Sparse iterative covariance-based estimation, an iterative direction-of-arrival approach based on covariance fitting criterion, can simultaneously estimate the angle and power of incident signal. However, the signal power estimated by sparse iterative covariance-based estimation approach is inaccurate, and the estimation performance is limited to direction grid. To solve the problem above, an algorithm combing the sparse iterative covariance-based estimation approach and maximum likelihood estimation is proposed. The signal power estimated by sparse iterative covariance-based estimation approach is corrected by a new iterative process based on the asymptotically minimum variance criterion. In addition, a refinement procedure is derived by minimizing a maximum likelihood function to overcome the estimation accuracy limitation imposed by direction grid. Simulation results verify the effectiveness of the proposed algorithm. Compared with sparse iterative covariance-based estimation approach, the proposed algorithm can achieve more accurate signal power and improved estimation performance.Sensors 2020, 20, 119 2 of 12 techniques (ESPRIT) [13], where parameters are estimated by studying the subspace of the data covariance. They can provide higher resolution than nonparametric methods, but adimit two shortcomings: (1) they require the knowledge of the number of source, and (2) work well only when the sources are independent. Recently, these two kinds of approaches have been combined, leading to the so-called semiparametric approache. The recently developed iterative adaptive algorithm (IAA) [14] largely eliminates the leakage problem of the beamformer and is robust to coherent sources. However, the IAA algorithm still has resolution limitations, especially at low SNR situations. Stoica et al. have recently proposed a user parameter-free sparse iterative covariance-based estimation (SPICE) approach in [15,16], based on minimizing a covariance fitting criterion. SPICE is able to provide excellent resolution and low sidelobe levels while maintaining robustness to coherent sources. Moreover, the power of the signal can be estimated simultaneously. However, as with most power-based sparse methods, the estimation accuracy of the SPICE algorithm is limited to the direction grid. In addition, the signal power estimated by SPICE is inaccurate, especially in the case of coherent signal. In [17], a method named likelihood-based estimation of sparse parameters (LIKES) is proposed, where the same covariance fitting criterion is adopted as SPICE algorithm. The difference is that the weights in LIKES are adaptive rather than constant in SPICE. Compared with the SPICE algorithm, LIKES can obtain more accurate DOA estimation, but at the expense of computational cost. The DOA estimation accuracy will be limited to direction grid because the spatial domain is also discretized in LIKES algorithm. In [18], an iterative algorithm based on the combination of Capon and SPICE (C-SPICE) is proposed, and a mobile average initialization technolog...