Source enumeration method by combining diagonal loading andconstructing second-order statistics

A source enumeration method based on diagonal loading of eigenvalues and constructing second-order statistics isproposed, for the case that the antenna array observed signals are overlapped with spatial colored noise, and thenumber of antennas compared with the number of snapshots meet the requirement of general asymptotic regime.Firstly, the sample covariance matrix of the observed signals is obtained, the eigenvalues of the sample covariancematrix can be acquired by eigenvalue decomposition, and the eigenvalues are diagonally loaded, and a new formulafor calculating the diagonal loading is presented. Based on the diagonal loaded eigenvalues, the difference valuesare calculated for the adjacent eigenvalues after diagonal loading, and the statistical variance of the differencevalues is calculated. On this basis, the second-order statistics of the difference values are constructed, and whenthe second-order statistics are minimized, the corresponding number of sources is estimated. The proposed methodhas wide applicability, which is suitable for both general asymptotic regime and classical asymptotic system, and issuitable for both white Gaussian noise environment and colored noise environment. The method makes up for thelack of source enumeration methods in the case of general asymptotic system and colored noise.