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Orbit determination errors are expected to be a major threat for obtaining focused images on Geostationary Synthetic Aperture Radar (GeoSAR) missions. A ground-based interferometer system is presently being under research to determine the satellite orbit with the required precision. However, from that system, it must be addressed which orbit determination techniques offer better results for that purpose. This paper provides a comparison between two differential correction techniques: the least squares (LS) and the extended Kalman filter (EKF) techniques., Peer Reviewed, Postprint (published version)

The final publication is available at link.springer.com via http://dx.doi.org/10.1007/s11432-016-9052-y, Future GeoSAR missions are expected to provide higher resolution radar images featuring shorter revisit times by locating a radar payload on-board of a geostationary satellite. One of the main challenges in GeoSAR processing is accurately determining the satellite orbit to obtain a precise phase history, in order to properly focus the retrieved data. To tackle this challenge, a multiple baseline ground-based interferometer is proposed as a compact and reliable method to achieve an unprecedented accuracy. As a proof of concept, this paper presents the results obtained from a single baseline prototype, whose results can be extrapolated to a larger system, able to be used in future missions., Peer Reviewed, Postprint (author's final draft)

This paper proposes a method to solve the absolute phase ambiguity introduced by an orbit determination interferometer system, suitable for GeoSAR missions. This method will be complemented with simulated results in order to validate its reliability., Peer Reviewed, Postprint (published version)

The paper analyzes the problem of achieving a coherent operation in Geostationary SAR (GEOSAR) missions intended for continuous monitoring of land surfaces. In contrast to LEOSAR missions, GEOSAR uses very long SAR integration times (from minutes to hours). Accordingly phase errors due to orbit perturbations, radar master oscillator drift, atmosphere propagation and other sources must be conveniently compensated during SAR processing to avoid image defocusing. A network of Active Radar Calibrators (ARC) distributed on the observed scene is proposed, providing echo envelope and phase observations before Synthetic Aperture Processing. In this way the radar antenna phase center trajectory and other phase error sources can be continuously tracked and compensated using a pyramidal sub-aperture processing approach., Peer Reviewed, Postprint (published version)

This paper proposes two different calibration techniques for Geostationary Synthetic Aperture Radar (GEOSAR) missions requiring a high precision positioning, based on Active Radar Calibrators and Ground Based Interferometry. The research is enclosed in the preparation studies of a future GEOSAR mission providing continuous monitoring at continental scale., Peer Reviewed, Postprint (author's final draft)