Abstract: For the problem of the source number and DOA estimation of the weak signals in the interference of the strong signals, a novel method based on synthetic spectrum is proposed. In this method, the outputs of the eigen-beam channels are superimposed by different weights to form a spatial spectrum function. Then the function is used to weight the spatial spectrum function derived from the noise subspace approximation method. Finally, the synthetic spectrum function is constructed to estimate the DOAs of the weak signals without the prior knowledge of source number. Compared to the prevois method based on eigen beamforming, the proposed method has better performance when the DOAs of weak signals are close to each other. The effectiveness and advantage of this method is verified by the simulation results.

Key words: weak signal DOA estimation, strong signal suppression, unknown source number, noise subspace approximation, synthetic spectrum