On Ground Demonstrator Of Digital Stabilization For High-Resolution Earth Observation Time Of Delay Integration Imaging

CNES (French Space Agency) has developed a dedicated test bench to demonstrate its solution of digital stabilization for relaxing the AOCS constraints for high-resolution Earth observation Time of Delay Integration (TDI) imaging, based on a CNES patent(1). TDI sensors are sensitive to high frequency attitude disturbances which may induce blurring effects when increasing TDI stages number and thus exposure time. A solution to relax the microvibration constraints (or no longer constrain the number of lines to be accumulated) is to compute, in real-time, the shift between each line and coregister them before summation. CNES solution includes a motion sensor dedicated to shift measurements, a fast real-time algorithm to compute the shift between two consecutives images delivered by the motion sensor, a multi-frame TDI sensor, and an algorithm to resample images delivered by sub-TDI devices using computed shifts, before summing them up in order to obtain the final image. The optimization study of the motion sensor and the performances of the gradient-based algorithm on these images have been already presented in a previous paper2. In this paper, we describe the dedicated test bench which contains each part of the presented chain and the obtained performances.