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Automatic detection and extraction method for low and medium frequency line spectrums of ship radiation noise

A radiation noise and automatic detection technology, which is applied to pattern recognition in signals, character and pattern recognition, instruments, etc., can solve problems such as the inability to automatically detect and extract low-frequency line spectrum features, missing detection of weak low-frequency line spectrum, etc., and achieve improvement The effect of automatic extraction ability, improving the level of intelligence, and optimizing the effect

Active Publication Date: 2019-08-16
THE PLA NAVY SUBMARINE INST
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  • Summary
  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

Using the existing fixed-threshold line-spectrum feature extraction method, using the noise amplitude in the entire low-frequency range as the reference threshold for line-spectrum detection will result in the missing detection of weak low-frequency line spectra; The extraction method needs to adjust the threshold according to the actual target signal under manual participation, and cannot automatically detect and extract the low-frequency line spectrum features of ship radiation noise

Method used

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  • Automatic detection and extraction method for low and medium frequency line spectrums of ship radiation noise
  • Automatic detection and extraction method for low and medium frequency line spectrums of ship radiation noise
  • Automatic detection and extraction method for low and medium frequency line spectrums of ship radiation noise

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Effect test

Embodiment 1

[0032] Use the method that the present invention provides to extract the radiation noise low-frequency line spectrum of ship A, the flow chart is as follows figure 1 shown. figure 2 It is a screenshot of the low-frequency history map of the radiation noise of ship A displayed on a certain device. The abscissa of the screenshot is "frequency (Hz)", and the ordinate is "time (s)".

[0033] It can be observed from the screenshots that there are weak target line spectrum components near 275Hz and 551Hz, but due to the high energy of the high-frequency band of ship radiation noise, the low-frequency line spectra of the two targets at 275Hz and 551Hz are very weak in comparison. Possesses clearly identifiable characteristics.

[0034] If the traditional Fourier transform method is used to calculate the spectrum of the radiated noise signal of ship A, the two target low-frequency line spectra at 275 Hz and 551 Hz are submerged in the noise interference.

Embodiment approach

[0036] Step 1: Use the acquisition card to collect the radiated noise of the target ship A, and the sampling frequency is 5kHz. .

[0037] Step 2: Select the ship A radiation noise signal with a time length of T=30s, and divide it into N=30 frames according to the time length of each frame t=1s. Using the existing Fourier transform method to calculate the frequency spectrum of each frame of ship radiation noise signal, and obtain the frequency spectrum of one frame of ship A radiation noise— image 3 ; After completing the spectrum calculation of all 30 frames, add and accumulate the spectrum of 30 frames to obtain the accumulated spectrum map of 30 frames of radiation noise of ship A ( Figure 4 ).

[0038] To further illustrate the principle, the Figure 4 The weak line spectrum of 200-600Hz is locally enlarged to obtain Figure 5 ; It can be seen from the comparison that Figure 4 There are only weak line spectrum features at 275Hz and 551Hz, which are far smaller than...

Embodiment 2

[0045] Figure 10 The multi-time accumulation spectrum diagram of the radiated noise of ship B is given. The low-frequency line spectrum of ship B is relatively clear, and both the existing method and the method of the present invention can be used to extract the line spectrum features, but the line spectrum results of the method of the present invention have fewer interference line spectra and the features are more pure.

[0046] Step 1: Use the acquisition card to collect the radiation noise of the target ship B, and the sampling frequency is 5kHz.

[0047] Step 2: Also select the radiation noise signal of ship B with a time length of T=30s, and divide it into N=30 frames according to the time length of each frame t=1s. Then the spectrum of 30 frames is added and accumulated to obtain the accumulated spectrum of ship radiation noise.

[0048] Figure 10 is the accumulated spectrogram of 30 frames of ship B radiation noise. As can be seen, Figure 10 There are obvious li...

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Abstract

The invention discloses an automatic detection and extraction method for low and medium frequency line spectrums in ship radiation noise. The method comprises: acquiring signals; accumulating frequency spectrums at multiple moments; smoothing the accumulated frequency spectrum; carrying out smoothing item removal on the logarithm decibel spectrum; extracting line spectrum; if the line spectrum ishigher than the line spectrum threshold H, reserving the line spectrum, otherwise, removing the line spectrum; and carrying out traversal comparison on amplitudes of all frequency points of the frequency spectrum to obtain a final line spectrum extraction result. According to the method, the line spectrum characteristics of the target ship can be automatically detected and extracted by collectingand analyzing the radiation noise of the ship. The method is suitable for weak line spectrum detection under the condition of low signal-to-noise ratio and non-low signal-to-noise ratio, has obvious advantages compared with an existing line spectrum detection method, effectively improves the target feature automatic extraction capability, optimizes the underwater sound target recognition effect, and improves the intelligent level of underwater sound equipment.

Description

technical field [0001] The invention belongs to the technical field of underwater acoustic target recognition, and relates to an automatic detection and extraction method of low-frequency line spectrum in ship radiation noise. Background technique [0002] The problem of ship noise target recognition has always been an internationally recognized major technical problem. One of the key technologies of ship noise identification is to extract the line spectrum features of target radiation noise. With the development of ship noise reduction technology, the noise level of the radiated noise of new surface ships and submarines has been decreasing year by year, and the target recognition work is facing new changes: First, the importance of low-frequency line spectrum features is increasing. Compared with low-frequency band signals, the propagation attenuation of high-frequency band signals in ship radiation noise is large and the propagation distance is short. The medium-high freq...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06K9/00
CPCG06F2218/04G06F2218/08
Inventor 李海涛程玉胜邱家兴程健车永刚丁超
Owner THE PLA NAVY SUBMARINE INST
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