The Techniques For Space-Borne Scan Interferometric Synthetic Aperture Radar System And Signal Processing

Spcace-borne Scan Interferometric Synthetic Aperture Radar (Scan-InSAR) is anew technique for wide swath elevation measurement. It is a combination of thewide swath property of ScanSAR and the elevation measurement ability ofInterferometric SAR. With the Scan-InSAR results, the elevation information of awide swath area can be obtained, which is greatly benefit to global topography; onthe other hand, monitoring the surface change of some area can be realized in shorterperiod. The Scan-InSAR system parameters and relative signal processing methodsof Scan-InSAR are studied in an all-round and systematical way in this dissertation.The main work and innovations of the dissertation are as follows:(1) Some imaging algorithms for ScanSAR mode are investigated, includingSPECAN algorithm, Full Aperture algorithm and Extended Chirp Scaling algorithm.The phase preserving properties are analyzed. Some aspects of the ECS algorithmfor ScanSAR mode are investigated deeply, such as the signal phase variation, theinfluence of range scaling function on the result and the ability of extending andshrinking image. The characteristics and applicable conditions of the threealgorithms are contrasted.(2) Interferometric SAR data processing methods are investigated. Animproved maximum spectrum peak co-registration method is proposed. The methoduse chirp-z transform and the adaptive variation of the estimation window width toreduce the computation load as well as ensure the estimation accuracy.Experimental results show that the method has lower computation load and it issuitable for low coherence data co-registration. (3) The characteristics of Scan-InSAR signal are investigated. The properties ofsignal Auto Correlation Function and Power Spectrum Density are derived in theory.The Azimuth Scan Pattern Synchronization (ASPS) is investigated deeply, includingthe origin, the influence on coherence and the estimation method, which is validatedwith real data; the influence of the azimuth miscoregistration on the coherence isderived.(4) The system parameters of Scan-InSAR are analyzed. The factors affectingphase errors are analyzed. The origins of azimuth spectrum shift in Scan-InSAR areanalyzed in detail, including Doppler Centroid difference, influence of azimuth slopeand ASPS. The elevation measurement accuracy of Scan-InSAR system is analyzed.The requirements of orbit maintenance and ASPS are brought forward. Therequirement of yaw steering for S-band ScanSAR system is analyzed in detail.(5) The Scan-InSAR data processing methods are investigated deeply. Aco-registration method called "mosaic fitting- separating interpolation" is proposedto fit for the discontinuous in azimuth direction of ScanSAR data; A flatten methodis proposed to resolve the problem of the irregular variation of the "zero Dopplertime" in the ASAR WSS data. The Scan-InSAR data processing scheme is proposed.