An approximate expression for the Cramér–Rao bound on direction-of-arrival estimation with small ring arrays
D.N. Swingler · The Journal of the Acoustical Society of America · 1993
It is demonstrated that the Cramér–Rao lower bound on direction-of-arrival estimation with two uncorrelated but closely spaced narrow-band sources impinging on a small circular array is well approximated by a modification of a recently published, extremely simple, nonmatrix, line-array formula. The approximation is demonstrated to be useful for a number of sensors from about 5 to 30, SNR’s from −30 to +30 dB, source separations down to about 0.1 beamwidths, and radius-to-wavelength ratios from 0.1 to 2. The rms error is about 30%.