NATIONAL REPORT OF THE FEDERAL REPUBLIC OF ... - IAG Office

118 Commission 4 – Positioning and Applications
GLONASS
Since GPS week 1300 (December 2004) the weekly
GLONASS precise orbit solution of BKG is part of the
official IGS combination solution, together with ESA’s
results of orbit computation, the results obtained by the
University of Berne, and results of the “Mission Control
Centre“, in Moscow (both SLR and microwave solutions).
The combined IGS-GLONASS orbits are provided by the
“GeoForschungsZentrum Potsdam”.
Since April 2006 the GLONASS satellite orbits are computed
by means of the new Version 5.0 of the Bernese GPS
software. Utilization of the new software is a prerequisite
for the fulfilment of international standards in the field of
GNSS data analysis, which includes e.g. introduction of
the new reference frame ITRF2005 and the correction of
absolute instead of relative antenna phase-centre variations.
Through the new version the computing time could be
reduced by ca. 25 percent given that now possibilities of
parallelization of processes are used. The automated processing
components now run clearly more stably, whereby
it has become possible to perform the daily solutions
automatically already during night time and to do only the
combination of daily to three-day orbit arcs manually. With
the application of the new software version importance was
primarily attached to the reproducibility of results as
compared with the respective previous version. The IGS
performed some important change in the analysis strategy
with the beginning of week 1400, e.g., the switch from
ITRF2000 to ITRF2005 and from relative antenna phase
centre variations (PCVs) to absolute PCVs. These changes
were applied to the GLONASS analysis at the same time.
EUREF GNSS Permanent Network
Work on the European Reference Network EPN includes
the computation of a BKG solution for the purpose of a subnetwork,
the combination of the coordinate solutions and
the combination of the troposphere signal path delay of all
sub-networks of the 16 analysis centres of the EPN. The
activities mentioned last are done on a weekly basis. The
BKG solution as one of the solutions of the EPN analysis
centres is generated in the course of the common analysis
of the GREF and EPN stations and comprises altogether
approx. 90 stations.
The upgrade to Bernese GPS Software Version 5.0, introduction
of ITR2005 and switch to absolute PCVs were the
most essential innovation with regard to the combination
of coordinate solutions. The new module ADDNEQ2 for
the combination of the normal equations requires a change
in strategy. Now the coordinates are introduced as observations.
Further, first efforts have been started to develop
a new scheme for the weighting of the single solutions of
the different EPN analysis centres.
The COST Action 716 “Exploitation of ground based GPS
for climate and numerical weather prediction application“
ceased in spring 2004 after duration of five and a half years
with the completion of an extensive final report. As a
follow-up project both to this project as well as to other EU
projects, as e.g. TOUGH and MAGIC, the project “The
EUMETNET GPS Water Vapour Programme“ (E-GVAP)
was initiated by some of the participating countries within
the frame of EUMETNET, which is a conference grouping
20 European national meteorological services. Unfortunately,
the Federal Republic of Germany has not joined this
project until now. The near real-time solutions computed
by BKG can nevertheless still be contributed to the analytical
part of the project. The number of stations evaluated
by BKG on a regular basis was in the reporting period
increased from 80 to ca 120. On the one hand, the new
EPN-stations were taken into account, and on the other
hand further GREF stations were integrated.
German Permanent GNSS Networks
The GREF national reference network of the BKG has been
further extended to an integrated real-time network. This
extension consists of replacing the observation stations with
combined GPS/GLONASS receivers and implementing the
data transmission in real-time. It has been started to create
local security networks for the GREF stations with terrestrial
measurements. The extension of GREF also includes
the combination of the geometric satellite positioning
process with dynamic methods of height determination
and/or gravity measurements. Therefore, there are also
some stations located close to level measuring stations,
geophysical observatories or stations of the German gravity
reference network.
The geodetic reference network GREF presently comprises
22 real-time GNSS stations. The data of most stations are
transferred via DSL Internet connection to the central office
in Frankfurt, where they are processed by means of the
networking software EuroNet of Euronik. Pseudo-range
corrections are computed for virtual stations, evenly
distributed over the territory of the Federal Republic, and
transmitted over the Internet using the NTRIP protocol. The
service includes a comprehensive monitoring and backup
concept that guarantees the availability and quality of the
corrections, available in the RTCM 2.0 format.
The daily analysis of the GNSS observation data in the postprocessing
mode has been performed continuously with the
Bernese GPS Software Version 5.0. Besides the routine
evaluation beginning with GPS week 1400 the networks
are computed with absolute antenna phase eccentricities
and using the ITRF2005 / IGS05 reference frame. Test
evaluations including GLONASS observations and orbits
have been carried out and will be continued aiming to
include GLONASS in the regular analysis scheme.
SAPOS is the GNSS reference positioning system of the
German states, based on a widespread network of more than
250 permanently operated GPS reference stations. That
have been determined based on a diagnostic adjustment in
a homogenous, standard reference system of the European
Terrestrial Reference System 1989 (ETRS89).
SAPOS provides its customers with correction data in three
service areas of different accuracies using agreed transfer
media, data formats and fees. Real-time networking has
been introduced to enhance the reliability and accuracy of
the SAPOS HEPS real-time service. It solves the problem