Spaceborne Synthetic Aperture Radar (sar) Multi-mode System And Signal Processing

This thesis focuses on the multi-modes of space-borne synthetic aperture radar(SAR). Some problems in the system design were discussed and the related signalprocessing algorithms were developed, which were simulated and verified.Based on the principles of the space-bome ScanSAR, some impoat parametersto define the position of sub-swathes, the timing sequence of the system, the choice ofthe PRFs, the number of the samples of each burst and the SNR were investigated andwere regarded as the reference for the system general design. Some critical problemsabout ScanSAR system were discussed here, they were the number of the multi-look,the azimuth resolution and the range ambiguities. A new concept of the rangeambiguities was put forward, analyzed and verified. Base on the above discussion andcalculation, we put forward the modifled plan to the timer, the onboard MC and thedata format for the practical ScanSAR system.The ScanSAR data processing algorithms and its phase preserving characteristicswere studied and simulated. A new algorithm of SIFFT based on the modified R/DalgorithIn were discussed and simulated, and its output stitching and peak phasepreserving at the stitching points were discussed. Another algorithm of the modifiedSPECAN were also investigated and simulated. At last a pair of ERS1/2interferometric data utilized to simulating the burst-mode data was used to verify thephase preserving characteristics of the two algorithms and produced the desiredinterferograms.For the space-bome interferometric system, we analyzed its principle andinvestigated the characterishcs of its baseline, and the evaluating methods of thebaseline. In the view of the system decorrelation, we investigated the imagingconditions of the intederometric system, and analyzed its decorrelation sources and itsinduenees systematically, especially focused on the affect of the vedation of theSaellite orbit and satellite attitude on the Doppler spectan shift. Consequnty itgave the limitaion to the orbit parameters design and attitude pointing accuracy. Thecoherence coefficieni was ana1yzed to measure the system decorrelation. We alsodiscussed the new decorrelation sources of the ScanSAR interferometric system andthe limitation.The detailed INSAR data processing algorithIn was investigated and progranuned,especially the main steps, e.g. image pre-fllteT, image registration, illterferogramflatten and filter, and phase unwrapping. Wth ERSl/2 interferometric data, theprocessing software was verified and results showed that the methods we used arefeasible and the softWre is accuratC.