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Method for identifying direct sound in complex multi-path underwater sound environment

An identification method and direct sound technology, applied in the field of direct sound identification, can solve the problem of not fully utilizing multi-path signals and so on.

Inactive Publication Date: 2010-12-01
HARBIN ENG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

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

Method used

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  • Method for identifying direct sound in complex multi-path underwater sound environment
  • Method for identifying direct sound in complex multi-path underwater sound environment
  • Method for identifying direct sound in complex multi-path underwater sound 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, which comprises the steps of: (1) initializing a basic parameter which comprises a large width threshold, a small width threshold, a minimum energy threshold, a concave point compensating threshold and a time delay interval threshold; (2) computing an input signal envelope, wherein a self-adaptive Notch filter is adopted for narrowband filtering and self-adaptive iteration is used for estimating the signal envelope; (3) estimating background noise energy by using a recursive filter; determining an energy threshold by using a self-adaptive threshold and a minimum protective mechanism; (4) detecting energy and adopting a concave point compensating technique; and (5) identifying direct sound, namely judging by using double widths and time intervals. The method can be used for effectively enhancing the identifying rate of a direct sound signal in an environment polluted by reflected sound, effectively removing the interference of sharp pulses in background noise, reducing the detecting thresholds of a processor, and enhancing the universality and the stability.

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...

Claims

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Application Information

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Patent Type & Authority Applications(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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