Distributed optical fiber vibration sensing system and phase carrier demodulation method thereof

Abstract

The invention discloses a distributed optical fiber vibration sensing system based on Rayleigh back scattering and Mach-Zehnder interference. The system comprises a phase sensitive optical time domain reflectometer, a one-way Mach-Zehnder optical fiber interferometer, a photoelectric detector and a signal processing unit which are connected in sequence, and also comprises a signal source used for generating a periodic pulse signal and a periodic high-frequency modulation signal; the signal processing unit collects sensing electric signals transmitted back by the photoelectric detector and then analyzes and demodulates the received signals so as to demodulate amplitude-frequency information of vibration signals applied to the sensing optical fiber. The invention also discloses a phase carrier demodulation method, which can effectively realize linear demodulation of a vibration signal applied to the sensing optical fiber by using a phase carrier demodulation technology which is not influenced by interference light intensity and modulation depth.

Description

technical field [0001] The invention belongs to the technical field of sensing and detection, in particular to a distributed optical fiber vibration sensing system based on Rayleigh scattering and Mach-Zehnder interference and a phase carrier demodulation method thereof. Background technique [0002] Distributed optical fiber vibration sensing technology can realize continuous multi-point vibration sensing detection along the line with a single optical fiber link, and its positioning accuracy can be adjusted through hardware parameters such as optical path. Compared with traditional electromagnetic vibration sensing technology, distributed optical fiber vibration sensing technology has many advantages such as simple structure, high sensitivity, and anti-electromagnetic interference. At present, this technology has been successfully applied in perimeter security detection, pipeline security detection, submarine cable fault detection, power line fault detection and many other ...

AI Technical Summary

Problems solved by technology

The introduction of these structures increases the complexity of the distributed optical fiber vibration sensing system and reduces the real-time performance of system demodulation to a certain extent

Although the interferometric optical fiber vibration sensing system has a linear relationship between the interference light intensity and the externally applied vibration signal, it is limited by the shortcomings of the inability to use a single interferometer to locate the structural vibration signal and the small dynamic range of interference signal demodulation. its application in practice

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