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 an M-channel SAR system, the detection test is formulated as the product of the residual magnitude from M-channel clutter suppression and a phase factor derived from the interferometric phase between two residuals from the first and last $M-1$ 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 (CFAR) detection framework is designed. The receiver operator characteristic (ROC) 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 are analyzed for practicality. In the X-band airborne radar GMTI experiments, the minimum discernible input SCNR of −6 dB for a 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.