A severely range ambiguous clutter suppression method based on multi-domain cascaded signal processing for space-based early warning radar

The non-stationary clutter phenomenon and the severe range ambiguity make space-based early warning radar as an intricate model of received ground and sea clutter. The received clutter is severely broadened in Doppler dimension, and the degrees of freedom (DOFs) of the received clutter is severely increased. Because the DOFs of the system is always lower than the theoretical DOFs of the received clutter, the adaptive processing capability of the system is insufficient and the performance of clutter suppression is seriously degraded. A multi-domain cascaded adaptive processing method is proposed in this study. The proposed method takes full advantage of the digital antenna array to suppress a portion of the clutter energy by introducing the transmit pulse coding domain, and the remaining influential clutter energy is suppressed by introducing the elevation-dimensional receive channel domain. Finally, the clutter after the two-dimensional (2D) pre-processed is suppressed by the 2D adaptive processing in the azimuthal receive beam-receive Doppler domain. This method pre-processes the clutter data by extending the processing dimension to meet the freedom requirements of the adaptive signal processing, and the capability of clutter suppression is significantly improved. Simulation examples show the effectiveness of the proposed method.