Underwater acoustic target radiation noise modulation spectrum reconstruction method based on group sparse structure

Abstract

The invention discloses an underwater acoustic target radiation noise modulation spectrum reconstruction method based on the group sparse structure. The method comprises the following steps that step1, a continuous spectral component R<c> (t) and a linear spectral component R<l> (t) of underwater acoustic target radiation noise are simulated to form underwater acoustic target radiation noise R (t); step 2, the R (t) is subjected to amplitude modulation to obtain a modulating signal x (t); step 3, the x (t) is subjected to normalization, and a band-pass filter is used for obtaining noise modulation signals y<l> (t) of L frequency bands; step 4, amplitude modulation data of the y<l> (t) on each sub-band are estimated, wherein the formula (please see the specification for the formula); step5, a formula (please see the specification for the formula) are subjected to discrete sampling and are represented by a sparse frequency coefficient, wherein the formula (please see the specificationfor the formula), and through designing of prior distribution of a formula (please see the specification for the formula), a high resolution modulation spectrum generation model based on the group sparse structure is constructed; step 6, posteriori distribution of a formula (please see the specification for the formula) is derived based on the expectation maximization method; and step 7, a parameter estimation formula is used for an iterative solution of a formula (please see the specification for the formula) to estimate a high resolution sparse modulation spectrum. Correlation of modulationspectrum positions of sub-bands of underwater acoustic target radiation noise is used for achieving high resolution reconstruction of the underwater acoustic target radiation noise modulation spectrum.

Description

technical field [0001] The invention belongs to the field of sonar signal processing, and in particular relates to a method for reconstructing modulation spectrum of underwater acoustic target radiation noise based on group sparse structure. Background technique [0002] Ship radiated noise is a good underwater sound source. The mechanical vibration noise and propeller noise of underwater targets are the main noise sources of underwater acoustic targets such as surface ships, submarines, and torpedoes. Propeller cavitation noise will produce amplitude modulation with a distinct sense of rhythm. The spectral lines that appear as linear features are called "line spectra". The position of the modulation line spectrum on the spectrogram is relatively stable, and it can reflect some target characteristics such as the propeller speed and the number of blades. Discovery, separation. This feature makes it one of the important factors in object detection and recognition. Therefor...

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Problems solved by technology

However, the resolution of the signal line spectrum obtained by the FFT method is affected by the window length, which may prevent the more important spectral lines from being detected, resulting in the omission of important frequency domain information of the signal in the underwater acoustic measurement. On the other hand, the traditional multi-based Sub-band frequency division technology modulation spectrum analysis method Each sub-band processing is independent of each other, and the correlation between sub-band modulation spectra between sub-bands is not used. Therefore, it is necessary to find a new solution for modulation spectrum analysis to obtain high-precision modulation spectra.

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