Research On Displaced Phase Centers Multi-band Hrws Sar Technology

Modern earth observation missions put forward higher and higher request on the capability of high resolution and wide swath (HRWS) imaging for spaceborne synthetic aperture radar (SAR). Conventional SAR systems such as Stripmap SAR, ScanSAR and Spotlight SAR systems are not capable of fulfilling the increasing demands for improved spatial resolution and wider swath coverage. As a single-output multiple-input SAR system, displaced phase centers multiple-azimuth-beam (DPCMAB) system solving the inherent conflict between azimuth resolution and swath width, thus realizes continuous earth observation with excellent HRWS imaging capability. Range resolution depends on signal bandwidth, but spaceborne SAR systems still encounter great difficulties in generation, transmitting and other aspects of signal with so wide bandwidth. Synthetic bandwidth technology of stepped chirp signal achieves high range resolution by fusing the sub-band signal with smaller bandwidth, can reduce system burden remarkably.Forming a multiple-input multiple-output (MIMO) SAR system by combining DPCMAB and concurrent-sub-band of stepped chirp signal, wide swath as well as high resolution on the two dimension can be achieved simultaneously. This thesis focuses on such problems of this system as systematical principal, performance analysis, signal processing ,error analysis and so on. The principal and signal processing theory of DPCMAB system is interpreted in Chapter 2, after simulation and analysis to critical errors, dominant scatter based algorithm and joint iterative self-tuning algorithm used to estimation of array errors are simulated and analyzed. Influence of systematic parameters on signal reconstruction performance is analyzed in Chapter 3, based on the flexible beam forming capability of active phased array antenna, adaptive array configuration approach used to optimizing signal reconstruction performance is expatiated. The principal and signal processing theory of concurrent-sub-band system is studied in chapter 4, the influence of incomplete orthodoxy of sub-band signal is analyzed, up and down chirp modulated stepped chirp signal is used to suppress the peak level of the unwanted virtual image and it's validity and limitation is presented,dominant scatter based error compensation approach is interpreted too. In the last Chapter, a kind of MIMO HRWS SAR combining DPCMAB and concurrent-sub-band modes is introduced, research work such as echo data generation, data fusing and SAR imaging are implemented, simulation work demonstrates the excellent capability of 2D high resolution imaging of the new SAR system.