Maximum likelihood DOA estimation for constant-modulus signal

An investigation into the direction finding problem in the case of a consta nt-modulus signal is presented. A simple expression for the maximum likelih ood estimator (MLE) is derived in the single source case. The MLE correspon ds to an L-1-type beamformer as opposed to the L-2-beamformer that results in a deterministic but not necessarily constant-modulus signal. Numerical e xamples show that the proposed estimator has a performance very close to th e Cramer-Rao Bound for a wide range of scenarios.