An unambiguous DOA estimation method for coprime array with displaced subarrays

•The problem of directional matrix ambiguity in DOA estimation using coprime array with displaced subarrays (CADiS) is investigated.•The proposed method successfully distinguishes and detects the true DOAs without ambiguity.•The simulation results promise that the proposed method offers superior reliability and estimation accuracy compared to the existing methods. In this paper, the direction-of-arrival (DOA) estimation using a coprime array with displaced subarrays (CADiS) is researched. Mostly, subspace-based methods have been studied for DOA estimation with CADiS. However, the subspace-based methods suffer from the problem of directional matrix ambiguity. It occurs due to the non-uniform linear array configuration of CADiS, whereby there always exists a set of DOAs with linearly dependent directional vectors. As a consequence, the directional vectors that are not associated with true DOAs also lie in the signal subspace and result in an estimate of true and ambiguous DOAs. In the proposed method, the true DOAs are distinguished from ambiguous estimates using the estimated power of the transmitted signals. Here, the source covariance function is derived based on the signal subspace eigenvalues and its associated eigenvectors to estimate the power of the transmitted signals. The proposed method successfully detects the true DOAs and eliminates ambiguous estimates. The performances of the proposed method are validated through simulation studies for reliability and accuracy of the estimation.