Sea clutters with Doppler-varying spectrum exert a
notable negative impact on the detection performance, especially
with low-velocity targets, when a passive bistatic radar is employed
to detect sea-surface targets. One feasible solution is to
modulate the reference signal onto the Doppler dimension and, as
such, a filter with a wide notch and sharp edges can be obtained
to suppress the residual clutters. However, to achieve this goal, a
considerably high computational complexity is demanded in the
existing two-dimensional (2D) adaptive filters. In this context, a
novel 2D partial-update normalized least mean square algorithm
is proposed to reduce the computational load, as well as to yield
a superior clutter suppression performance. The effectiveness of
the proposed approach is verified by real-data experiments.