Phi-OTDR quantitative measurement method based on integral least square fitting

An overall least squares, -OTDR technology, applied in the direction of electromagnetic wave transmission system, electromagnetic receiver, electrical components, etc., can solve the problems such as phase can not be demodulated, difficult, etc., to reduce laser frequency drift, reduce error, highly repeatable sexual effect

Active Publication Date: 2019-07-23
NANJING UNIV
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Problems solved by technology

To make matters worse, since the light source used by the phase optical time domain reflectometer is a highly coherent light source, there will be fading zeros in the detection curve generated by the Rayleigh backsca

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  • Phi-OTDR quantitative measurement method based on integral least square fitting
  • Phi-OTDR quantitative measurement method based on integral least square fitting
  • Phi-OTDR quantitative measurement method based on integral least square fitting

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[0048] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:

[0049] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in commonly used dictionaries should be understood to have a meaning consistent with the meaning in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless defined as herein explain.

[0050] figure 2 is a schematic diagram of a phase optical time domain reflectometer, which uses coherent detection. In this embodiment, the laser LD adopts a high-coherence light source, the line width is less than 100 Hz, the wavelength is set at 1550 nm, and the power is set at 40 mW. After passing t...

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Abstract

The invention provides a Phi-OTDR quantitative measurement method based on integral least square fitting, and relates to the technical field of optical fiber sensing. In a phase optical time domain reflectometer based on a digital coherent detection mode, optical phases for measuring dynamic events on the optical fiber are continuously accumulated in the length direction of the optical fiber, dueto the nonuniformity of refractive index distribution of the optical fiber, the accumulated phases have the characteristic of random distribution in the length direction of the optical fiber, and thefrequency drift of laser also affects a measurement result. In order to obtain accurate quantitative demodulation results, through a series of data acquisition and processing processes such as data acquisition, coordinate regulation, position judgment, original phase resolution, new origin setting, phase subtraction and mean value removal, a relatively smooth phase change value is obtained in thelength direction of the optical fiber, and in order to further achieve accurate solution, a solution result is obtained after the processes of data fitting and applicable judgment. According to the method, the influence of laser frequency drift is reduced as much as possible, and meanwhile, the influence of noise such as polarization fading is reduced, so that the measurement result has high reliability and accuracy.

Description

technical field [0001] The invention relates to the technical field of optical fiber sensing, in particular to a method for quantitative measurement of Φ-OTDR based on overall least squares fitting. Background technique [0002] Distributed optical fiber sensing technology is an important branch of optical fiber sensing technology. It uses the signal carried by the backscattered light in the optical fiber to locate, identify, and measure events along the optical fiber. In the backscattered light, according to the different physical mechanism and parameter characteristics, it can be divided into Rayleigh scattered light, Brillouin scattered light and Raman scattered light. Among them, the Rayleigh scattered light is based on the elastic effect, and the light intensity is relatively large among the three kinds of backscattered light, and relatively speaking, it is the easiest to detect. [0003] Based on Rayleigh backscattered light, people invented OTDR (optical time domain ...

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Application Information

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IPC IPC(8): H04B10/071H04B10/61
CPCH04B10/071H04B10/6165
Inventor 张旭苹钟镇王峰张益昕
Owner NANJING UNIV
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