Array sparse method for broadband non-frequency-variable multi-beam imaging sonar

Abstract

The invention discloses an array sparse method for a broadband non-frequency-variable multi-beam imaging sonar. With the Bessel function, fitting of influences on array guiding vectors by different frequency points in the broadband signal bandwidth is performed and a broadband signal multi-beam forming model under the far-field situation is established; on the premise that the formed multiple beams approximate a reference beam, a minimum number of effective array elements are searched and multiple sets of weighting coefficients are calculated; a highly nonlinear sparse array optimization problem is transformed into a sparse signal reconstruction problem in the compressed sensing theory, a reconstruction weighting coefficient is calculated iteratively by an underdetermined system localizedsolution algorithm, and a sparse array structure is determined; a convex optimization theory is introduced so as to form a plurality of low-side-lobe beams and a multi-beam array sparse side-lobe suppression model for array element excitation is established. According to the invention, the main lobes of a plurality of formed beams are not extended with changes of signal operating frequencies; andpeak side-lobe levels of multiple beams formed by the sparse array are reduced effectively.

Description

technical field [0001] The invention belongs to the field of sonar signal processing, in particular to an array sparse method for multi-beam imaging sonar. Background technique [0002] Underwater acoustic imaging generally uses an array composed of multiple array elements for echo reception and beam weighting processing to form a beam pattern with high gain and low sidelobe. In order to avoid the impact of excessive grating lobes on beam performance, when array elements are arranged in a multi-element system, the interval between adjacent array elements is generally required to comply with the half-wavelength array principle. Similarly, in sonar equipment, in order to obtain high resolution, large-scale acoustic arrays are used to process acoustic signals, which is often accompanied by problems such as high power consumption, complex subsequent processing circuits, and high system hardware costs. Array sparse design technology is one of the effective ways to solve the abov...

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Problems solved by technology

[0007] In order to solve the technical problems raised by the above-mentioned background technology, the present invention proposes an array sparse method for multi-beam imaging sonar, considering the operating frequency band of broadband signals, at the cost of the minimum number of array element structures, constructing multiple arrays approaching the desired beam Scan the beam to ensure that the main lobe of the formed multiple beams does not widen with the change of the signal operating frequency, and at the same time avoid the problem that the main target detected by the sonar cannot be distinguished from the cluttered background image due to the rise of the side lobes of the beam

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