To mitigate the masking of weak target echoes by cumulative reverberation in continuous active sonar (CAS), and to achieve real-time reverberation suppression under the constraints of short detection windows, this paper proposes a sequential sub-band sparse filtering with QR decomposition (QR) updates method based on low-rank and sparse decomposition. By leveraging the inherent sequential nature of CAS sub-band outputs, a low-rank background model is constructed via incremental QR updates. This framework allows for the rapid extraction of sparse components from each sub-band, effectively separating steady-state reverberation, reverberation fluctuations, and target echoes. Validation using shallow-water experimental data demonstrates that the proposed method achieves rapid convergence with only a few sub-band inputs. It significantly reduces interference from reverberation fluctuations, maintains the structural continuity of targets under low signal-to-noise ratio conditions, and improves the detectability of weak echoes. The online separation framework ensures superior computational efficiency while enhancing system adaptability to complex reverberant environments.
LIU et al. (Sun,) studied this question.