Abstract:

For synthetic aperture radar (SAR) is a coherent imaging system, signal based phase error correction, i.e., autofocus of SAR imagery is an important technique to improve the azimuth focusing quality. A variety of autofocus algorithms exist for generating high quality and high resolution SAR imagery.Among them, phase gradient autofocus (PGA) employs adjacent pulses of the range-compressed data as inputs to estimate the gradient of phase error at each position of the aperture, which is most widely used in practice for its efficient realization and excellent robustness. However, the precision of PGA would be severely affected by the signal-to-noise ratio of the input range lines. In order to solve this problem, a novel autofocus algorithm called phase error autofocus is presented, which could estimate the phase error directly by multiple-pulse vectors. Monte Carlo tests and real SAR data validate that the new approach could achieve better performance of autofocus in SAR images with lower levels of the execution time than PGA.