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Line spectrum signal detection method

A detection method and signal technology, applied in measuring devices, spectrum analysis, measuring electrical variables, etc., can solve problems such as difficult to determine the signal detection threshold, and achieve the effect of small amount of calculation

Pending Publication Date: 2022-02-11
THE PLA NAVY SUBMARINE INST
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Problems solved by technology

However, since the strength of the ship's low-frequency physical field signal is greatly affected by the target and distance, it is difficult to determine the detection threshold of the signal when using the energy detection method to detect low-frequency signals

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Embodiment Construction

[0024] Such as figure 1 Shown, a kind of detection method of line spectrum signal is characterized in that: comprise the following steps,

[0025] S1- For a time window t with a fixed duration such as about 20s 0 The low-frequency signal x(t) obtained in the acquisition is calculated by FFT, and the spectrum X of the signal is obtained fft and remove the DC component to get X FFT for

[0026] x FFT =[X 0 , X 1 ,L,X N ] Formula 1)

[0027] In formula 1), N is the number of frequency points, X i The corresponding frequency is F i ;

[0028] S2-to-X FFT Energy normalization is carried out to improve the dynamic observation range. When the ship detects nodes from far to near, the energy difference can reach tens to hundreds of times, and the energy changes little in the observation time of about 20s. It is obtained:

[0029]

[0030] S3 - Calculate X FFT norm The detection threshold value is a combination of adaptive floating threshold and fixed threshold, and its...

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Abstract

The invention relates to a line spectrum signal detection method. The detection method comprises the following steps that: S1, FFT calculation is performed on a low-frequency signal x (t) acquired in a fixed-time-length time window t0 to obtain a frequency spectrum Xfft of the signal, and a direct-current component is removed, so that XFFT can be obtained; S2, energy normalization is performed on the XFFT to improve a dynamic observation range; S3, a detection threshold value of XFFTnorm is calculated, wherein the detection threshold value is a combination of a self-adaptive floating threshold and a fixed threshold; S4, the XFFTnorm is compared with an Xthreshold, and a suspected line spectrum frequency point is judged; and S5, time integration is carried out on T = [T0, T1, L, TN], if the maximum frequency Q of the suspected line spectrum frequency point in a certain time window M is greater than a certain set value R, it is judged that a suspected target appears, and if the suspected target appears in a plurality of continuous seconds t1, it is judged that a target signal appears. According to the method of the invention, the characteristic change of a self-adaptive filter can be realized, and the detection threshold of the signal can be accurately determined.

Description

technical field [0001] The invention relates to a detection method of a line spectrum signal. Background technique [0002] Ship electric field has become a significant ship characteristic signal, which can be used for ship detection, tracking, positioning and strike. Russia, the United States, the United Kingdom, Canada and other countries have made considerable achievements in the research of ship electric field, while domestic research is far behind. Grasping the true characteristics of electric field distribution is the basis of electric field research, which puts forward an urgent need for electric field measurement, and electric field has obvious spectral characteristics. [0003] The process of filtering out noise and interference from continuous or discrete input data and extracting useful information is called filtering, and the corresponding device that realizes this process is called a filter. A filter can be seen as a system whose purpose is to extract a useful...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R29/14G01R23/165
CPCG01R29/14G01R23/165
Inventor 张海鹏张嘉恩
Owner THE PLA NAVY SUBMARINE INST
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