Signal level determining apparatus and method

摘要

An apparatus and method is disclosed for detecting a signal in the presence of background noise which includes impulsive noise. Each value of a signal is mapped to a point on a semicircle defined by two coordinates on orthogonal axes in two-dimensional space. A respective mean is calculated of each of the two coordinates of the transformed points, and the two means are used to calculate a mean direction of the points on the semicircle. The mean direction is reverse-mapped back into the signal domain and compared against a detection threshold. The detection threshold may be set in dependence upon the concentration of the points on the semicircle. The apparatus is particularly suited to detecting a signal reflected from a small object in the presence of interfering signals backscattered by a dynamically disturbed sea surface.