Abstract:

When multiple sources coexist during a rotating period, the emitting signals from these sources are interleaved and hence implicitly related, since only frequency, magnitude and phase difference can be obtained in each sample. In order to realize the joint estimation of multiple parameters simultaneously and efficiently, this paper proposes a new scheme to estimate the parameters of multiple time-varying signals using maximum expectation algorithm. A high-dimensional multi-parameter optimization problem is decomposed into several parallel low-dimensional problems for solving. The method mainly consists of two steps: solving expected value and maximizing expected value. The expected value step mainly establishes the correspondence between the received signal and the radiation source, that is, signal sorting, while the expected value maximization step uses the maximum likelihood method to estimate the incident Angle information of the radiation source. The two steps are iterated each other, and the separation and direction finding of the radiation source signal are carried out alternately. In this paper, the closed form solution of the maximum likelihood method for the passive synthetic circular array phase difference data is derived for the exact estimation of the incident Angle, and the phase fuzzy solution is calculated by the complex response of the received signal, and the theoretical lower limit of the direction finding accuracy is also derived. Finally, the effectiveness of the proposed method is verified by numerical simulation.

Key words: direction of arrival (DOA) estimation, passive synthetic array, maximum likelihood (ML) estimation, expectation maximization (EM) algorithm