Self-calibrated Method for Distributed small satellite SAR Systems

In practice, the performance of the Distributed small satellite synthetic aperture radar (DSS-SAR) systems is affected seriously by the unavoidable array errors. In this paper, the phase and position errors are considered with the gain error calibrated by the adaptive processing. The clutter echo usually has Doppler (azimuth) ambiguities which is caused by lower pulse repetition frequency (PRF) in such systems. The array error estimation method is given based on the Doppler ambiguities. By analyzing the conventional method in which the phase error and the position error are estimated by iterating between each other, we find that: the steering vector of one Doppler ambiguity associated with the zero Doppler bin is conjugate to its opposite one. So the phase error can be directly obtained though the position error exists. The proposed method is given based on this. It estimates and the position error independently without iterations between them. The proposed method can performs approximately as well as the conventional method but with less computation load. Simulations can verify its effectiveness.