A new iterative coherent subspace method for wideband direction finding

In this paper, a new wideband direction-of-arrival (DOA) estimation algorithm, which is an iterative coherent subspace method based on two-dimensional discrete Fourier transform (2D-DFT), is proposed. Two stages of focusing are accomplished in the algorithm. Firstly, a modified 2D-DFT, which has accomplished a preliminary focusing process, is exploited on the received data to achieve initial estimates that are more accurate than the results of beamforming methods. More importantly, in the first stage, the real array manifold is projected to a new virtual array manifold that is more suitable for subsequent focusing. Secondly, based on the transformed data, an iterative process in which each step works on the estimates available from previous iterations is applied to the transformed data to estimate the DOA. Because of the implementation of 2D-DFT, the proposed algorithm can achieve a higher resolution and a better convergence performance than conventional methods, especially when the incoming sources have irregular distributions in the frequency domain. Performance analysis and simulation results show that the proposed algorithm works properly and effectively.