Gorobets O. Ground metrological accuracy assurance of space-born Earth Observation units

The thesis is devoted to the improving of methods of a synthetic aperture radar (SAR) vicarious calibration. Modern methods of the calibration are considered, their disadvantages are revealed, new approaches and algorithms are proposed as well. Research objects: radiophysical methods of a remote sensing, specified radar and infrared images of the Earth with shown special calibration devices or buildings which should be processed as digital signals, electromagnetic fields and waves in an external transponder system as well as their diffraction and interference. The purpose of the research is the development of vicarious calibration methods for space-based synthetic aperture radars as the most important component of quality assurance of Earth observation from space radars. Research Methods: applied electrodynamics methods, including geometric diffraction theory, probability theory and statistical radiophysics methods, computational mathematics, and experimental research methods as well. The experimental study of developed antennas has been carried out in an anechoic chamber with the appropriate equipment (microwave generator, VSWR meter, etc.). The theoretical modeling of these antennas, as well as statistical data analysis and signal processing algorithms have been performed as computer programs. Theoretical and practical results and their novelty. It is established for the first time the correlation between the point-target response width (number of pixels) with the reflector aperture dimensions, which is used to calibration. The advanced method for determining a SAR resolution which allows to use triangle corner reflectors of various sizes has been proposed as well. The mathematical model of the SAR output signal dependence versus the Radar Cross-section of reference reflectors, which are located on the scanned surface, is improved. The appropriate method for detailed evaluation of the transfer function and sensitivity of the SAR, which is based on more than hundred radar images of corner reflectors is developed as well. It is got Further development of building extraction task from grayscale images of an Earth surface. The algorithm doesn’t need to specify the typical object shape precisely and does not require a training dataset at all. It is proposed for the first time, the transponder with low-directional receiving and transmitting antennas and high gain microwave amplifiers as the high-performance point-target (reflector) for the ground test-site. The performance of the given transponder has been confirmed through the vicarious calibration campaign with the «TerraSar-X» spacecraft SAR. The obtained results and developed methods have been tested and put into practice during the vicarious calibration campaign of the "Condor-E" and "TerraSAR-X" space-born SARs. It has been done during the experimental testing and adoption stage of the calibration test site "Skripali" which has been supervised by the National Space Agency of Ukraine (NSAU) in 2012–2016.