Direction estimation of mixed noncoherent and coherent signals with oblique projector

In this paper, we investigate the direction-of-arrivals (DOAs) estimation of a mixed noncoherent and coherent signals impinging on a uniform linear array (ULA). The DOAs of noncoherent and coherent signals are estimated separately, and a new oblique projector is obtained to isolate the coherent signals from the noncoherent ones. Compared with previous works, the proposed method overcomes the “saturation effect” encountered by most differencing and oblique projection based methods where the estimated DOAs of coherent signals have high elevated error floors. Moreover, the computationally intensive eigendecomposition is avoided and the numerical examples confirm the effectiveness of the proposed method.