Narrowband line-array beamforming: practically achievable resolution limit of unbiased estimators
D.N. Swingler · IEEE Journal of Oceanic Engineering · 1994
Based on an approximation to the Cramer-Rao lower bound, it is demonstrated that meaningful resolution with an unbiased narrowband estimator requires a source separation of at least about 1/10 of a Rayleigh beamwidth, even under ideal circumstances, with 1/4 beamwidth being a more practically achievable figure.>