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Direct sound identification method in complex multi-path underwater acoustic environment

A technology of direct sound and environment, applied in the field of direct sound identification, which can solve the problem of underutilization of multi-path signals.

Inactive Publication Date: 2012-02-01
HARBIN ENG UNIV
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Problems solved by technology

These technologies all start from the perspective of suppressing multi-path, but do not make full use of the characteristics of multi-path signals

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  • Direct sound identification method in complex multi-path underwater acoustic environment
  • Direct sound identification method in complex multi-path underwater acoustic environment
  • Direct sound identification method in complex multi-path underwater acoustic environment

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Embodiment Construction

[0029] The present invention is described in more detail below in conjunction with accompanying drawing example:

[0030] The basic parameters of the transmitted signal: CW pulse, pulse width 10ms, center frequency 5kHz; the transmitted signal reaches the receiving point through the underwater acoustic channel, and the channel sound velocity distribution characteristics are as follows: figure 1 shown. The position of the transmitting point is (0, 0, 5) m, the depth of the receiving point is 30 m, and the horizontal distance between the two varies from 0 m to 2 km. The characteristics of multi-channel channels at different distances and the delay difference between direct sound and reflected sound are as follows: figure 2 , image 3 shown. Figure 4 The time-domain waveform (normalized amplitude) of the direct sound interfered by the reflected sound in a typical multi-channel channel is given.

[0031] For above-mentioned conditions, provide the expert system processing st...

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Abstract

The invention provides a method for identifying direct sound in a complex multi-path underwater sound environment. (1) Initialize the basic parameters, which include a large width threshold, a small width threshold, a minimum energy threshold, a sink point compensation threshold, and a time delay interval threshold; (2) calculate the input signal envelope, using an adaptive Notch filter to do Narrowband filtering, and use its adaptive iterative weight to estimate the signal envelope; (3) Estimate the energy of the background noise and determine the energy threshold. The noise energy is estimated using a first-order recursive filter, and the energy threshold is selected using an adaptive threshold and a minimum protection mechanism; ( 4) Energy detection, and the use of sag point compensation technology; (5) Direct sound recognition, that is, double width judgment and time interval judgment are used. The invention can effectively improve the recognition rate of the direct sound signal in the environment polluted by the reflected sound. At the same time, it can effectively remove the spike interference in the background noise, reduce the detection threshold of the processor, and improve the universality and robustness of the method.

Description

technical field [0001] The invention belongs to the field of underwater acoustic engineering, signal and information processing, and in particular relates to a direct sound identification method in a complex underwater acoustic multi-channel environment. Background technique [0002] As the medium for underwater acoustic signal transmission, the ocean is equivalent to a filter for transforming the transmitted signal. Due to the existence of the sea-bottom interface and the inhomogeneity of the seawater medium, the underwater acoustic channel presents multi-path characteristics, and the acoustic signals sent from the sound source arrive at the receiving point along various paths, and they interfere with each other and superimpose, resulting in complex spatial interference pattern and filter properties. Interferenced by one or more reflections from the sea surface and the bottom of the sea, as well as the influence of relative motion, the amplitude, frequency, and phase of th...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01H17/00
Inventor 梁国龙付进王燕张光普林旺生王逸林嵇建飞范展
Owner HARBIN ENG UNIV
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