Beam domain imaging method based on sub-array division

Abstract

The invention discloses a beam domain imaging method based on sub-array division. The method comprises the steps that step (1) the number and direction of target signal sources are estimated by usingan azimuth spectrum of a received signal of a uniform linear array; step (2) the uniform linear array is divided into a plurality of sub-arrays of the same size and overlapping one another, and the received signals of the sub-arrays are subjected to spatial filtering in a specified direction to obtain beamforming results of the sub-arrays; the beamforming results of the sub-arrays are treated as output of virtual elements, the virtual elements are combined to a virtual linear array and the output of the virtual linear array is calculated; and step (3) a high-resolution direction of arrival (DOA) estimation algorithm is used for realizing the estimation of the echo direction based on the output of the virtual linear array. The beam domain imaging method performs beamforming in the specifieddirection on the sub-arrays that is equivalent to spatial filtering of the signals, the signal intensity in the specified direction is enhanced while the interference of incoming waves in other directions is filtered out, and the signal-to-noise ratio is improved.

Description

technical field [0001] The invention belongs to the field of sonar signal processing, and in particular relates to a method for improving DOA estimation performance under the condition of multi-path signals or low signal-to-noise ratio of received signals, in particular to a beam domain imaging method based on subarray division. Background technique [0002] Internationally, since the 1970s, the depth-sounding side-scan sonar has been studied, and the signal processing methods used in the sounding are divided into three types. The first is the acoustic interference technology, which uses two parallel linear arrays. When the phase difference of the echoes received by the two linear arrays is 0 or π, the direction result can be obtained, but it has few sounding points and poor sounding accuracy. The second is the differential phase estimation technique, which uses two parallel linear arrays, can obtain hundreds of sounding points for each launch, and has the advantage of high ...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of low DOA estimation accuracy in the presence of multi-channel signals or low signal-to-noise ratio at the far end of the existing imaging method when it is applied in high-resolution sounding side-scan sonar. Problem; A beam domain imaging method based on subarray division is proposed, which can estimate the angle of arrival of multiple echoes at the same time, and maintain good detection performance in the case of low signal-to-noise ratio

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