Direction-of-arrival estimation of coherent narrowband signals with arbitrary linear array

In this paper, we consider the direction-of-arrivals (DOAs) estimation of coherent narrowband signals impinging on an arbitrary linear array in a computational efficient way. A new interpolation transform based modified Capon beam-forming method is proposed without eigendecomposition, where the arbitrary linear array is transformed to a virtual uniform linear array (ULA) by utilizing the interpolation technique, and then the coherency of incident signals can be decorrelated by employing the spatial smoothing preprocessing. Further by increasing the power of array covariance matrix, a modified Capon beamformer is used to estimate the DOAs, where the component corresponding to the signal subspace is suppressed. The effectiveness of the proposed method is verified through numerical examples, and the simulation results show that the proposed method performs as well as the subspace-based method at low signal to noise ratio (SNR) or with small number of snapshots.