Tracking highly correlated sources via multi-stage constant modulus array

An effective method is proposed for "half blindly" recovering coherent signals impinging on a uniform linear array (ULA) and estimating their directions of arrival (DOAs). The generalized steering vector is blindly estimated from the CM array, where the steering vectors to all coherent signals are reconstructed directly by using the property of sub-array shift-invariance. When used as the array weighting, the steering vectors will provide recovered signals in corresponding beams. DOAs can be estimated from the angular spectrum subsequently. Results from the computer simulations and the real data analysis are in good agreement with theoretical analysis. Our method not only can resolve closely spaced coherent signals, but also is shown to be more robust to system errors compared to some other DOA estimation algorithms.