Interferometric Phase of Clutter-Suppression Residuals Aided Multichannel SAR-GMTI

For multichannel synthetic aperture radar (SAR) ground moving target identification (GMTI) in heterogeneous and strong clutter backgrounds, it is challenging to accurately detect slow and weak targets when relying solely on the magnitude of clutter-suppression residuals, due to the significant clutter residuals and signal-to-noise losses. To address this, a detector that leverages both the magnitude and phase information in multichannel SAR-GMTI clutter suppression is proposed. For a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i>-channel SAR system, the detection test is formulated as the product of the residual magnitude from <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i>-channel clutter suppression and a phase factor derived from the interferometric phase between two residuals from the first and last <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> - 1 channels. This phase factor captures the dissimilarity from the clutter, enabling the suppression of strong clutter residuals and improving the signal-to-clutter-plus-noise ratio (SCNR). Using the product clutter model, a constant false alarm ratio detection framework is designed. The receiver operator characteristic metrics, obtained from simulations and real-data experiments, validate the proposed method’s superiority over the state-of-the-art techniques, and the detection sensitivity on the clutter heterogeneity, correlation coefficients between pairs of clutter-suppression residuals, and target parameters is analyzed for practicality. In the X-band airborne radar GMTI experiments, the minimum discernible input SCNR of -6 dB for target radial velocity of 4 m/s and 0 dB for 2 m/s demonstrate the effectiveness in detecting the dim targets within strong clutter.