Directions-of-arrival estimations of multiple coherent broadband signals

In the problems of estimating the directions-of-arrival (DOAs) of multiple coherent broadband signals, the coherent signal-subspace (CSS) method (H. Wang and M. Kaveh, 1990) and the coherent interpolation (CI) method (M. Wax et al., 1985) have been proposed. The performances of the two methods and that of total least squares estimation (LSE) of signal parameters via rotational invariance techniques (TLS-ESPRIT) (Y.H. Chen and F.P. Yu, 1991) which is a high-resolution narrowband signal-subspace approach to an array system with a translation invariant structure, are compared. In the case of unequal-signal powers, the CSS method is not as good as the CI method. Since CI has the disadvantage of larger estimation errors for larger arrival angles, a new spatial phase-shifting technique to improve its performance is presented. Simulation results show the effectiveness of the proposed method