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Robust ship noise identifying method

An identification method and technology for ships, which are applied in the measurement of ultrasonic/sonic/infrasonic waves, measurement devices, instruments, etc., can solve the problems of difficult acquisition of detection thresholds, misjudgment of surrounding ships, and rising noise levels, so as to eliminate ship interference and countermeasures. Play wind speed and rainfall for accurate effects

Active Publication Date: 2019-08-02
THE FIRST INST OF OCEANOGRAPHY SOA
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Problems solved by technology

However, this method also has its disadvantages: this method needs to set a power detection threshold in a certain frequency band in advance, when the noise power exceeds the detection threshold, it is considered that there is a surrounding ship
This detection threshold is difficult to obtain in practice, and it is related to the sensitivity of the hydrophone and the current environmental noise level
Even if an adaptive method is used to track the current environmental noise level, the noise level caused by the increase of wind speed may rise and be misjudged as the surrounding ships

Method used

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Embodiment 1

[0022] Hydrophones used to invert sea surface wind speed and rainfall are generally deployed on platforms such as submersible buoys, buoys, Argos and underwater gliders in a self-contained manner. The impact of platform vibration and noise on the hydrophone should be considered during deployment. In general, the platform should carry out vibration and noise reduction work, including the streamlined design of the main floating body, the use of rubber vibration isolation at the swivel and shackle connections, etc. In addition, the hydrophone and the platform are generally connected by springs or elastic lines to isolate the vibration of the platform.

[0023] When there is a ship passing by around the hydrophone, the noise of the ship will be received by the hydrophone. If it is not effectively identified and eliminated, it will bring large errors to the results of wind speed and rainfall inversion of environmental noise. In addition to the fact that the noise of the ship itsel...

Embodiment 2

[0031] When there is no ship around, the time-domain waveform of the noise signal in the marine environment can be seen in Figure 5 (a). Using the method of the present invention to calculate the modulation significance statistic yields as Figure 5The results shown in (b), where the dotted line is the threshold value of 20, and the solid line is the modulation significance statistic value. It can be seen that the modulation significance statistics do not exceed the threshold during the entire noise signal time, which is in line with expectations. Figure 5 (c) The identification result is given, and the output is 0, indicating that no ship appears. The method of the present invention is further verified.

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Abstract

The invention relates to a robust ship noise identifying method, and belongs to the field of marine signal processing. The method comprises the following steps: firstly an extracted signal is standardized, and then filter and Fourier transform combined processing is used to obtain a modulation spectrum of the signal; secondly, a modulation significance statistic quantity is calculated by dividinga value of a spectrum line with the maximum amplitude in the modulation spectrum by an average amplitude of the modulation spectrum; and finally, the modulation significance statistic quantity is compared with a threshold, if the modulation significance statistic quantity is larger than the threshold, a ship is considered to appear, and if the modulation significance statistic quantity is continuously smaller than the threshold in a period of time, no ship is considered to appear around. According to the method disclosed by the invention, a more stable physical variable, namely, a modulation characteristic of ship noise is utilized; and compared with a mode of using signal power to detect the ship noise, the method is more robust and better in anti-interference performance.

Description

technical field [0001] The invention belongs to the field of marine signal processing, and relates to a method for robust identification of ship noise. Background technique [0002] The wind speed and rainfall on the sea surface can be obtained by inversion of the noise under the sea surface, which provides a new method for the observation of wind speed and rainfall on the sea surface. Noise in the ocean is also affected by surrounding ships and mammals. Before retrieving wind speed and rainfall, it is necessary to identify the noise source first. Mammalian calls are transient and easier to distinguish. When the surrounding ships appear, the overall power level of marine environmental noise will increase, based on which it can be judged whether there are ships around, which is also a commonly used method at present. But this method also has its shortcomings: this method needs to set a power detection threshold in a certain frequency band in advance, and when the noise powe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V1/00G01H17/00
CPCG01H17/00G01V1/00
Inventor 刘宗伟吕连港
Owner THE FIRST INST OF OCEANOGRAPHY SOA
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