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Eduardo Rodrigues Silva Filho "GNSS-based Position and Baseline Determination and Clock Synchronization of Multistatic SAR"
Donnerstag, 30. Januar 2020
14.00 h Großer Besprechungsraum HR, Gebäude 102
Multistatic constellations can offer various advantages for SAR remote sensing. These concepts are challenging to implement for a series of technical difficulties. The lack of synchronization, caused by the operation of transmitter and receiver with different master clocks, poses one of the fundamental operational problems, contaminating the phase signatures of the radar imaging and challenging its differential ranging accuracy. In addition, baseline accuracy of a few millimeters must achieved, preferably using data obtained from low-cost GNSS receivers. In this work, we evaluate a synchronization method based on GNSS navigation data and Precise-Orbit Determination. The method consists in using in each satellite the same oscillator for the master clock of the GNSS receiver and of the SAR payload, so that the relative time estimation obtained in the precise orbit determination can be used to synchronize the radar data in the post-processing. The simulations suggest the proposed approach is capable of delivering reliable estimates of phase errors in the absence of strong baseline velocity deviations and if multipath and other systematic errors are successfully suppressed or calibrated. In addition, we evaluate different configurations in an attempt to improve the individual baselines estimates by combining GNSS data from several satellites flying in close formation. In our preliminary studies we conclude that the individual baseline can potentially be improved by using intersatellite links and by implementing a consistency check by comparing the height biases between DEMs generated from different pairs of satellite.
The objective of the PolSAR-Ap project is to evaluate and demonstrate the importance of fully polarimetric synthetic aperture radar data for a wide range of remote sensing applications. An important component of the project is the development of a software tool and the compilation of a book. PolSAR-Ap is supported by the European Space Agency and coordinated by DLR-HR.
The German national TerraSAR-X satellite based on a public-private partnership agreement between DLR and EADS Astrium GmbH and planned for launch in October 2006, will be a SAR system with StripMap, ScanSAR and Spotlight mode, as well as several experimental modes like wide bandwidth operation, along track interferometry or right/left looking radar. The calibration group is responsible for the complete calibration of TerraSAR-X. In addition to the development and the integration of the calibration functions for TerraSAR-X, all calibration activities including the planning, the coordination and the execution of the campaigns during the commissioning phase will be performed by the group.
TerraSAR-X will be operated in a tandem orbit configuration with a second X-band SAR satellite, in order to generate a global Digital Elevation Model. A height calibration concept is under development.
Sentinel-1 is C-band SAR system as part of the ESA/EU GMES (Global Monitoring for Environment and Security) programme. As a member of an industrial consortium, the group is contributing with the calibration and verification concept to the Phase B1 study.
Under a contract to EADS Astrium Ltd. the group was responsible for the System Calibration and Verification Plan and the specification of the Instrument Calibration Segment for ESA’s TerraSAR-L phase B study.
The TRAMRAD project was established to study the potentials of airborne or spaceborne radar systems for the wide-area monitoring and control of road traffic. The goal is the definition of radar system concepts, which are able to provide wide area traffic data frequently for traffic monitoring or, in extended time intervals, for traffic planning.
New light materials for UCAVs (unmanned combat aerial vehicles) are under development (DLR, Institute of Composite Structures and Adaptive Systems, Braunschweig). Reflection attenuation measurements on several material samples in the microwave frequency range are performed by the signature group.
FFT (Fortschrittliche Flugkörper Technologien – Innovative Missile Technologies)
The influence of the complete propagation path between a target and the antenna of a radar seeking head mounted behind a missile radome is examined. Transmission attenuation measurements on several material samples in the microwave frequency range are performed.
The AMPER (Application of Multi-parameter Polarimetry in Environmental Remote sensing) project, funded by the EU from 2003 to 2005, was a network of 9 European partner organisations like Universities, Research Centres or private companies. The objectives of the project were, beside the research in the area of multi-parameter radar polarimetry, also the training, mobility of young researchers. Here, the Institute was responsible for the overall coordination of the project and for the research contributions performed in the field of modelling and in the comprehension of atmospheric effects and distortions on coherent polarimetric radar data. Furthermore, contributions were made in the field of polarimetric target decomposition theory.
The European project CARPE DIEM (Critical Assessment of available Radar Precipitation Estimation techniques and Development of Innovative approaches for Environmental Management) was related to the Energy, Environment and Sustainable Development Research Program of the fifth framework programme. Its objective was to improve the flood forecasting capabilities. The institute’s tasks comprised the exploitation of advanced radar capabilities to allow the enhanced assimilation of weather radar data from operational networks in hydrological and numerical weather prediction models.
ALOS PALSAR product verification
The Japanese ALOS satellite, launched by JAXA on 24 th January 2006, carries three instruments, one of them being the fully polarimetric L-band radar sensor PALSAR. Under a contract with ESA/ESRIN, the Institute has to assess the quality of ALOS/PALSAR products distributed by the European ADEN node during the commissioning phase of the instrument and to provide a set of algorithms for quality control throughout the mission lifetime.
The BMBF funded GITEWS (German-Indonesian Tsunami Early Warning System) project aims at the implementation of an effective Tsunami Early Warning System for the Indian Ocean, mainly off Indonesia, and integrates terrestrial seismological and geodetic observation networks with marine measurement techniques and satellite observations. The Institute's contribution is a study of current and future possibilities of Tsunami detection using ground-based or spaceborne radar sensors or the combination of such systems. The goal is to provide a comprehensive system concept by the end of 2008, which complements and refines today’s "conventional" methods.
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