Range-Ambiguous Clutter Suppression by Phase-Coding and Subspace Projection

The low-altitude surveillance radar often operates in Pulse Doppler (PD) mode. The high PRF pulse train waveform of this mode can cause range ambiguity of targets and clutter, posing significant challenges for target detection and clutter suppression. This paper presents a range-ambiguous clutter suppression technique for PD radars operating in severe range-ambiguous clutter environments. The proposed method employs random phase coding modulation on the pulse train to achieve range de-ambiguation, while implementing subspace projection filter (SPF) to suppress clutter across different folded range segments. Experimental verification conducted on a low-altitude surveillance radar deployed in strong clutter environments demonstrates that this approach not only effectively resolves range ambiguities through random phase coding, but also achieves efficient suppression of clutter across various folded range segments.