the
transition from PZ–90 (GLONASS reference system) to WGS–84 (GPS reference system
which is consistent with the parameters of the ITRS), a rotation of −334.5 mas around
the Z–axis is currently applied to the positions of the GLONASS satellites, see [Habrich,
1999] and [Ineichen et al., 2000]. The transformation values for the transition from PZ–90
to WGS–84 (resp. ITRF) have to be specified in file ${X}/GEN/DATUM.
After having transformed the broadcast RINEX files into SP3 format a standard orbit file in
Bernese format may be created using programs PRETAB (”Menu>Orbits/EOP>Create tabular orbits”)
and ORBGEN (”Menu>Orbits/EOP>Create standard orbits”). The procedure is the same as described
in Section 5.4).
For more information about the computation of GLONASS satellite positions using broadcast
ephemerides we refer to [Habrich, 1999].
5.3.2 Alternative Procedure for GPS
For the introduction of GPS broadcast navigation messages into the Bernese GPS Software
an alternative way is available which represents the standard for earlier versions of the
software and is contained in Version 5.0 for assuring backward compatibility: GPS RINEX
navigation messages may be converted into the internal broadcast format (default extension
BRD, see Section 22.7.1) using the program RXNBV3 (”Menu>RINEX>Import RINEX to Bernese format
>Navigation files”, description in Section 4.3). This file format may only hold broadcast messages
for GPS and not for GLONASS.
Let us mention that it is easy to edit the Bernese broadcast files with any text editor: files
may be concatenated, separated, and messages deleted. In this context it is important to
know that the messages need not be sorted according to satellites or time. The message
number which is given for each message is ignored by the access routine.
Bernese broadcast messages may be checked for inconsistencies using the program
BRDTST (”Menu>Orbits/EOP>Broadcast orbits>Check broadcast orbits”) (see following section). Program
BRDTAB (”Menu>Orbits/EOP>Broadcast orbits>Create tabular orbits”) must then be used to transform
the orbit information from the broadcast message into a set of tabular ephemerides in the
inertial system (we recommend to use the system J2000.0, exclusively). You will have to use
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