Brillouin optical time domain reflectometer and phase demodulation method and device thereof

Abstract

The invention relates to the technical field of phase demodulation, in particular to a Brillouin optical time domain reflectometer and a phase demodulation method and device thereof, and the method comprises the steps: determining the position and range of a disturbance point from an original signal; based on the position and the range of the disturbance point, extracting intensity signals of two different positions closest to the disturbance point; respectively carrying out high-pass filtering processing on the two intensity signals; respectively carrying out normalization processing on the alternating current components of the two processed intensity signals; performing differential cross multiplication and subtraction processing on the two normalized intensity signals respectively; and integrating the phase change after the subtraction processing to obtain a demodulation phase. The problems that an existing phi-BOTDR phase demodulation scheme is complex in demodulation process and low in demodulation efficiency are solved. The method has the advantages that the demodulation process is simple, consumed time is reduced, demodulation efficiency is improved, operation efficiency of the system is improved, and stability and accuracy of demodulation results are improved.

Description

technical field [0001] The invention relates to the technical field of phase demodulation, in particular to a Brillouin optical time domain reflectometer and a phase demodulation method and device thereof. Background technique [0002] Brillouin optical time domain reflectometer (Brillouin optical time domain reflectometer, BOTDR), as a popular distributed optical fiber sensing system, through coherent detection of Brillouin scattered light and phase demodulation (Φ-BOTDR, Phase SensitiveBrillouin Optic time domain reflectometer), realizes the rapid measurement of Brillouin frequency, and can demodulate the relevant information of the stress or vibration of the optical fiber. Due to its high sensitivity and ability of distributed dynamic measurement, Φ-BOTDR has attracted the attention of a large number of researchers and is considered as a promising technology. In particular, the phase demodulation scheme has been a hotspot in the research of Φ-BOTDR. [0003] In recent y...

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Problems solved by technology

[0003] In recent years, in order to demodulate the external vibration information of the optical fiber, various Φ-BOTDR phase extraction schemes have been proposed, such as the digital coherent detection scheme, the phase information can be demodulated with high signal-to-noise ratio accurately, but in the demodulation process, Due to the need for high-speed data acquisition equipment, the amount of data collected is large and time-consuming

[0004] Subsequently, the I / Q demodulation based on homodyne coherent detection can overcome the shortcomings of high sampling rate, but it needs to detect multi-channel data synchronously, and the detection requirements are high; in addition, 3×3 coupler demodulation, I / Q demodulation Modulation and inverse trigonometric function demodulation to extract phase information, due to the addition of components, the structure of Φ-BOTDR is more complicated, which greatly increases the complexity and cost of the system, and the 3×3 coupler obtains three signal data, and the solution The amount of data in the modulation process is large, and the signal data to be processed is more, the demodulation process becomes more and more complicated, takes a long time, and reduces the operating efficiency of the system

[0005] In view of the above-mentioned related technologies, the inventor believes that there is a defect in the existing Φ-BOTDR phase demodulation scheme that the demodulation process is complicated and the demodulation efficiency is low

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