Bernese GPS Software Version 5.0 - Bernese GNSS Software

16.4 Estimation of Phase Center Corrections
SATELLIT.I05 in routine processing, updating your Bernese phase center eccentricity file
in a BPE process becomes indispensable in order to avoid aborting of your processing. The
main reason for that is to keep the satellite-specific antenna phase center corrections up to
date in your phase center file (e.g., with respect to new satellites), see Section 16.2.5.
As a nice side effect of such an update step, receiver antenna calibrations of added antenna/radome
combinations get automatically included in your Bernese phase center eccentricity
file. This obviously also includes indicated enlargement of your phase center file (after
a change of your station information file). It is worth mentioning that the phase center model
identifier gets automatically updated, ensuring a proper phase center model declaration in
your SINEX results (see Section 16.2.6). For this purpose, the files I01.ATX and I05.ATX
are maintained at CODE (in terms of the GPS/GLONASS satellite constellation) and regularly
posted to the addresses mentioned above. Both files are consistent to igs 01.atx and
igs05 wwww.atx (e.g., igs05 1402.atx), respectively, which are maintained at the IGS CB
(in terms of the IGS receiver network).
16.4 Estimation of Phase Center Corrections
The Bernese GPS Software provides the possibility to estimate the antenna phase center
offsets ∆r as well as the phase center variations ∆φ ′ (α,z) for both, receiver and satellite
antennas. The estimation of the parameters can be enabled in panel “GPSEST 5.1: Setup of
Parameters and Pre-Elimination 1” and “GPSEST 5.2: Setup of Parameters and Pre-Elimination 2”.
All four parameter types are highly correlated and cannot be estimated at the same time.
Note that the term ∆φ ′ (α,z) may be modified by an arbitrary constant ∆φ0 that corresponds
to a clock offset. When estimating the function ∆φ ′ (α,z) a singularity arises that
may be avoided, e.g., by a zero mean condition or by defining ∆φ ′ (α,0) = 0 (as the model
is provided by the IGS).
16.4.1 Estimation of Receiver Antenna Model Parameters
We refer to [Rothacher et al., 1995a] for details about the setup of a calibration campaign.
The receiver antenna calibration is performed in a local network where data from both
frequencies can individually be processed.
The first problem which has to be solved is how to determine the correct station positions
(ground truth). It is, e.g., possible to use the following approach: let us assume that the
calibration campaign consists of two sessions (the sessions should be quite long – at least
24 hours) and let us further assume that only two antennas were present. We select one
antenna as reference. We want to estimate the antenna phase center variations ∆φ ′ (α,z).
Processing the first session (without estimating antenna phase center offsets and/or variations)
the resulting relative position of both stations is corrupted by an unknown mean
antenna phase center offset ∆r. If we exchange both antennas before the second session,
the result of the second session is corrupted by −∆r. The mean position (stemming from
processing both sessions together) is correct. Now, it is possible to fix the station positions
and to compute the coefficients defining the function ∆φ ′ (α,z).
Bernese GPS Software Version 5.0 Page 341