Research On Doa Estimation Of Coherent Signal Based On Virtual Array Technology

With the rapid development of science and technology, frontier science led by information technology has been introduced into human life. Array signal processing applied very well not only in the field of military, but also in the civil side. The non-stationary class of coherent wideband signal direction of arrival (DOA) estimation is one of the major research subjects in array signal processing. At the same time, virtual array technology emerges and develops rapidly to meet the need of improving the utilization rate of resources and reducing the manufacturing cost engineering technology. Applying array technology method to DOA estimation has become a hot research field.This paper focuses on virtual array technology as well as its application in DOA estimation, and the coherent wideband LFM angle direction finding problem in FRF domain. The main work includes the following aspects:1. This paper first introduces the basic model of signal, involving the wideband signal and narrow-band signal. In the meantime, it explains a typical LFM signaling expression and analyzes its time domain and frequency domain properties. Then the paper briefly discusses FRFT and compares the time-frequency characteristic of FRFT and WVD in regard to LFM signals by simulation experiments.2. Then the paper studies MUSIC algorithm and coherent signal estimation algorithm, FBSS algorithm under the narrow-band signal model. It gives the FBSS algorithm in FRF domain. This method can be used to estimate wideband coherent LFM signal, but the accuracy is not sufficient due to the inherent characteristic of this estimation method. In regard to this problem, restructuring matrix data method was introduced, this paper illustrates summation and average of covariance matrix of rows and columns of the Toeplitz matrix by constructing data in FRF domain. Simulation results show that the improved method presents a high estimation precision, and provides better resolution to incident signals for a number of small angle differences.3. In regard to the problem of reducing the aperture of array, the paper introduces virtual array technology, and elaborates several typical methods respectively. This chapter focuses on the virtual array transformation method, also this method without reducing the aperture of array, but under low SNR and small angle difference condition, the effect is not satisfying. Corresponding to this problem, an improved forward/backward virtual array transformation method was derived, simulation results show that the improved method has good estimated performance. At last, the improved method was introduced to the wideband coherent LFM signal DOA estimation in FRF domain, so as to enrich the application fields of virtual array technology.