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Flexibly-configured low cost fiber disturbance event end point detection method and flexibly-configured low cost fiber disturbance event end point detector

An endpoint detection, low-cost technology, applied in the exploration of optical devices, etc., can solve the problems of high computing cost and high computing complexity, and achieve the effect of reducing computing cost, low computing complexity, and high timeliness

Active Publication Date: 2016-05-04
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this algorithm needs to set a relatively long frequency vector (N=256), which will bring high computational complexity, and will generate large computational costs in actual engineering

Method used

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  • Flexibly-configured low cost fiber disturbance event end point detection method and flexibly-configured low cost fiber disturbance event end point detector
  • Flexibly-configured low cost fiber disturbance event end point detection method and flexibly-configured low cost fiber disturbance event end point detector
  • Flexibly-configured low cost fiber disturbance event end point detection method and flexibly-configured low cost fiber disturbance event end point detector

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] see figure 2 , a flexible configurable low-cost optical fiber disturbance event endpoint detection method includes the following steps:

[0053] 101: Extract a section of undisturbed and disturbed downsampled samples (downsampling factor D) respectively, perform fast Fourier transform (FFT) analysis on the two sections of samples, and obtain frequency band distributions respectively;

[0054] Choose an appropriate cutoff frequency f c , to convert the cutoff frequency to a digital angular frequency ω c =2πf c / f s (f s is the input signal sampling rate), set the filter length L, make N=(L+1) / 2 and the frequency unit Δω=2π / N, so as to determine the integer and decimals m is the stopband width of the high-pass filter; λ is the frequency translation amount; N is the length of the filter frequency vector.

[0055] 102: Obtain the frequency shift filter coefficient g through m, λ and N 0 (n):

[0056] g 0 ( ...

Embodiment 2

[0081] The scheme in embodiment 1 is described in detail below in conjunction with specific calculation formulas, accompanying drawings, and examples, see the following description for details:

[0082] The purpose of the embodiments of the present invention is to obtain the starting position of the signal disturbance quickly and accurately under different environments, and at the same time, for practical engineering considerations, the calculation cost of the endpoint detector should be as small as possible (that is, the multiplication cost of the filter processor and adder resources are sufficiently small). from figure 2 It can be seen that the configurable high-pass filter with low computational complexity is the key to the entire endpoint detection process, and whether a filter that meets the requirements can be configured directly determines the performance of the endpoint detector.

[0083] The main flow of the filter design adopted in the embodiment of the present inv...

example 1

[0122] Example 1: Set the length of the high-pass filter N = 32, the desired 3dB cut-off frequency ω c = 4.5Δω, then the relevant parameters can be obtained by formula (12)-(14): frequency shift filter passband cut-off frequency ω p = ω c -0.707Δω=3.8Δω, The ω(n) window selects the Hamming convolution single window. Substituting these parameters into formula (9) can get the filter coefficient analytical formula g 0 (n), and then perform Fourier transform to obtain the transmission curve of the frequency shift filter, as shown in the figure below.

[0123] Since the 3dB cut-off frequency of the high-pass filter is set, ω c The magnitude at the corresponding low-pass filter should be Figure 5 , the passband and stopband cut-off frequencies are marked as circles, ω c Denoted by dashed lines, it can be seen that all three parameters fall exactly where expected.

[0124] 2. Compensation filter design

[0125] according to Figure 5 It can be seen that although the fi...

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Abstract

The invention discloses a flexibly-configured low cost fiber disturbance event end point detection method and a flexibly-configured low cost fiber disturbance event end point detector. The method comprises steps that a frequency shift filter coefficient is acquired through stop band width, frequency translation amount and filter frequency vector length, Fourier transform for the frequency shift filter coefficient is carried out, a compensation filter coefficient is further acquired through a Kaiser window and a rectangular window; a frequency shift compensation low pass filter coefficient is acquired through the frequency shift filter coefficient and the compensation filter coefficient; the frequency shift compensation low pass filter coefficient is processed, and a high pass filter is acquired; a signal after downsampling is inputted to the high pass filter, and a filtering output sequence is acquired; the first position of the filtering output sequence having an energy value greater than the energy threshold is searched, and the position is the disturbance start point. The detector comprises an analog-digital converter, an FFT analyzer and a DSP device. Through the method and the device, parameter adjustment can be realized, various environment background demands can be satisfied, and quite high timeliness and relatively low cost are realized.

Description

technical field [0001] The invention relates to the technical field of digital signal processing, in particular to a method for finding a vibration starting point for disturbance signals caused by various intrusion actions in an all-fiber perimeter security system. Background technique [0002] With the development of optical fiber communication technology, optical fiber sensing technology has rapidly become an emerging technology. As an important application of this technology, the fiber optic perimeter security system [1] Due to its advantages of high sensitivity, safety and reliability, anti-electromagnetic interference and large amount of transmitted information, it has also received more and more attention. The optical fiber perimeter security system can continuously and effectively monitor the vibration generated by the intrusion behavior along the optical fiber. When an external intrusion event occurs [2][3] (climbing the fence, stealing the fence and knocking on th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01V8/10
CPCG01V8/10
Inventor 黄翔东王越冬刘铁根刘琨
Owner TIANJIN UNIV
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