DOA estimation for broadband signal that use FFT interpolation method

A method for broadband DOA estimation is proposed in this paper. By using FFT interpolation technique, virtual arrays outputs of each frequency bin of broadband signal can be obtained from physical array outputs, and these virtual arrays have the same array manifold, so DOA´s can be estimated from the outputs of virtual arrays. Ordinarily, preliminary source locations, which are used to construct focussing matrices, should be estimated prior to forming covariance matrices, whereas, the method which needs information of source locations suffers from an asymptotic bias, and the bias increases with the deviation of preliminary source location from the true DOA´s. The method proposed in this paper, by preprocessing the array outputs, the common covariance matrices can be formed, and DOA´s can be estimated by using conventional method. Results of DOA estimation are unbiased because this method needn´t preliminary information of source locations. Simulation results are provided to illustrate the effectiveness of proposed method.