Research On Synthetic Aperture Radar Imaging

With the increasing military and civilian demands, modern high-tech has transformed to both information and intelligence. In this case, the all-round and three-dimensional reconnaissance means is the foundation of modern natural science and engineering technology. For radar, one of the basic functions is to find targets by target scattering of electromagnetic waves. It is a kind of modern high-tech system, which combines a variety of scientific and technological achievements.Synthetic Aperture Radar (SAR) is a high resolution microwave imaging radar. It can obtain higher distance resolution by launching large wideband signal, and can achieve higher azimuth resolution by synthetic aperture techniques. With the evolution of SAR and the extension of application areas, SAR is expected to be able to process not only steady targets, but also moving objects, and to estimate critical parameters. Interferometry Synthetic Aperture Radar (InSAR) technology is an important extension of synthetic aperture radar (SAR), it is a powerful tool to get large scale three-dimensional information, even to measure tiny changes of radar route accurately. Shuttle Radar Topography Mission (SRTM) has fully reflected the power of SAR and InSAR in obtaining the surface geometry information.In this paper, the basic principles, the imaging algorithm and motion compensation of SAR were discussed firstly. After that, the imaging principle and process of InSAR were discussed also. In addition, reviews of current research and application status were added to better recognize them.Firstly regarding the SAR imaging studies, based on the principle of synthetic aperture radar imaging, a high resolution implementation on both distance and azimuth was achieved. Meanwhile, the principle of chirp signal matching filter and pulse compression was studied. In addition, three classical imaging algorithms were summarized to clarify three different range migration situations:the traditional Range-Doppler (RD) algorithm, the improved Range-Doppler algorithm and the Chirp Scaling (CS) algorithm, respectively. A detailed principle explanation of each algorithm was given in this paper, as well as comparisons between each algorithm and concrete implementations. Then an estimation of Doppler chirp parameter was done via image shift (MD) algorithm, and finally the effectiveness of imaging motion was demonstrated by actual data imaging.Then regarding the InSAR imaging studies, the data processing of InSAR was mainly researched. We introduced the basic principles of InSAR altimeter, and analyzed the key factors which affect the InSAR measurement accuracy. In particular, techniques such as imaging registration, interferometry phase filtering and phase unwrapping of synthetic aperture radar signal processing were discussed in terms of their theoretical principles and related algorithms. At the end, a complete InSAR imaging simulation was done by experimental data.