Airborne Bistatic SAR Imaging Algorithm And Parameter Estimation Method

Airborne Bistatic Synthetic Aperture Radar (Bi-SAR) is a kind of SAR systerm whose transmitter and receiver are located on different airplanes as their platforms. It has the advantages of long detecting distance, capability of countering vulnerability, high security, ability of obtaining rich information etc., so the theoretical and experimental researches of Bistatic SAR are actively carried out in many countries and institutions.With the characteristi of separated transmitter and receiver, there will be many technic problems in system design and signal processing. The geometrical models will be more various and echo signals will be more complex. Then the technic problems such as imaging algorithms, Doppler parameters estimation, and synchronization and so on need to be solved. The main work of this thesis is shown as follows:1. Research on different geometrical models of the airborne Bi-SAR. The characteristics of echo model and Doppler characteristics are analysed. The relationship between the resolution and flight situations is discussed.2. The Bi-SAR Range-Doppler (RD) algorithm is researched, and the improved RD algorithms: Second Range Compression (SRC) algorithm amd Squint Imaging Mdoel (SIM) algorithm are used in the situations of squint model or the base line angle which is not zero. The applicabilitys of RD algorithm and its improved algorithms are verified through simulation experiments.3. Bi-SAR RD algorithm and its improved algorithms are used to process the experimental data of Bi-SAR flight experiment. The Bi-SAR images used these algorithms are generated sucessfully. The method based on Radon transform is shown to compensate the PRF linear synchronization error of the experimental data during the ex-processing.4. The Bi-SAR Doppler center estimation algorithms are studied in both time domain and frequency domain. The results of simulation are shown to analyse the advantage and limitation of each algorithm.5. The Bi-SAR autofocus algorithms are studied and used to process the experimental data of airborn bistatic SAR flight experiment. Their applicabilitys are verified under the condition of parallel flight model. The advantages and limitations of these algorithms are discussed finally.