Options for high-precision motion compensation for airborne differential SAR interferometry

Differential interferometry using space-borne SAR sensors has become an established technique for detecting and monitoring centimetre-scale deformations of the Earth´s surface, as well as glacier flows and land slides. Although often very efficient, the use of space-borne SAR data has several drawbacks, namely phase artifacts caused by atmospheric effects and very low coherence due to long data acquisition intervals. Airborne sensors on the other hand may overcome most of the problems mentioned above and provide a much higher flexibility in sense of spatial resolution, used wavelength and data acquisition. However, the use of airborne sensors has been prevented by insufficiently accurate motion compensation of the sensor platform. In this paper, the performance and deficiencies of the different approaches for estimation of residual motion errors are compared and evaluated, in the face of their application in airborne differential SAR interferometry. Some preliminary results of airborne differential SAR interferometry, obtained using an optimised motion compensation scheme, will also be shown. The analysis carried out in this paper is based on repeat-pass interferometric data acquired by DLR´s experimental SAR system (E-SAR) in L-band.