Abstract <p>This paper describes the methodology and results of marine experiments on the construction and analysis of direction-finding reliefs and recorded trajectories from the standpoint of classifying observed sources (surface and underwater objects) in noise direction-finding mode as applied to autumn conditions in a coastal wedge area. It is shown that, in noise direction-finding mode, trajectory bearing modulation occurring when signals propagate with reflection from boundaries, namely, the surface and bottom, can be used in addition to the known classification features for distinguishing surface and underwater objects. This modulation is efficiently detected after the power of strong signals is limited.</p>