Optical cable wiring structure based on POTDR system for measuring disturbance

A wiring structure and optical cable technology, applied in the field of polarized light time domain reflection detection, can solve the problem of no optical cable birefringence sensitivity optical cable wiring method, etc., and achieve the effects of improving sensitivity, large laying area, and improving accuracy

Active Publication Date: 2019-09-13
NANJING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The change of the polarization state of the light wave in the optical cable is mainly caused by the change of the birefringence, and so far, the optical cable wiring meth

Method used

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  • Optical cable wiring structure based on POTDR system for measuring disturbance
  • Optical cable wiring structure based on POTDR system for measuring disturbance
  • Optical cable wiring structure based on POTDR system for measuring disturbance

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0043] Example one

[0044] figure 1 (a) shows the S-shaped wiring structure. Such as figure 1 As shown in (a), the optical cable is arranged on a bottom line in an "S" shape. According to the analysis of the working principle, if the phase difference δ caused by bending birefringence is to be greater than or equal to 0.02π, the downward bending radius caused by pedaling is required to be less than or equal to 68mm. However, due to the limitation of the height of the base, the distance between the contact end of the optical cable and the ground and the base at this time is l, and the length of the optical cable affected by bending is about The actual phase difference change is Less than 0.02π. In order to achieve the required phase difference, the downward bending radius needs to be further reduced. According to calculations, the required downward bending radius is R=30mm, and the length of the optical cable affected at this time is 8.71πmm. At this time, the force required ...

Example Embodiment

[0046] Example two

[0047] figure 1 (b) shows the ring wiring structure. Such as figure 1 As shown in (b), the optical cable is laid on the base line in a ring shape. In this wiring structure, induced birefringence is still mainly caused by bending. The layout parameters are approximately the same as in the S"-shaped wiring scheme. The difference is that due to the circular layout, under the same external event, the length of the affected optical cable becomes twice that in the first embodiment. Because of more The optical cable disperses the pedaling force, so the pressure on the optical cable per unit length will be less than the "S"-shaped wiring scheme. However, because the length of the affected optical cable is doubled, the overall sensitivity is better than that of the first embodiment, but for the same The length of the optical cable required for the monitoring area will be doubled.

[0048] In this example, we bent and fixed the optical cable on top of the bottom line ...

Example Embodiment

[0049] Example three

[0050] figure 1 (c) shows the overlapping ring wiring structure. Such as figure 1 As shown in (c), in the overlapping ring wiring structure, the overlapping ring layout is similar to the ring layout, but based on it, the back arc line is placed on the previous arc line, so there are more bending points. The degree of bending is higher, which can significantly improve the sensitivity of the system in the second wiring scheme.

[0051] In this example, we bent and fixed the optical cable on top of the bottom line according to the circular wiring method, and then placed the optical cable on figure 2 Between the coupler and the analyzer, the optical fiber signals are collected in different places of the optical cable, taking the walking of a normal person as an example. Then the collected signal is processed by MATLAB software, where Figure 5 It is the result of the polarization signal differential curve obtained by applying pressure on two different position...

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Abstract

The invention discloses an optical cable wiring structure based on a POTDR system for measuring disturbance. The optical cable wiring structure comprises a pulse laser, a polarizer, a coupler, an analyzer, a detector, a signal collection module, a signal processing module, an optical cable and a bottom line; the optical cable is horizontally bent and arranged on the bottom line, and the bottom line is used for generating a bottom height for the optical cable, so that the optical cable is bent in a vertical direction when subjected to a vertical pressure. The optical cable cable is arranged inan ''S'' shape on the bottom line; or the optical cable is coiled into a plurality of circles to be arranged on the bottom line, the circle centers of the circles are distributed on the bottom line, and the adjacent circle centers have the same distance, and the circles have the same size and are not overlapped with each other; or the circles have the same size and are partially overlapped with each other. Compared with straight wiring, the optical cable wiring structure disclosed by the invention not only has a larger effective pavement area, but also can bend the optical cable to a greater extent under the same stress variation, thereby greatly improving the sensitivity of the POTDR system and improving the accuracy of intrusion detection.

Description

technical field [0001] The invention relates to the field of polarized light time-domain reflection detection, in particular to an optical cable wiring structure for measuring disturbance based on a POTDR system. Background technique [0002] The Polarization Optical Time-Domain Reflectometer (POTDR) can realize the distributed measurement of the disturbance to the optical fiber by detecting the change of the polarization state of the light wave in the optical fiber, and has great application potential in the field of perimeter security. However, most of the current sensing research on POTDR is to directly load the vibration signal on the bare optical fiber. However, the bare optical fiber is easy to break and is difficult to be directly used in actual measurement tasks outdoors or indoors. In practical applications, it is often necessary to use optical cables with good protection for optical fibers as the sensing medium. In the POTDR experiment carried out with optical ca...

Claims

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Application Information

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IPC IPC(8): G01D5/353G01H9/00
CPCG01D5/35354G01D5/35374G01H9/004
Inventor 窦蓉蓉张子敬张伦强张元成庄建军
Owner NANJING UNIV
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