Elimination of across-track phase components in airborne along-track interferometry data to improve object velocity measurements

The phase differences in airborne along-track interferometry can be used to calculate radial velocities of moving objects. This paper deals with the problem to preprocess phase and intensity data of along-track interferometry with the aim to determine velocities of slow moving objects. The phase information is often severely disturbed by quite different reasons. Beside the problem of noise sensitivity of interferometric measurements in airborne measurements additionally an unwanted across-track component could lead to systematic phase errors. We propose a first order correction of the along-track phase values by subtracting a plane which is fitted into phase values. In case of a flat scene this correction complies a 'flat Earth' correction of the phase. The described process was applied to a scene with slow moving cargo ships.