A Motion Compensation Strategy for Airborne Repeat-Pass SAR Data

Abstract

Abstract-Generating accurate repeat-pass interferometric airborne SAR products demands the precise compensation of the 3-D motion of the aircraft. This requires to estimate and correct small residual motion errors within the accuracy limits of the sensor navigation sub-system, e.g. using residual motion compensation algorithms. Because of their data-driven nature, the performance of these algorithms severely degrades for heavily decorrelated interferograms. This letter proposes a generic residual motion error (RME) estimation and compensation strategy optimally estimating RME in a stack of SAR acquisitions, where some interferometric pairs are strongly affected by decorrelation. The algorithm works even if the whole scene decorrelates, as long as the coherence magnitude is reasonably high over short temporal and spatial baselines. The approach entails correcting the navigation data of each slave image of a one-to-many interferometric network with a cumulative correction. The summation is over the results of a precursory application of a general data-driven residual motion compensation algorithm (e.g. multisquint) to interferometric pairs for which the impact of interferometric decorrelation is marginal (i.e. small temporal and/or spatial baselines). Compared to other RME correction strategies, the main appeal of the proposed approach lies in the simplicity of its implementation. The overall methodology is tested on a zero-baseline time series acquired at L-band by the DLR's airborne system F-SAR.

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