Star Machine Double-base Sar Imaging Algorithm Research

Spaceborne-Airborne Bistatic SAR (SA-BiSAR) is a kind of novel bistatic SARsystem, in which the transmitter and the receiver are mounted on the spacecraft andaircraft respectively. Because of its advantage of large imaging area, high SNR andgreat counter-countermeasure capability, recently SA-BiSAR becomes one of importantremote sensing application. In this thesis, the SA-BiSAR image formation algorithmbased on2D-PSP is studied. The main works are summarized as follows:1. The work modes of the SA-BiSAR system are introduced at first. Then, a groupof SA-BiSAR parameters are designed in the wide-beam mode, such as resolutions,swath width, imaging scene, imaging time, aperture time, PRF, SNR etc.2. The two-dimensional spectrum of the SA-BiSAR system is studied. The ELBF(Extened Loffeld’s Bistatic Formula) and2D-PSP (Two-Dimensional Principle ofStationary Phase) are introduced and analyzed. Moreover, the focusing precision of the2D-PSP is compared with the ELBF in different squint angle. The simulation resultsshow the2D-PSP is better than the ELBF.3. The frequency algorithms are dicussed thoroughly. Based on the spectrum of2D-PSP, Range-Doppler Algorithm (RDA) and Chirp-Scaling Algorithm (CSA) areimplemented to deal with space-variant BiSAR data. The simulation results demonstratethe validity of the algorithms. Moreover, the imaging results of the RD based on the2D-PSP are compared with the ELBF in the different parameters of squint angle. Itdemonstrates the focusing effect of RDA based on the2D-PSP is better.4. Considering the characteristics of the wavenumber-domain algorithm, awavenumber-domain algorithm based on the2D-PSP is proposed. The bistatic stoltmapping function is derived to align the range cell migration of SA-BiSAR data. Toimprove the focusing performance stolt intepolation, two-dimensional nonuniform fastFourier transform is derived to solve the nonuniform data mapping problem. In thedifferent squint angle, the numerical simulations are accomplished. The resultsdemonstrate the focusing performance of proposed wavenumber-domain(2D-PSP)algorithm is much better than wavenumber-domain(ELBF) algorithm. Finally, a simulation using distributed targets raw data is performed to validate the presentedalgorithm.