The geosynchronous circular synthetic aperture radar (GEOCSAR) is an innovative SAR system

which can produce high resolution three-dimensional (3D) images and has the potential to provide 3D deformation measurement. With an orbit altitude of approximately 36 000 km

the orbit motion and orbit disturbance effects of GEOCSAR behave differently from those of the conventional spaceborne SAR. In this paper

we analyze the effects of orbit errors on GEOCSAR imaging and interferometric processing. First

we present the GEOCSAR imaging geometry and the orbit errors model based on perturbation analysis. Then

we give the GEOCSAR signal formulation based on imaging geometry

and analyze the effect of the orbit error on the output focused signal. By interferometric processing on the 3D reconstructed images

the relationship between satellite orbit errors and the interferometric phase is deduced. Simulations demonstrate the effects of orbit errors on the GEOCSAR images

interferograms

and the deformations. The conclusions are that the required relative accuracy of orbit estimation should be at centimeter level for GEOCSAR imaging at L-band

and that millimeter-scale accuracy is needed for GEOCSAR interferometric processing.