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Optical fiber sensing device and demodulation method for simultaneous measurement of disturbance waveform and position

A fiber optic sensing and waveform technology, which is applied in measuring devices, using optical devices to transmit sensing components, converting sensor outputs, etc., can solve the problem that the dynamic range of the PGC demodulation algorithm is limited, and the positioning of the zero frequency point method depends on the frequency of the disturbance signal etc. to achieve the effect of reducing the minimum sampling frequency, eliminating the dependence on the frequency of the disturbance signal, and being easy to implement

Active Publication Date: 2021-03-30
TIANJIN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to solve the problem that the dynamic range of the PGC demodulation algorithm is limited and the positioning of the zero-frequency point method based on spectral transformation depends on the frequency of the disturbance signal, and provide a fiber optic sensing device and demodulation method for simultaneous measurement of the disturbance waveform and position, The detection of the external disturbance waveform and the determination of the external disturbance position are realized by the dual-wavelength Sagnac interferometer

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  • Optical fiber sensing device and demodulation method for simultaneous measurement of disturbance waveform and position
  • Optical fiber sensing device and demodulation method for simultaneous measurement of disturbance waveform and position
  • Optical fiber sensing device and demodulation method for simultaneous measurement of disturbance waveform and position

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Embodiment 1

[0030] as attached figure 1 As shown, the optical fiber sensing device for simultaneous measurement of disturbance waveform and position of the present invention includes a light source, a dual-wavelength multiplexed Sagnac interferometer, four photodetectors, and a demodulation circuit comprising four preprocessing circuits and two-way digital processing parts The light source is connected with the input end of the dual-wavelength multiplexing Sagnac interferometer, and each branch of the four output ends of the dual-wavelength multiplexing Sagnac interferometer is connected with a photodetector (PD), and the first output port is connected to the first photoelectric The detector is connected, the second output end is connected with the second photodetector, the third output end is connected with the third photodetector, the fourth output end is connected with the fourth photodetector, and the output voltage of each photodetector The signals pass through the corresponding ones...

Embodiment 2

[0035] The structure of the optical fiber sensing device for simultaneous measurement of disturbance waveform and position is the same as that of Embodiment 1.

[0036] In this embodiment, the light source is a broadband light source, the distance between the e port of the 3×3 coupler and the h port of the 1×2 coupler is 8m, the d port of the 3×3 coupler and the g port of the 1×2 coupler The difference between the distance between the ports and the distance between the e port of the 3×3 coupler and the h port of the 1×2 coupler is 5km, the length of the sensing fiber is 50km, and the wavelength of the narrowband filter is λ 1 and lambda 2 , assuming that the vibration point to be measured is placed 10km away from the 1×2 coupler, the sampling frequency of the signal in the demodulation circuit is selected as 500kHz, the amplitude of the signal to be measured is 1rad, and the frequency is 150Hz and 100Hz chirp signal. The signal detected by the photodetector is demodulated by ...

Embodiment 3

[0038] The structure of the optical fiber sensing device for simultaneous measurement of disturbance waveform and position is the same as that of Embodiment 1.

[0039] In this embodiment, the light source is a broadband light source, the distance between the e port of the 3×3 coupler and the h port of the 1×2 coupler is 8m, the d port of the 3×3 coupler and the g port of the 1×2 coupler The difference between the distance between the ports and the distance between the e port of the 3×3 coupler and the h port of the 1×2 coupler is 5km, the length of the sensing fiber is 50km, and the wavelength of the narrowband filter is λ 1 and lambda 2 , assuming that the vibration point to be measured is placed at a distance of 15km from the 1×2 coupler, the sampling frequency of the signal in the demodulation circuit is selected as 500kHz, and the signal to be tested is selected as a sinusoidal signal with an amplitude of 1rad and a frequency of 100Hz. The signal detected by the photodet...

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Abstract

The invention provides an optical fiber sensing device for simultaneous measurement of disturbance waveform and position and a demodulation method thereof. The device comprises a dual-wavelength Sagnac interferometer, a photoelectric detector and a signal demodulation part. The dual-wavelength Sagnac interferometer is established to perceive the disturbance signal. In the signal demodulation part,the unsymmetrical division algorithm based on the 3 x 3 coupler is applied to demodulate the disturbance signal waveform correctly, and the disturbance position is obtained by the phase ratio localization method. The device has the advantages that: in the optical path part, the dual-wavelength Sagnac interferometer multiplexes the same sensing optical fiber so that the signal-to-noise ratio of the system can be improved; and in the demodulation algorithm part, the asymmetric division algorithm based on the 3 x 3 coupler has low sampling frequency without carrier signal and resists interference of light intensity without harmonic distortion, and the phase ratio localization method can locate the disturbance signal of any frequency.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to an optical fiber sensing device and a demodulation method for simultaneously measuring disturbance waveforms and positions. Background technique [0002] Interferometric fiber optic sensors have been applied to various fields, such as perimeter security, oil spills, hydrophones, etc., because of their advantages such as high sensitivity, anti-electromagnetic interference, large dynamic range, diverse structures, and easy reuse. Typical interferometry techniques include Sagnac interferometry, Michelson interferometry, and M-Z interferometry. Among them, the Sagnac interferometer and Michelson interferometry both use the zero-frequency point method based on spectral transformation to locate, thus limiting the frequency of the detectable disturbance signal, while the light in the M-Z interferometer propagates through two optical fibers respectively, and the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01D5/353
CPCG01D5/35322G01D5/3538G01D5/35387
Inventor 张爱玲李丹
Owner TIANJIN UNIVERSITY OF TECHNOLOGY