The Instrument Operations and Calibration System for TerraSAR-X

Abstract – The paper provides an overview about the System Engineering and Calibrations Segment (SEC), one part of the TerraSAR-X Ground Segment. SEC is in charge to build up and to operate the Instrument Operations and Calibration Segment (IOCS) in the frame of the whole TS-X Ground Segment, as well as for the SAR System Engineering. The IOCS consists of three sections, the Operations, Calibration and the Verification Section. SAR System Engineering provides the SAR know how to build up the IOCS system and includes Instrument Shadow Engineering, SAR System Performance Analysis and the transformation of SAR instrument characteristics into the TerraSAR-X ground segment. The tasks of the Instrument Operations Section are operation and monitoring of the SAR instrument with its different operational SAR modes Stripmap, ScanSAR and Spotlight. This task can be divided into: - generation of radar parameters for SAR data acquisition - generation of commands for SAR data acquisition - maintenance operations, e.g. generation of new instrument tables - contingency operations The prior task of Instrument Operations is the command generation for the planned data takes. Depending on the users selection of the SAR mode and the region to be covered, the radar parameters have to be calculated and the required instrument settings have to be generated. The Calibration Section has to guarantee the quality of the SAR products. The Calibration Section in the IOCS includes the functions: - internal calibration, - external calibration, - antenna pattern determination, - polarimetric calibration - noise characterization and the coordination of these tasks. The Verification Section has to ensure the correct in-orbit operation of the entire SAR system from data take instrument command generation to ground processing and has to technically release the SAR products. The complete SAR system verification is performed during the commissioning phase and at regular intervals during the mission. Specific verification activities can be triggered by faults and failures for trouble shooting. In order to perform this task the SAS System Verification is organized in the following functions: - Instrument Characterisation/Verification - SAR, Orbit and Auxiliary Product Characterisation/Verification - Long-term System Monitoring - Data Take Verification