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Instantaneous Frequency Demodulation Method of Underwater Acoustic Signal Based on Wavelet Ridge

A technology of underwater acoustic signal and instantaneous frequency, applied in the direction of measuring ultrasonic/sonic wave/infrasonic wave, using wave/particle radiation, measuring devices, etc., can solve the problem of gross error, cannot determine the instantaneous frequency of underwater acoustic signal, and frequency detection accuracy depends on and other issues, to achieve good anti-interference effect

Active Publication Date: 2017-03-01
HARBIN INST OF TECH
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to propose a method for demodulating the instantaneous frequency of underwater acoustic signals based on wavelet ridges, to solve the problem that the existing conventional signal demodulation method is a spectrum analysis method, and the spectrum analysis method cannot determine the instantaneous frequency of the underwater acoustic signal. Frequency; when calculating the frequency of an underwater acoustic signal, the detection accuracy of the frequency depends on the setting of the spectrum threshold, and the problem of gross error often occurs

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  • Instantaneous Frequency Demodulation Method of Underwater Acoustic Signal Based on Wavelet Ridge
  • Instantaneous Frequency Demodulation Method of Underwater Acoustic Signal Based on Wavelet Ridge
  • Instantaneous Frequency Demodulation Method of Underwater Acoustic Signal Based on Wavelet Ridge

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specific Embodiment approach 1

[0027] Specific embodiment one: a kind of instantaneous frequency demodulation method of underwater acoustic signal based on wavelet ridge described in this embodiment comprises the following steps:

[0028] Step 1, using the Michelson laser interferometry system to detect the water surface;

[0029] Step 2, collecting the laser interference signal, the collection process is: the interference signal is received by the photodetector, and converted into an electrical signal, and the electrical signal is collected by the data acquisition card and then transmitted to the host computer;

[0030] Step 3, performing frequency spectrum analysis on the collected interference signal to determine the frequency distribution range of the underwater acoustic signal;

[0031] Step 4, determining the observation scale of the wavelet transform;

[0032] After step three, the frequency range of the signal spectrum can be known, and the observation scale of the wavelet transform can be determin...

specific Embodiment approach 2

[0066] Embodiment 2: This embodiment differs from Embodiment 1 in that the frequency spectrum analysis described in step 3 refers to the use of a Fast Fourier Transform algorithm, ie, FFT algorithm, for the collected interference signal. Other steps are the same as in the first embodiment.

specific Embodiment approach 3

[0067] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is: the specific process of the wavelet transformation described in step five is:

[0068] Choose Morlet wavelet as the mother wavelet, and its approximate mathematical expression is

[0069]

[0070] In the formula, ω 0 is the central angular frequency of the mother wavelet, σ is the Gaussian function parameter, j is the imaginary number symbol, t is the time, and the corresponding Fourier transform is:

[0071]

[0072] ω is the angular frequency, then the calculation formula for the wavelet transform coefficient of the interference signal is as follows:

[0073]

[0074] In the formula, is a function family with Morlet wavelet as the mother wavelet, a is the scale factor, and b is the translation factor, that is is a function family obtained by shifting and stretching the wavelet mother function, f(t) is the collected interference signal, W f (a, b) are...

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Abstract

The invention belongs to the technical field of underwater sound signal detection, and relates to underwater sound signal instantaneous frequency demodulation, in particular to an underwater sound signal instantaneous frequency demodulation method based on wavelet ridges. The method solves the problems that an existing conventional signal demodulation method is a spectral analysis method which cannot determine the instantaneous frequency of underwater sound signals, frequency detecting precision depends on a set frequency spectrum threshold value when the frequency of the underwater sound signals is calculated, and gross errors occur frequently. According to the technical scheme, signal wavelets are converted to obtain a wavelet conversion coefficient, the distribution positions of wavelet ridge points at all moments are obtained through a local mode maximum value method, center sizes of the wavelet ridges at all moments are calculated according to the distribution positions of the wavelet ridge points, and instantaneous frequencies of all moments are resolved according to the center sizes of the wavelet ridges. The underwater sound signal instantaneous frequency demodulation method based on the wavelet ridges is applicable to the fields of detection of sound generation frequency of an underwater sound generation target, detection of liquid surface sound wave frequency and measurement of vibration frequency of micro amplitude machines.

Description

technical field [0001] The invention relates to the demodulation of the instantaneous frequency of underwater acoustic signals, in particular to a method for demodulating the instantaneous frequency of underwater acoustic signals based on wavelet ridges, and belongs to the technical field of underwater acoustic signal detection. Background technique [0002] The underwater sound source radiates sound waves outward, which can form water surface acoustic waves propagating laterally on the water surface. The vibration frequency of the water surface acoustic wave is consistent with the sound frequency of the underwater sound source, so the water surface acoustic wave carries the relevant information of the underwater acoustic signal . Therefore, due to the needs of underwater target detection, more and more attention is paid to the detection and utilization of water surface acoustic waves. The laser interferometry method can obtain the frequency information of the underwater ac...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01H9/00
Inventor 张晓琳张烈山唐文彦邹斌王军
Owner HARBIN INST OF TECH