An apparatus configured to receive an input dataset, x, indicative of radar signals reflected from targets as received at a plurality of antenna elements; define a matrix, A, formed of direction-of-arrival-angle vectors, an, each direction-of-arrival-angle vector representing an expected response at the plurality of antenna elements of radar signals from one of the targets; define a signal amplitude vector s to represent expected complex amplitudes as received in the radar signals; define an objective function based on x, A and s; search for a set of direction of arrival angles for each of the plurality of targets by the repeated evaluation of the objective function for a plurality of candidate matrices based on matrix A; and wherein said search space comprises a plurality of discrete points, z, associated with the direction of arrival angles by a function of sin(θk).