Bispectrum Analysis Method Based on Combination of Cyclic Modulation Spectrum and Segmented Cross-correlation

Abstract

The invention relates to a bi-spectrum analysis method based on combination of a circulation modulation frequency spectrum and segmentation mutual correlation. The method comprises steps of calculating a circulation modulation frequency spectrum of a signal to noise ratio hydrophone signal; carrying out Fourier transform on the circulation modulation frequency spectrum to obtain a time domain signal; inputting the time domain signal into a full-phase position digital filter; dividing a filtered signal into multiple segments of mutually correlated bi-spectrums and then carrying out combination;calculating the significance level of the bi-spectrum; taking the significance level as an acceptance region of secondary phase position coupling; calculating to obtain a slice spectrum of a bi-coherent index spectrum; and finally, extracting an axis frequency and harmonic waves of each order of a target subjected to the secondary phase position coupling from the low-frequency band of the slicingspectrum. According to the invention, under the condition of a low signal to noise ratio, the axis frequency and harmonic waves subjected to the secondary phase position coupling in the hydrophone signal can be effectively detected; the method has quite high sensitivity and robustness; and data verification shows that even under the condition of the low signal to noise ratio, the axis frequency and harmonic waves of each order of the target subjected to the secondary phase position coupling can be precisely detected.

Description

technical field [0001] The invention belongs to the fields of underwater acoustic engineering, marine engineering and sonar technology, and relates to a bispectral analysis method based on the combination of cyclic modulation spectrum and segmental cross-correlation, which is an improved bispectral analysis method and extracts low signal-to-noise ratio The line spectrum frequency and phase coupling information contained in the radiated noise of the target under the condition is suitable for the low signal-to-noise ratio signal of the underwater target. Background technique [0002] When using hydrophones to detect underwater targets, they often face the problem of low signal-to-noise ratio of received signals and the inability to effectively identify target information, especially when the hydrophone signal can only be relied on to determine whether the target exists. At this time, using various time-frequency analysis methods to detect whether the signal contains periodic l...

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Problems solved by technology

[0005] In order to avoid the deficiencies of the prior art, the present invention proposes a bispectrum analysis method based on the combination of cyclic modulation spectrum and segmental cross-correlation, which overcomes the defects of the existing noise envelope modulation spectrum detection method and detects the line spectrum Secondary phase coupling characteristics, correcting the frequency offset error generated by the spectrum signal, and effectively improving the robustness of the detection method

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