Geometric calibration of across track interferometry data

    Project Details


    In order to achieve a high geodetic fidelity when using across track interferometric SAR systems operationally, calibration procedures must be applied. Inaccurate navigation data and system parameters as well as system imperfections must be accounted for. The latter contributes errors up to 10 meters to the terrain elevation maps generated from EMISAR data.
    In 1996 a procedure estimating a calibration function from distributed targets with known elevation (e.g. a sea surface) was developed.
    In 1997 theoretical models describing the impact of key error contributors on the measured terrain elevation was derived and a parametric version of the above-mentioned calibration procedure was developed. This procedure was supplemented with an internal calibration and applied to EMISAR data. The stability of the estimated calibration parameters was examined in order to assess the general utility of the procedure.
    In 1998 the EMISAR sensor was improved at two points relating to interferometric calibration. Firstly, the internal calibration loop was extended right to the antenna ports thus covering a larger part of the system. Secondly, the isolation of the switch that allows the system to be operated in multiple modes was increased, thereby reducing one of the above-mentioned system imperfections.
    In 1999 a new calibration algorithm was developed. It is based on the difference between DEMs from two crossing tracks, and it does neither require a dedicated calibration scene (e.g. a nearby sea surface) nor sufficient system stability to make the calibration function stable from scene to scene.
    (Related projects - see:
    Effective start/end date26/04/199531/12/1999


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