DOA Estimation for Incoherent Wideband Signals with Low Signal-to-noise Ratio

The test of orthogonality of projected subspaces (TOPS) is a classical incoherent wideband direction of arrival algorithm. However, TOPS and its improved algorithms have limitations in low signal-to-noise ratio (SNR) scenarios, such as poor resolution and the emergence of pseudo-peaks. To overcome these limitations, an improved algorithm is proposed in this paper. The noise subspace is estimated via the covariance matrix to avoid a priori knowledge about the number of sources. Also, a modified matrix using the orthogonality between the array manifold and the noise subspace is constructed and the spatial spectrum of signals using the Frobenius norm of the matrix is determined. Simulation results indicate that the proposed algorithm could effectively enhance the estimation accuracy and resolution even at low SNR while avoiding pseudo-peaks at any SNR.