A propeller shaft frequency searching method based on improved noise envelope signal recognition

A technology for propeller shaft and signal recognition, applied in character and pattern recognition, instruments, computer parts, etc., can solve problems such as slow iteration convergence, excessive calculation, and poor estimation accuracy

Active Publication Date: 2018-11-30
NORTHWESTERN POLYTECHNICAL UNIV
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Problems solved by technology

[0004] In order to avoid the deficiencies of the prior art, the present invention proposes a propeller shaft frequency search method based on improved noise envelope signal identification, which overcomes the la

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  • A propeller shaft frequency searching method based on improved noise envelope signal recognition
  • A propeller shaft frequency searching method based on improved noise envelope signal recognition
  • A propeller shaft frequency searching method based on improved noise envelope signal recognition

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Embodiment Construction

[0051] Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

[0052] A propeller shaft frequency search method based on an improved cyclic modulation spectrum method, characterized in that: firstly, the envelope is solved for the classic envelope modulation spectrum by combining wavelet packet transform and Hilbert-Huang transform steps to improve. After the first spectrum calculation of the cyclic modulation spectrum, the step of multi-target classification algorithm is added to reduce the calculation amount of the second modulation spectrum and improve the accuracy of shaft frequency detection. Specifically, the multi-scale wavelet packet decomposition is performed on the original signal first, and then the Hilbert-Huang transform is performed on each wavelet packet signal to obtain the envelope, and then all the wavelet envelope signals are reconstructed to obtain an improved noise envelope signal; after that, the solut...

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Abstract

The invention relates to a propeller shaft frequency searching method based on improved noise envelope signal recognition. The method includes: enveloping an original hydrophone signal, and performingHilbert-Yellow transform on each wavelet packet signal to obtain a wavelet envelope signal; performing wavelet reconstruction to obtain an improved noise envelope signal; calculating a time correlation spectrum, take a line spectrum protruding at the peak of the low frequency band as the suspected shaft frequency; setting a step size smaller than the frequency resolution according to the demand;forming a suspected shaft frequency set with the suspected shaft frequency as the center; performing cyclic correlation calculation on a time correlation spectral signal on each suspected shaft frequency to obtain the frequency statistical amount of a cyclic modulation spectrum; and finally searching the shaft frequency of a target according to the frequency statistical amount. The method of the invention corrects axial frequency offset errors generated by the conventional cyclic modulation spectrum methods in the spectrum calculation process, improves the accuracy of the shaft frequency detection, greatly reduces the calculation amount of the loop iteration, and is convenient to implement in engineering application.

Description

technical field [0001] The invention belongs to the fields of underwater acoustic engineering, marine engineering and sonar technology, and relates to a propeller shaft frequency search method based on improved noise envelope signal identification, which is an improved noise envelope based on the combination of cyclic modulation spectrum and multiple signal classification algorithms The signal recognition method is used to extract the shaft frequency of the ship propeller and the harmonic line spectrum of each order. This method is suitable for target recognition of ship radiation noise. Background technique [0002] Theoretical research and actual measurement show that the propeller noise of a real ship is a non-stationary broadband continuous signal, and its spectrum signal is composed of continuous spectrum noise and low-frequency discrete noise. The main sound source of the continuous spectrum is the cavitation noise of the propeller. The low-frequency discrete noise is ...

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Application Information

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IPC IPC(8): G06K9/00
CPCG06F2218/06G06F2218/12G06F2218/08
Inventor 杨坤德周星月
Owner NORTHWESTERN POLYTECHNICAL UNIV
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