A NOVEL ESTIMATION APPROACH OF DYNAMIC AND COUPLING BASELINE FOR DISTRIBUTED SATELLITE SAR

In distributed satellite synthetic aperture radar (DS-SAR), along-track and cross-track baselines couple with each other and change dynamically due to formation flying, which makes it difficult to estimate interferometric baseline accurately. To solve the problem, a novel high-precision baseline estimation approach based on interferometric phase is proposed. By modeling accurate relationship between coupling baselines and two-dimensional (azimuth and range) inteferometric fringe frequency under the ellipsoid earth model, the along-track and cross-track baseline can be estimated separately by interferometric phase decoupling. By selecting several segments from interferometric phase during the whole data-take time and estimating instantaneous baseline of each segment, the dynamic baseline can be obtained via a linear filtering. Besides, to improve the baseline estimation accuracy, Semi-Newton iterative method is applied to acquire high-precision fringe frequency estimation, which can make the baseline estimation achieve centimeter level precision. The simulation validates the approach.